diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index 18f179807563..c30c1957c7e6 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html @@ -155,8 +155,7 @@ keeping lock contention under control at all tree levels regardless of the level of loading on the system.

RCU updaters wait for normal grace periods by registering -RCU callbacks, either directly via call_rcu() and -friends (namely call_rcu_bh() and call_rcu_sched()), +RCU callbacks, either directly via call_rcu() or indirectly via synchronize_rcu() and friends. RCU callbacks are represented by rcu_head structures, which are queued on rcu_data structures while they are diff --git a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html index 19e7a5fb6b73..57300db4b5ff 100644 --- a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html +++ b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html @@ -56,6 +56,7 @@ sections. RCU-preempt Expedited Grace Periods

+CONFIG_PREEMPT=y kernels implement RCU-preempt. The overall flow of the handling of a given CPU by an RCU-preempt expedited grace period is shown in the following diagram: @@ -139,6 +140,7 @@ or offline, among other things. RCU-sched Expedited Grace Periods

+CONFIG_PREEMPT=n kernels implement RCU-sched. The overall flow of the handling of a given CPU by an RCU-sched expedited grace period is shown in the following diagram: @@ -146,7 +148,7 @@ expedited grace period is shown in the following diagram:

As with RCU-preempt, RCU-sched's -synchronize_sched_expedited() ignores offline and +synchronize_rcu_expedited() ignores offline and idle CPUs, again because they are in remotely detectable quiescent states. However, because the diff --git a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html index 8d21af02b1f0..c64f8d26609f 100644 --- a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html +++ b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html @@ -34,12 +34,11 @@ Similarly, any code that happens before the beginning of a given RCU grace period is guaranteed to see the effects of all accesses following the end of that grace period that are within RCU read-side critical sections. -

This guarantee is particularly pervasive for synchronize_sched(), -for which RCU-sched read-side critical sections include any region +

Note well that RCU-sched read-side critical sections include any region of code for which preemption is disabled. Given that each individual machine instruction can be thought of as an extremely small region of preemption-disabled code, one can think of -synchronize_sched() as smp_mb() on steroids. +synchronize_rcu() as smp_mb() on steroids.

RCU updaters use this guarantee by splitting their updates into two phases, one of which is executed before the grace period and diff --git a/Documentation/RCU/NMI-RCU.txt b/Documentation/RCU/NMI-RCU.txt index 687777f83b23..881353fd5bff 100644 --- a/Documentation/RCU/NMI-RCU.txt +++ b/Documentation/RCU/NMI-RCU.txt @@ -81,18 +81,19 @@ currently executing on some other CPU. We therefore cannot free up any data structures used by the old NMI handler until execution of it completes on all other CPUs. -One way to accomplish this is via synchronize_sched(), perhaps as +One way to accomplish this is via synchronize_rcu(), perhaps as follows: unset_nmi_callback(); - synchronize_sched(); + synchronize_rcu(); kfree(my_nmi_data); -This works because synchronize_sched() blocks until all CPUs complete -any preemption-disabled segments of code that they were executing. -Since NMI handlers disable preemption, synchronize_sched() is guaranteed +This works because (as of v4.20) synchronize_rcu() blocks until all +CPUs complete any preemption-disabled segments of code that they were +executing. +Since NMI handlers disable preemption, synchronize_rcu() is guaranteed not to return until all ongoing NMI handlers exit. It is therefore safe -to free up the handler's data as soon as synchronize_sched() returns. +to free up the handler's data as soon as synchronize_rcu() returns. Important note: for this to work, the architecture in question must invoke nmi_enter() and nmi_exit() on NMI entry and exit, respectively. diff --git a/Documentation/RCU/UP.txt b/Documentation/RCU/UP.txt index 90ec5341ee98..53bde717017b 100644 --- a/Documentation/RCU/UP.txt +++ b/Documentation/RCU/UP.txt @@ -86,10 +86,8 @@ even on a UP system. So do not do it! Even on a UP system, the RCU infrastructure -must- respect grace periods, and -must- invoke callbacks from a known environment in which no locks are held. -It -is- safe for synchronize_sched() and synchronize_rcu_bh() to return -immediately on an UP system. It is also safe for synchronize_rcu() -to return immediately on UP systems, except when running preemptable -RCU. +Note that it -is- safe for synchronize_rcu() to return immediately on +UP systems, including !PREEMPT SMP builds running on UP systems. Quick Quiz #3: Why can't synchronize_rcu() return immediately on UP systems running preemptable RCU? diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index 6f469864d9f5..e98ff261a438 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -182,16 +182,13 @@ over a rather long period of time, but improvements are always welcome! when publicizing a pointer to a structure that can be traversed by an RCU read-side critical section. -5. If call_rcu(), or a related primitive such as call_rcu_bh(), - call_rcu_sched(), or call_srcu() is used, the callback function - will be called from softirq context. In particular, it cannot - block. +5. If call_rcu() or call_srcu() is used, the callback function will + be called from softirq context. In particular, it cannot block. -6. Since synchronize_rcu() can block, it cannot be called from - any sort of irq context. The same rule applies for - synchronize_rcu_bh(), synchronize_sched(), synchronize_srcu(), - synchronize_rcu_expedited(), synchronize_rcu_bh_expedited(), - synchronize_sched_expedite(), and synchronize_srcu_expedited(). +6. Since synchronize_rcu() can block, it cannot be called + from any sort of irq context. The same rule applies + for synchronize_srcu(), synchronize_rcu_expedited(), and + synchronize_srcu_expedited(). The expedited forms of these primitives have the same semantics as the non-expedited forms, but expediting is both expensive and @@ -212,20 +209,20 @@ over a rather long period of time, but improvements are always welcome! of the system, especially to real-time workloads running on the rest of the system. -7. If the updater uses call_rcu() or synchronize_rcu(), then the - corresponding readers must use rcu_read_lock() and - rcu_read_unlock(). If the updater uses call_rcu_bh() or - synchronize_rcu_bh(), then the corresponding readers must - use rcu_read_lock_bh() and rcu_read_unlock_bh(). If the - updater uses call_rcu_sched() or synchronize_sched(), then - the corresponding readers must disable preemption, possibly - by calling rcu_read_lock_sched() and rcu_read_unlock_sched(). - If the updater uses synchronize_srcu() or call_srcu(), then - the corresponding readers must use srcu_read_lock() and +7. As of v4.20, a given kernel implements only one RCU flavor, + which is RCU-sched for PREEMPT=n and RCU-preempt for PREEMPT=y. + If the updater uses call_rcu() or synchronize_rcu(), + then the corresponding readers my use rcu_read_lock() and + rcu_read_unlock(), rcu_read_lock_bh() and rcu_read_unlock_bh(), + or any pair of primitives that disables and re-enables preemption, + for example, rcu_read_lock_sched() and rcu_read_unlock_sched(). + If the updater uses synchronize_srcu() or call_srcu(), + then the corresponding readers must use srcu_read_lock() and srcu_read_unlock(), and with the same srcu_struct. The rules for the expedited primitives are the same as for their non-expedited counterparts. Mixing things up will result in confusion and - broken kernels. + broken kernels, and has even resulted in an exploitable security + issue. One exception to this rule: rcu_read_lock() and rcu_read_unlock() may be substituted for rcu_read_lock_bh() and rcu_read_unlock_bh() @@ -288,8 +285,7 @@ over a rather long period of time, but improvements are always welcome! d. Periodically invoke synchronize_rcu(), permitting a limited number of updates per grace period. - The same cautions apply to call_rcu_bh(), call_rcu_sched(), - call_srcu(), and kfree_rcu(). + The same cautions apply to call_srcu() and kfree_rcu(). Note that although these primitives do take action to avoid memory exhaustion when any given CPU has too many callbacks, a determined @@ -322,7 +318,7 @@ over a rather long period of time, but improvements are always welcome! 11. Any lock acquired by an RCU callback must be acquired elsewhere with softirq disabled, e.g., via spin_lock_irqsave(), - spin_lock_bh(), etc. Failing to disable irq on a given + spin_lock_bh(), etc. Failing to disable softirq on a given acquisition of that lock will result in deadlock as soon as the RCU softirq handler happens to run your RCU callback while interrupting that acquisition's critical section. @@ -335,13 +331,16 @@ over a rather long period of time, but improvements are always welcome! must use whatever locking or other synchronization is required to safely access and/or modify that data structure. - RCU callbacks are -usually- executed on the same CPU that executed - the corresponding call_rcu(), call_rcu_bh(), or call_rcu_sched(), - but are by -no- means guaranteed to be. For example, if a given - CPU goes offline while having an RCU callback pending, then that - RCU callback will execute on some surviving CPU. (If this was - not the case, a self-spawning RCU callback would prevent the - victim CPU from ever going offline.) + Do not assume that RCU callbacks will be executed on the same + CPU that executed the corresponding call_rcu() or call_srcu(). + For example, if a given CPU goes offline while having an RCU + callback pending, then that RCU callback will execute on some + surviving CPU. (If this was not the case, a self-spawning RCU + callback would prevent the victim CPU from ever going offline.) + Furthermore, CPUs designated by rcu_nocbs= might well -always- + have their RCU callbacks executed on some other CPUs, in fact, + for some real-time workloads, this is the whole point of using + the rcu_nocbs= kernel boot parameter. 13. Unlike other forms of RCU, it -is- permissible to block in an SRCU read-side critical section (demarked by srcu_read_lock() @@ -381,11 +380,11 @@ over a rather long period of time, but improvements are always welcome! SRCU's expedited primitive (synchronize_srcu_expedited()) never sends IPIs to other CPUs, so it is easier on - real-time workloads than is synchronize_rcu_expedited(), - synchronize_rcu_bh_expedited() or synchronize_sched_expedited(). + real-time workloads than is synchronize_rcu_expedited(). - Note that rcu_dereference() and rcu_assign_pointer() relate to - SRCU just as they do to other forms of RCU. + Note that rcu_assign_pointer() relates to SRCU just as it does to + other forms of RCU, but instead of rcu_dereference() you should + use srcu_dereference() in order to avoid lockdep splats. 14. The whole point of call_rcu(), synchronize_rcu(), and friends is to wait until all pre-existing readers have finished before @@ -405,6 +404,9 @@ over a rather long period of time, but improvements are always welcome! read-side critical sections. It is the responsibility of the RCU update-side primitives to deal with this. + For SRCU readers, you can use smp_mb__after_srcu_read_unlock() + immediately after an srcu_read_unlock() to get a full barrier. + 16. Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the __rcu sparse checks to validate your RCU code. These can help find problems as follows: @@ -428,22 +430,19 @@ over a rather long period of time, but improvements are always welcome! These debugging aids can help you find problems that are otherwise extremely difficult to spot. -17. If you register a callback using call_rcu(), call_rcu_bh(), - call_rcu_sched(), or call_srcu(), and pass in a function defined - within a loadable module, then it in necessary to wait for - all pending callbacks to be invoked after the last invocation - and before unloading that module. Note that it is absolutely - -not- sufficient to wait for a grace period! The current (say) - synchronize_rcu() implementation waits only for all previous - callbacks registered on the CPU that synchronize_rcu() is running - on, but it is -not- guaranteed to wait for callbacks registered - on other CPUs. +17. If you register a callback using call_rcu() or call_srcu(), and + pass in a function defined within a loadable module, then it in + necessary to wait for all pending callbacks to be invoked after + the last invocation and before unloading that module. Note that + it is absolutely -not- sufficient to wait for a grace period! + The current (say) synchronize_rcu() implementation is -not- + guaranteed to wait for callbacks registered on other CPUs. + Or even on the current CPU if that CPU recently went offline + and came back online. You instead need to use one of the barrier functions: o call_rcu() -> rcu_barrier() - o call_rcu_bh() -> rcu_barrier() - o call_rcu_sched() -> rcu_barrier() o call_srcu() -> srcu_barrier() However, these barrier functions are absolutely -not- guaranteed diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt index 721b3e426515..c818cf65c5a9 100644 --- a/Documentation/RCU/rcu.txt +++ b/Documentation/RCU/rcu.txt @@ -52,10 +52,10 @@ o If I am running on a uniprocessor kernel, which can only do one o How can I see where RCU is currently used in the Linux kernel? Search for "rcu_read_lock", "rcu_read_unlock", "call_rcu", - "rcu_read_lock_bh", "rcu_read_unlock_bh", "call_rcu_bh", - "srcu_read_lock", "srcu_read_unlock", "synchronize_rcu", - "synchronize_net", "synchronize_srcu", and the other RCU - primitives. Or grab one of the cscope databases from: + "rcu_read_lock_bh", "rcu_read_unlock_bh", "srcu_read_lock", + "srcu_read_unlock", "synchronize_rcu", "synchronize_net", + "synchronize_srcu", and the other RCU primitives. Or grab one + of the cscope databases from: http://www.rdrop.com/users/paulmck/RCU/linuxusage/rculocktab.html diff --git a/Documentation/RCU/rcu_dereference.txt b/Documentation/RCU/rcu_dereference.txt index ab96227bad42..bf699e8cfc75 100644 --- a/Documentation/RCU/rcu_dereference.txt +++ b/Documentation/RCU/rcu_dereference.txt @@ -351,3 +351,106 @@ garbage values. In short, rcu_dereference() is -not- optional when you are going to dereference the resulting pointer. + + +WHICH MEMBER OF THE rcu_dereference() FAMILY SHOULD YOU USE? + +First, please avoid using rcu_dereference_raw() and also please avoid +using rcu_dereference_check() and rcu_dereference_protected() with a +second argument with a constant value of 1 (or true, for that matter). +With that caution out of the way, here is some guidance for which +member of the rcu_dereference() to use in various situations: + +1. If the access needs to be within an RCU read-side critical + section, use rcu_dereference(). With the new consolidated + RCU flavors, an RCU read-side critical section is entered + using rcu_read_lock(), anything that disables bottom halves, + anything that disables interrupts, or anything that disables + preemption. + +2. If the access might be within an RCU read-side critical section + on the one hand, or protected by (say) my_lock on the other, + use rcu_dereference_check(), for example: + + p1 = rcu_dereference_check(p->rcu_protected_pointer, + lockdep_is_held(&my_lock)); + + +3. If the access might be within an RCU read-side critical section + on the one hand, or protected by either my_lock or your_lock on + the other, again use rcu_dereference_check(), for example: + + p1 = rcu_dereference_check(p->rcu_protected_pointer, + lockdep_is_held(&my_lock) || + lockdep_is_held(&your_lock)); + +4. If the access is on the update side, so that it is always protected + by my_lock, use rcu_dereference_protected(): + + p1 = rcu_dereference_protected(p->rcu_protected_pointer, + lockdep_is_held(&my_lock)); + + This can be extended to handle multiple locks as in #3 above, + and both can be extended to check other conditions as well. + +5. If the protection is supplied by the caller, and is thus unknown + to this code, that is the rare case when rcu_dereference_raw() + is appropriate. In addition, rcu_dereference_raw() might be + appropriate when the lockdep expression would be excessively + complex, except that a better approach in that case might be to + take a long hard look at your synchronization design. Still, + there are data-locking cases where any one of a very large number + of locks or reference counters suffices to protect the pointer, + so rcu_dereference_raw() does have its place. + + However, its place is probably quite a bit smaller than one + might expect given the number of uses in the current kernel. + Ditto for its synonym, rcu_dereference_check( ... , 1), and + its close relative, rcu_dereference_protected(... , 1). + + +SPARSE CHECKING OF RCU-PROTECTED POINTERS + +The sparse static-analysis tool checks for direct access to RCU-protected +pointers, which can result in "interesting" bugs due to compiler +optimizations involving invented loads and perhaps also load tearing. +For example, suppose someone mistakenly does something like this: + + p = q->rcu_protected_pointer; + do_something_with(p->a); + do_something_else_with(p->b); + +If register pressure is high, the compiler might optimize "p" out +of existence, transforming the code to something like this: + + do_something_with(q->rcu_protected_pointer->a); + do_something_else_with(q->rcu_protected_pointer->b); + +This could fatally disappoint your code if q->rcu_protected_pointer +changed in the meantime. Nor is this a theoretical problem: Exactly +this sort of bug cost Paul E. McKenney (and several of his innocent +colleagues) a three-day weekend back in the early 1990s. + +Load tearing could of course result in dereferencing a mashup of a pair +of pointers, which also might fatally disappoint your code. + +These problems could have been avoided simply by making the code instead +read as follows: + + p = rcu_dereference(q->rcu_protected_pointer); + do_something_with(p->a); + do_something_else_with(p->b); + +Unfortunately, these sorts of bugs can be extremely hard to spot during +review. This is where the sparse tool comes into play, along with the +"__rcu" marker. If you mark a pointer declaration, whether in a structure +or as a formal parameter, with "__rcu", which tells sparse to complain if +this pointer is accessed directly. It will also cause sparse to complain +if a pointer not marked with "__rcu" is accessed using rcu_dereference() +and friends. For example, ->rcu_protected_pointer might be declared as +follows: + + struct foo __rcu *rcu_protected_pointer; + +Use of "__rcu" is opt-in. If you choose not to use it, then you should +ignore the sparse warnings. diff --git a/Documentation/RCU/rcubarrier.txt b/Documentation/RCU/rcubarrier.txt index 5d7759071a3e..a2782df69732 100644 --- a/Documentation/RCU/rcubarrier.txt +++ b/Documentation/RCU/rcubarrier.txt @@ -83,16 +83,15 @@ Pseudo-code using rcu_barrier() is as follows: 2. Execute rcu_barrier(). 3. Allow the module to be unloaded. -There are also rcu_barrier_bh(), rcu_barrier_sched(), and srcu_barrier() -functions for the other flavors of RCU, and you of course must match -the flavor of rcu_barrier() with that of call_rcu(). If your module -uses multiple flavors of call_rcu(), then it must also use multiple +There is also an srcu_barrier() function for SRCU, and you of course +must match the flavor of rcu_barrier() with that of call_rcu(). If your +module uses multiple flavors of call_rcu(), then it must also use multiple flavors of rcu_barrier() when unloading that module. For example, if -it uses call_rcu_bh(), call_srcu() on srcu_struct_1, and call_srcu() on +it uses call_rcu(), call_srcu() on srcu_struct_1, and call_srcu() on srcu_struct_2(), then the following three lines of code will be required when unloading: - 1 rcu_barrier_bh(); + 1 rcu_barrier(); 2 srcu_barrier(&srcu_struct_1); 3 srcu_barrier(&srcu_struct_2); @@ -185,12 +184,12 @@ module invokes call_rcu() from timers, you will need to first cancel all the timers, and only then invoke rcu_barrier() to wait for any remaining RCU callbacks to complete. -Of course, if you module uses call_rcu_bh(), you will need to invoke -rcu_barrier_bh() before unloading. Similarly, if your module uses -call_rcu_sched(), you will need to invoke rcu_barrier_sched() before -unloading. If your module uses call_rcu(), call_rcu_bh(), -and- -call_rcu_sched(), then you will need to invoke each of rcu_barrier(), -rcu_barrier_bh(), and rcu_barrier_sched(). +Of course, if you module uses call_rcu(), you will need to invoke +rcu_barrier() before unloading. Similarly, if your module uses +call_srcu(), you will need to invoke srcu_barrier() before unloading, +and on the same srcu_struct structure. If your module uses call_rcu() +-and- call_srcu(), then you will need to invoke rcu_barrier() -and- +srcu_barrier(). Implementing rcu_barrier() @@ -223,8 +222,8 @@ shown below. Note that the final "1" in on_each_cpu()'s argument list ensures that all the calls to rcu_barrier_func() will have completed before on_each_cpu() returns. Line 9 then waits for the completion. -This code was rewritten in 2008 to support rcu_barrier_bh() and -rcu_barrier_sched() in addition to the original rcu_barrier(). +This code was rewritten in 2008 and several times thereafter, but this +still gives the general idea. The rcu_barrier_func() runs on each CPU, where it invokes call_rcu() to post an RCU callback, as follows: diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 1ace20815bb1..981651a8b65d 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -310,7 +310,7 @@ reader, updater, and reclaimer. rcu_assign_pointer() - +--------+ + +--------+ +---------------------->| reader |---------+ | +--------+ | | | | @@ -318,12 +318,12 @@ reader, updater, and reclaimer. | | | rcu_read_lock() | | | rcu_read_unlock() | rcu_dereference() | | - +---------+ | | - | updater |<---------------------+ | - +---------+ V + +---------+ | | + | updater |<----------------+ | + +---------+ V | +-----------+ +----------------------------------->| reclaimer | - +-----------+ + +-----------+ Defer: synchronize_rcu() & call_rcu() diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2b8ee90bb644..d377a2166b79 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3623,7 +3623,9 @@ see CONFIG_RAS_CEC help text. rcu_nocbs= [KNL] - The argument is a cpu list, as described above. + The argument is a cpu list, as described above, + except that the string "all" can be used to + specify every CPU on the system. In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. diff --git a/MAINTAINERS b/MAINTAINERS index e17ebf70b548..a9b5270d006e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8983,7 +8983,7 @@ R: Daniel Lustig L: linux-kernel@vger.kernel.org L: linux-arch@vger.kernel.org S: Supported -T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git +T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev F: tools/memory-model/ F: Documentation/atomic_bitops.txt F: Documentation/atomic_t.txt @@ -13031,9 +13031,9 @@ M: Josh Triplett R: Steven Rostedt R: Mathieu Desnoyers R: Lai Jiangshan -L: linux-kernel@vger.kernel.org +L: rcu@vger.kernel.org S: Supported -T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git +T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev F: tools/testing/selftests/rcutorture RDC R-321X SoC @@ -13079,10 +13079,10 @@ R: Steven Rostedt R: Mathieu Desnoyers R: Lai Jiangshan R: Joel Fernandes -L: linux-kernel@vger.kernel.org +L: rcu@vger.kernel.org W: http://www.rdrop.com/users/paulmck/RCU/ S: Supported -T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git +T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev F: Documentation/RCU/ X: Documentation/RCU/torture.txt F: include/linux/rcu* @@ -14234,10 +14234,10 @@ M: "Paul E. McKenney" M: Josh Triplett R: Steven Rostedt R: Mathieu Desnoyers -L: linux-kernel@vger.kernel.org +L: rcu@vger.kernel.org W: http://www.rdrop.com/users/paulmck/RCU/ S: Supported -T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git +T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev F: include/linux/srcu*.h F: kernel/rcu/srcu*.c @@ -15684,7 +15684,7 @@ M: "Paul E. McKenney" M: Josh Triplett L: linux-kernel@vger.kernel.org S: Supported -T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git +T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev F: Documentation/RCU/torture.txt F: kernel/torture.c F: kernel/rcu/rcutorture.c diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 470601980794..739c5b4830d7 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -388,7 +388,7 @@ static void nvme_free_ns_head(struct kref *ref) nvme_mpath_remove_disk(head); ida_simple_remove(&head->subsys->ns_ida, head->instance); list_del_init(&head->entry); - cleanup_srcu_struct_quiesced(&head->srcu); + cleanup_srcu_struct(&head->srcu); nvme_put_subsystem(head->subsys); kfree(head); } diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 6cdb1db776cf..922bb6848813 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -878,9 +878,11 @@ static inline void rcu_head_init(struct rcu_head *rhp) static inline bool rcu_head_after_call_rcu(struct rcu_head *rhp, rcu_callback_t f) { - if (READ_ONCE(rhp->func) == f) + rcu_callback_t func = READ_ONCE(rhp->func); + + if (func == f) return true; - WARN_ON_ONCE(READ_ONCE(rhp->func) != (rcu_callback_t)~0L); + WARN_ON_ONCE(func != (rcu_callback_t)~0L); return false; } diff --git a/include/linux/srcu.h b/include/linux/srcu.h index c495b2d51569..e432cc92c73d 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -56,45 +56,11 @@ struct srcu_struct { }; void call_srcu(struct srcu_struct *ssp, struct rcu_head *head, void (*func)(struct rcu_head *head)); -void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced); +void cleanup_srcu_struct(struct srcu_struct *ssp); int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp); void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp); void synchronize_srcu(struct srcu_struct *ssp); -/** - * cleanup_srcu_struct - deconstruct a sleep-RCU structure - * @ssp: structure to clean up. - * - * Must invoke this after you are finished using a given srcu_struct that - * was initialized via init_srcu_struct(), else you leak memory. - */ -static inline void cleanup_srcu_struct(struct srcu_struct *ssp) -{ - _cleanup_srcu_struct(ssp, false); -} - -/** - * cleanup_srcu_struct_quiesced - deconstruct a quiesced sleep-RCU structure - * @ssp: structure to clean up. - * - * Must invoke this after you are finished using a given srcu_struct that - * was initialized via init_srcu_struct(), else you leak memory. Also, - * all grace-period processing must have completed. - * - * "Completed" means that the last synchronize_srcu() and - * synchronize_srcu_expedited() calls must have returned before the call - * to cleanup_srcu_struct_quiesced(). It also means that the callback - * from the last call_srcu() must have been invoked before the call to - * cleanup_srcu_struct_quiesced(), but you can use srcu_barrier() to help - * with this last. Violating these rules will get you a WARN_ON() splat - * (with high probability, anyway), and will also cause the srcu_struct - * to be leaked. - */ -static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *ssp) -{ - _cleanup_srcu_struct(ssp, true); -} - #ifdef CONFIG_DEBUG_LOCK_ALLOC /** diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index ad40a2617063..80a463d31a8d 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -829,7 +829,9 @@ static void lock_torture_cleanup(void) "End of test: SUCCESS"); kfree(cxt.lwsa); + cxt.lwsa = NULL; kfree(cxt.lrsa); + cxt.lrsa = NULL; end: torture_cleanup_end(); diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index acee72c0b24b..4b58c907b4b7 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -233,6 +233,7 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) #ifdef CONFIG_RCU_STALL_COMMON extern int rcu_cpu_stall_suppress; +extern int rcu_cpu_stall_timeout; int rcu_jiffies_till_stall_check(void); #define rcu_ftrace_dump_stall_suppress() \ diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index c29761152874..7a6890b23c5f 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -494,6 +494,10 @@ rcu_perf_cleanup(void) if (torture_cleanup_begin()) return; + if (!cur_ops) { + torture_cleanup_end(); + return; + } if (reader_tasks) { for (i = 0; i < nrealreaders; i++) @@ -614,6 +618,7 @@ rcu_perf_init(void) pr_cont("\n"); WARN_ON(!IS_MODULE(CONFIG_RCU_PERF_TEST)); firsterr = -EINVAL; + cur_ops = NULL; goto unwind; } if (cur_ops->init) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index f14d1b18a74f..efaa5b3f4d3f 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -299,7 +299,6 @@ struct rcu_torture_ops { int irq_capable; int can_boost; int extendables; - int ext_irq_conflict; const char *name; }; @@ -592,12 +591,7 @@ static void srcu_torture_init(void) static void srcu_torture_cleanup(void) { - static DEFINE_TORTURE_RANDOM(rand); - - if (torture_random(&rand) & 0x800) - cleanup_srcu_struct(&srcu_ctld); - else - cleanup_srcu_struct_quiesced(&srcu_ctld); + cleanup_srcu_struct(&srcu_ctld); srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */ } @@ -1160,7 +1154,7 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp) unsigned long randmask2 = randmask1 >> 3; WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT); - /* Most of the time lots of bits, half the time only one bit. */ + /* Mostly only one bit (need preemption!), sometimes lots of bits. */ if (!(randmask1 & 0x7)) mask = mask & randmask2; else @@ -1170,10 +1164,6 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp) ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) || (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH)))) mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH; - if ((mask & RCUTORTURE_RDR_IRQ) && - !(mask & cur_ops->ext_irq_conflict) && - (oldmask & cur_ops->ext_irq_conflict)) - mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */ return mask ?: RCUTORTURE_RDR_RCU; } @@ -1848,7 +1838,7 @@ static int rcutorture_oom_notify(struct notifier_block *self, WARN(1, "%s invoked upon OOM during forward-progress testing.\n", __func__); rcu_torture_fwd_cb_hist(); - rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2)); + rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2); WRITE_ONCE(rcu_fwd_emergency_stop, true); smp_mb(); /* Emergency stop before free and wait to avoid hangs. */ pr_info("%s: Freed %lu RCU callbacks.\n", @@ -2094,6 +2084,10 @@ rcu_torture_cleanup(void) cur_ops->cb_barrier(); return; } + if (!cur_ops) { + torture_cleanup_end(); + return; + } rcu_torture_barrier_cleanup(); torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task); @@ -2267,6 +2261,7 @@ rcu_torture_init(void) pr_cont("\n"); WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST)); firsterr = -EINVAL; + cur_ops = NULL; goto unwind; } if (cur_ops->fqs == NULL && fqs_duration != 0) { diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index 5d4a39a6505a..44d6606b8325 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -76,19 +76,16 @@ EXPORT_SYMBOL_GPL(init_srcu_struct); * Must invoke this after you are finished using a given srcu_struct that * was initialized via init_srcu_struct(), else you leak memory. */ -void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced) +void cleanup_srcu_struct(struct srcu_struct *ssp) { WARN_ON(ssp->srcu_lock_nesting[0] || ssp->srcu_lock_nesting[1]); - if (quiesced) - WARN_ON(work_pending(&ssp->srcu_work)); - else - flush_work(&ssp->srcu_work); + flush_work(&ssp->srcu_work); WARN_ON(ssp->srcu_gp_running); WARN_ON(ssp->srcu_gp_waiting); WARN_ON(ssp->srcu_cb_head); WARN_ON(&ssp->srcu_cb_head != ssp->srcu_cb_tail); } -EXPORT_SYMBOL_GPL(_cleanup_srcu_struct); +EXPORT_SYMBOL_GPL(cleanup_srcu_struct); /* * Removes the count for the old reader from the appropriate element of diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index a60b8ba9e1ac..9b761e546de8 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -360,8 +360,14 @@ static unsigned long srcu_get_delay(struct srcu_struct *ssp) return SRCU_INTERVAL; } -/* Helper for cleanup_srcu_struct() and cleanup_srcu_struct_quiesced(). */ -void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced) +/** + * cleanup_srcu_struct - deconstruct a sleep-RCU structure + * @ssp: structure to clean up. + * + * Must invoke this after you are finished using a given srcu_struct that + * was initialized via init_srcu_struct(), else you leak memory. + */ +void cleanup_srcu_struct(struct srcu_struct *ssp) { int cpu; @@ -369,24 +375,14 @@ void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced) return; /* Just leak it! */ if (WARN_ON(srcu_readers_active(ssp))) return; /* Just leak it! */ - if (quiesced) { - if (WARN_ON(delayed_work_pending(&ssp->work))) - return; /* Just leak it! */ - } else { - flush_delayed_work(&ssp->work); - } + flush_delayed_work(&ssp->work); for_each_possible_cpu(cpu) { struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); - if (quiesced) { - if (WARN_ON(timer_pending(&sdp->delay_work))) - return; /* Just leak it! */ - if (WARN_ON(work_pending(&sdp->work))) - return; /* Just leak it! */ - } else { - del_timer_sync(&sdp->delay_work); - flush_work(&sdp->work); - } + del_timer_sync(&sdp->delay_work); + flush_work(&sdp->work); + if (WARN_ON(rcu_segcblist_n_cbs(&sdp->srcu_cblist))) + return; /* Forgot srcu_barrier(), so just leak it! */ } if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) || WARN_ON(srcu_readers_active(ssp))) { @@ -397,7 +393,7 @@ void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced) free_percpu(ssp->sda); ssp->sda = NULL; } -EXPORT_SYMBOL_GPL(_cleanup_srcu_struct); +EXPORT_SYMBOL_GPL(cleanup_srcu_struct); /* * Counts the new reader in the appropriate per-CPU element of the diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index 911bd9076d43..477b4eb44af5 100644 --- a/kernel/rcu/tiny.c +++ b/kernel/rcu/tiny.c @@ -52,7 +52,7 @@ void rcu_qs(void) local_irq_save(flags); if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) { rcu_ctrlblk.donetail = rcu_ctrlblk.curtail; - raise_softirq(RCU_SOFTIRQ); + raise_softirq_irqoff(RCU_SOFTIRQ); } local_irq_restore(flags); } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index acd6ccf56faf..ec77ec336f58 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -102,11 +102,6 @@ int rcu_num_lvls __read_mostly = RCU_NUM_LVLS; /* Number of rcu_nodes at specified level. */ int num_rcu_lvl[] = NUM_RCU_LVL_INIT; int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */ -/* panic() on RCU Stall sysctl. */ -int sysctl_panic_on_rcu_stall __read_mostly; -/* Commandeer a sysrq key to dump RCU's tree. */ -static bool sysrq_rcu; -module_param(sysrq_rcu, bool, 0444); /* * The rcu_scheduler_active variable is initialized to the value @@ -149,7 +144,7 @@ static void sync_sched_exp_online_cleanup(int cpu); /* rcuc/rcub kthread realtime priority */ static int kthread_prio = IS_ENABLED(CONFIG_RCU_BOOST) ? 1 : 0; -module_param(kthread_prio, int, 0644); +module_param(kthread_prio, int, 0444); /* Delay in jiffies for grace-period initialization delays, debug only. */ @@ -406,7 +401,7 @@ static bool rcu_kick_kthreads; */ static ulong jiffies_till_sched_qs = ULONG_MAX; module_param(jiffies_till_sched_qs, ulong, 0444); -static ulong jiffies_to_sched_qs; /* Adjusted version of above if not default */ +static ulong jiffies_to_sched_qs; /* See adjust_jiffies_till_sched_qs(). */ module_param(jiffies_to_sched_qs, ulong, 0444); /* Display only! */ /* @@ -424,6 +419,7 @@ static void adjust_jiffies_till_sched_qs(void) WRITE_ONCE(jiffies_to_sched_qs, jiffies_till_sched_qs); return; } + /* Otherwise, set to third fqs scan, but bound below on large system. */ j = READ_ONCE(jiffies_till_first_fqs) + 2 * READ_ONCE(jiffies_till_next_fqs); if (j < HZ / 10 + nr_cpu_ids / RCU_JIFFIES_FQS_DIV) @@ -512,74 +508,6 @@ static const char *gp_state_getname(short gs) return gp_state_names[gs]; } -/* - * Show the state of the grace-period kthreads. - */ -void show_rcu_gp_kthreads(void) -{ - int cpu; - unsigned long j; - unsigned long ja; - unsigned long jr; - unsigned long jw; - struct rcu_data *rdp; - struct rcu_node *rnp; - - j = jiffies; - ja = j - READ_ONCE(rcu_state.gp_activity); - jr = j - READ_ONCE(rcu_state.gp_req_activity); - jw = j - READ_ONCE(rcu_state.gp_wake_time); - pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n", - rcu_state.name, gp_state_getname(rcu_state.gp_state), - rcu_state.gp_state, - rcu_state.gp_kthread ? rcu_state.gp_kthread->state : 0x1ffffL, - ja, jr, jw, (long)READ_ONCE(rcu_state.gp_wake_seq), - (long)READ_ONCE(rcu_state.gp_seq), - (long)READ_ONCE(rcu_get_root()->gp_seq_needed), - READ_ONCE(rcu_state.gp_flags)); - rcu_for_each_node_breadth_first(rnp) { - if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed)) - continue; - pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld\n", - rnp->grplo, rnp->grphi, (long)rnp->gp_seq, - (long)rnp->gp_seq_needed); - if (!rcu_is_leaf_node(rnp)) - continue; - for_each_leaf_node_possible_cpu(rnp, cpu) { - rdp = per_cpu_ptr(&rcu_data, cpu); - if (rdp->gpwrap || - ULONG_CMP_GE(rcu_state.gp_seq, - rdp->gp_seq_needed)) - continue; - pr_info("\tcpu %d ->gp_seq_needed %ld\n", - cpu, (long)rdp->gp_seq_needed); - } - } - /* sched_show_task(rcu_state.gp_kthread); */ -} -EXPORT_SYMBOL_GPL(show_rcu_gp_kthreads); - -/* Dump grace-period-request information due to commandeered sysrq. */ -static void sysrq_show_rcu(int key) -{ - show_rcu_gp_kthreads(); -} - -static struct sysrq_key_op sysrq_rcudump_op = { - .handler = sysrq_show_rcu, - .help_msg = "show-rcu(y)", - .action_msg = "Show RCU tree", - .enable_mask = SYSRQ_ENABLE_DUMP, -}; - -static int __init rcu_sysrq_init(void) -{ - if (sysrq_rcu) - return register_sysrq_key('y', &sysrq_rcudump_op); - return 0; -} -early_initcall(rcu_sysrq_init); - /* * Send along grace-period-related data for rcutorture diagnostics. */ @@ -1033,27 +961,6 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp) return 0; } -/* - * Handler for the irq_work request posted when a grace period has - * gone on for too long, but not yet long enough for an RCU CPU - * stall warning. Set state appropriately, but just complain if - * there is unexpected state on entry. - */ -static void rcu_iw_handler(struct irq_work *iwp) -{ - struct rcu_data *rdp; - struct rcu_node *rnp; - - rdp = container_of(iwp, struct rcu_data, rcu_iw); - rnp = rdp->mynode; - raw_spin_lock_rcu_node(rnp); - if (!WARN_ON_ONCE(!rdp->rcu_iw_pending)) { - rdp->rcu_iw_gp_seq = rnp->gp_seq; - rdp->rcu_iw_pending = false; - } - raw_spin_unlock_rcu_node(rnp); -} - /* * Return true if the specified CPU has passed through a quiescent * state by virtue of being in or having passed through an dynticks @@ -1167,295 +1074,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) return 0; } -static void record_gp_stall_check_time(void) -{ - unsigned long j = jiffies; - unsigned long j1; - - rcu_state.gp_start = j; - j1 = rcu_jiffies_till_stall_check(); - /* Record ->gp_start before ->jiffies_stall. */ - smp_store_release(&rcu_state.jiffies_stall, j + j1); /* ^^^ */ - rcu_state.jiffies_resched = j + j1 / 2; - rcu_state.n_force_qs_gpstart = READ_ONCE(rcu_state.n_force_qs); -} - -/* - * Complain about starvation of grace-period kthread. - */ -static void rcu_check_gp_kthread_starvation(void) -{ - struct task_struct *gpk = rcu_state.gp_kthread; - unsigned long j; - - j = jiffies - READ_ONCE(rcu_state.gp_activity); - if (j > 2 * HZ) { - pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#lx ->cpu=%d\n", - rcu_state.name, j, - (long)rcu_seq_current(&rcu_state.gp_seq), - READ_ONCE(rcu_state.gp_flags), - gp_state_getname(rcu_state.gp_state), rcu_state.gp_state, - gpk ? gpk->state : ~0, gpk ? task_cpu(gpk) : -1); - if (gpk) { - pr_err("RCU grace-period kthread stack dump:\n"); - sched_show_task(gpk); - wake_up_process(gpk); - } - } -} - -/* - * Dump stacks of all tasks running on stalled CPUs. First try using - * NMIs, but fall back to manual remote stack tracing on architectures - * that don't support NMI-based stack dumps. The NMI-triggered stack - * traces are more accurate because they are printed by the target CPU. - */ -static void rcu_dump_cpu_stacks(void) -{ - int cpu; - unsigned long flags; - struct rcu_node *rnp; - - rcu_for_each_leaf_node(rnp) { - raw_spin_lock_irqsave_rcu_node(rnp, flags); - for_each_leaf_node_possible_cpu(rnp, cpu) - if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - } -} - -/* - * If too much time has passed in the current grace period, and if - * so configured, go kick the relevant kthreads. - */ -static void rcu_stall_kick_kthreads(void) -{ - unsigned long j; - - if (!rcu_kick_kthreads) - return; - j = READ_ONCE(rcu_state.jiffies_kick_kthreads); - if (time_after(jiffies, j) && rcu_state.gp_kthread && - (rcu_gp_in_progress() || READ_ONCE(rcu_state.gp_flags))) { - WARN_ONCE(1, "Kicking %s grace-period kthread\n", - rcu_state.name); - rcu_ftrace_dump(DUMP_ALL); - wake_up_process(rcu_state.gp_kthread); - WRITE_ONCE(rcu_state.jiffies_kick_kthreads, j + HZ); - } -} - -static void panic_on_rcu_stall(void) -{ - if (sysctl_panic_on_rcu_stall) - panic("RCU Stall\n"); -} - -static void print_other_cpu_stall(unsigned long gp_seq) -{ - int cpu; - unsigned long flags; - unsigned long gpa; - unsigned long j; - int ndetected = 0; - struct rcu_node *rnp = rcu_get_root(); - long totqlen = 0; - - /* Kick and suppress, if so configured. */ - rcu_stall_kick_kthreads(); - if (rcu_cpu_stall_suppress) - return; - - /* - * OK, time to rat on our buddy... - * See Documentation/RCU/stallwarn.txt for info on how to debug - * RCU CPU stall warnings. - */ - pr_err("INFO: %s detected stalls on CPUs/tasks:", rcu_state.name); - print_cpu_stall_info_begin(); - rcu_for_each_leaf_node(rnp) { - raw_spin_lock_irqsave_rcu_node(rnp, flags); - ndetected += rcu_print_task_stall(rnp); - if (rnp->qsmask != 0) { - for_each_leaf_node_possible_cpu(rnp, cpu) - if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) { - print_cpu_stall_info(cpu); - ndetected++; - } - } - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - } - - print_cpu_stall_info_end(); - for_each_possible_cpu(cpu) - totqlen += rcu_get_n_cbs_cpu(cpu); - pr_cont("(detected by %d, t=%ld jiffies, g=%ld, q=%lu)\n", - smp_processor_id(), (long)(jiffies - rcu_state.gp_start), - (long)rcu_seq_current(&rcu_state.gp_seq), totqlen); - if (ndetected) { - rcu_dump_cpu_stacks(); - - /* Complain about tasks blocking the grace period. */ - rcu_print_detail_task_stall(); - } else { - if (rcu_seq_current(&rcu_state.gp_seq) != gp_seq) { - pr_err("INFO: Stall ended before state dump start\n"); - } else { - j = jiffies; - gpa = READ_ONCE(rcu_state.gp_activity); - pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n", - rcu_state.name, j - gpa, j, gpa, - READ_ONCE(jiffies_till_next_fqs), - rcu_get_root()->qsmask); - /* In this case, the current CPU might be at fault. */ - sched_show_task(current); - } - } - /* Rewrite if needed in case of slow consoles. */ - if (ULONG_CMP_GE(jiffies, READ_ONCE(rcu_state.jiffies_stall))) - WRITE_ONCE(rcu_state.jiffies_stall, - jiffies + 3 * rcu_jiffies_till_stall_check() + 3); - - rcu_check_gp_kthread_starvation(); - - panic_on_rcu_stall(); - - rcu_force_quiescent_state(); /* Kick them all. */ -} - -static void print_cpu_stall(void) -{ - int cpu; - unsigned long flags; - struct rcu_data *rdp = this_cpu_ptr(&rcu_data); - struct rcu_node *rnp = rcu_get_root(); - long totqlen = 0; - - /* Kick and suppress, if so configured. */ - rcu_stall_kick_kthreads(); - if (rcu_cpu_stall_suppress) - return; - - /* - * OK, time to rat on ourselves... - * See Documentation/RCU/stallwarn.txt for info on how to debug - * RCU CPU stall warnings. - */ - pr_err("INFO: %s self-detected stall on CPU", rcu_state.name); - print_cpu_stall_info_begin(); - raw_spin_lock_irqsave_rcu_node(rdp->mynode, flags); - print_cpu_stall_info(smp_processor_id()); - raw_spin_unlock_irqrestore_rcu_node(rdp->mynode, flags); - print_cpu_stall_info_end(); - for_each_possible_cpu(cpu) - totqlen += rcu_get_n_cbs_cpu(cpu); - pr_cont(" (t=%lu jiffies g=%ld q=%lu)\n", - jiffies - rcu_state.gp_start, - (long)rcu_seq_current(&rcu_state.gp_seq), totqlen); - - rcu_check_gp_kthread_starvation(); - - rcu_dump_cpu_stacks(); - - raw_spin_lock_irqsave_rcu_node(rnp, flags); - /* Rewrite if needed in case of slow consoles. */ - if (ULONG_CMP_GE(jiffies, READ_ONCE(rcu_state.jiffies_stall))) - WRITE_ONCE(rcu_state.jiffies_stall, - jiffies + 3 * rcu_jiffies_till_stall_check() + 3); - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - - panic_on_rcu_stall(); - - /* - * Attempt to revive the RCU machinery by forcing a context switch. - * - * A context switch would normally allow the RCU state machine to make - * progress and it could be we're stuck in kernel space without context - * switches for an entirely unreasonable amount of time. - */ - set_tsk_need_resched(current); - set_preempt_need_resched(); -} - -static void check_cpu_stall(struct rcu_data *rdp) -{ - unsigned long gs1; - unsigned long gs2; - unsigned long gps; - unsigned long j; - unsigned long jn; - unsigned long js; - struct rcu_node *rnp; - - if ((rcu_cpu_stall_suppress && !rcu_kick_kthreads) || - !rcu_gp_in_progress()) - return; - rcu_stall_kick_kthreads(); - j = jiffies; - - /* - * Lots of memory barriers to reject false positives. - * - * The idea is to pick up rcu_state.gp_seq, then - * rcu_state.jiffies_stall, then rcu_state.gp_start, and finally - * another copy of rcu_state.gp_seq. These values are updated in - * the opposite order with memory barriers (or equivalent) during - * grace-period initialization and cleanup. Now, a false positive - * can occur if we get an new value of rcu_state.gp_start and a old - * value of rcu_state.jiffies_stall. But given the memory barriers, - * the only way that this can happen is if one grace period ends - * and another starts between these two fetches. This is detected - * by comparing the second fetch of rcu_state.gp_seq with the - * previous fetch from rcu_state.gp_seq. - * - * Given this check, comparisons of jiffies, rcu_state.jiffies_stall, - * and rcu_state.gp_start suffice to forestall false positives. - */ - gs1 = READ_ONCE(rcu_state.gp_seq); - smp_rmb(); /* Pick up ->gp_seq first... */ - js = READ_ONCE(rcu_state.jiffies_stall); - smp_rmb(); /* ...then ->jiffies_stall before the rest... */ - gps = READ_ONCE(rcu_state.gp_start); - smp_rmb(); /* ...and finally ->gp_start before ->gp_seq again. */ - gs2 = READ_ONCE(rcu_state.gp_seq); - if (gs1 != gs2 || - ULONG_CMP_LT(j, js) || - ULONG_CMP_GE(gps, js)) - return; /* No stall or GP completed since entering function. */ - rnp = rdp->mynode; - jn = jiffies + 3 * rcu_jiffies_till_stall_check() + 3; - if (rcu_gp_in_progress() && - (READ_ONCE(rnp->qsmask) & rdp->grpmask) && - cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) { - - /* We haven't checked in, so go dump stack. */ - print_cpu_stall(); - - } else if (rcu_gp_in_progress() && - ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY) && - cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) { - - /* They had a few time units to dump stack, so complain. */ - print_other_cpu_stall(gs2); - } -} - -/** - * rcu_cpu_stall_reset - prevent further stall warnings in current grace period - * - * Set the stall-warning timeout way off into the future, thus preventing - * any RCU CPU stall-warning messages from appearing in the current set of - * RCU grace periods. - * - * The caller must disable hard irqs. - */ -void rcu_cpu_stall_reset(void) -{ - WRITE_ONCE(rcu_state.jiffies_stall, jiffies + ULONG_MAX / 2); -} - /* Trace-event wrapper function for trace_rcu_future_grace_period. */ static void trace_rcu_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, unsigned long gp_seq_req, const char *s) @@ -1585,7 +1203,7 @@ static bool rcu_future_gp_cleanup(struct rcu_node *rnp) static void rcu_gp_kthread_wake(void) { if ((current == rcu_state.gp_kthread && - !in_interrupt() && !in_serving_softirq()) || + !in_irq() && !in_serving_softirq()) || !READ_ONCE(rcu_state.gp_flags) || !rcu_state.gp_kthread) return; @@ -2295,11 +1913,10 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp) return; } mask = rdp->grpmask; + rdp->core_needs_qs = false; if ((rnp->qsmask & mask) == 0) { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } else { - rdp->core_needs_qs = false; - /* * This GP can't end until cpu checks in, so all of our * callbacks can be processed during the next GP. @@ -2548,11 +2165,11 @@ void rcu_sched_clock_irq(int user) } /* - * Scan the leaf rcu_node structures, processing dyntick state for any that - * have not yet encountered a quiescent state, using the function specified. - * Also initiate boosting for any threads blocked on the root rcu_node. - * - * The caller must have suppressed start of new grace periods. + * Scan the leaf rcu_node structures. For each structure on which all + * CPUs have reported a quiescent state and on which there are tasks + * blocking the current grace period, initiate RCU priority boosting. + * Otherwise, invoke the specified function to check dyntick state for + * each CPU that has not yet reported a quiescent state. */ static void force_qs_rnp(int (*f)(struct rcu_data *rdp)) { @@ -2635,101 +2252,6 @@ void rcu_force_quiescent_state(void) } EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); -/* - * This function checks for grace-period requests that fail to motivate - * RCU to come out of its idle mode. - */ -void -rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp, - const unsigned long gpssdelay) -{ - unsigned long flags; - unsigned long j; - struct rcu_node *rnp_root = rcu_get_root(); - static atomic_t warned = ATOMIC_INIT(0); - - if (!IS_ENABLED(CONFIG_PROVE_RCU) || rcu_gp_in_progress() || - ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed)) - return; - j = jiffies; /* Expensive access, and in common case don't get here. */ - if (time_before(j, READ_ONCE(rcu_state.gp_req_activity) + gpssdelay) || - time_before(j, READ_ONCE(rcu_state.gp_activity) + gpssdelay) || - atomic_read(&warned)) - return; - - raw_spin_lock_irqsave_rcu_node(rnp, flags); - j = jiffies; - if (rcu_gp_in_progress() || - ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed) || - time_before(j, READ_ONCE(rcu_state.gp_req_activity) + gpssdelay) || - time_before(j, READ_ONCE(rcu_state.gp_activity) + gpssdelay) || - atomic_read(&warned)) { - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - return; - } - /* Hold onto the leaf lock to make others see warned==1. */ - - if (rnp_root != rnp) - raw_spin_lock_rcu_node(rnp_root); /* irqs already disabled. */ - j = jiffies; - if (rcu_gp_in_progress() || - ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed) || - time_before(j, rcu_state.gp_req_activity + gpssdelay) || - time_before(j, rcu_state.gp_activity + gpssdelay) || - atomic_xchg(&warned, 1)) { - raw_spin_unlock_rcu_node(rnp_root); /* irqs remain disabled. */ - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - return; - } - WARN_ON(1); - if (rnp_root != rnp) - raw_spin_unlock_rcu_node(rnp_root); - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - show_rcu_gp_kthreads(); -} - -/* - * Do a forward-progress check for rcutorture. This is normally invoked - * due to an OOM event. The argument "j" gives the time period during - * which rcutorture would like progress to have been made. - */ -void rcu_fwd_progress_check(unsigned long j) -{ - unsigned long cbs; - int cpu; - unsigned long max_cbs = 0; - int max_cpu = -1; - struct rcu_data *rdp; - - if (rcu_gp_in_progress()) { - pr_info("%s: GP age %lu jiffies\n", - __func__, jiffies - rcu_state.gp_start); - show_rcu_gp_kthreads(); - } else { - pr_info("%s: Last GP end %lu jiffies ago\n", - __func__, jiffies - rcu_state.gp_end); - preempt_disable(); - rdp = this_cpu_ptr(&rcu_data); - rcu_check_gp_start_stall(rdp->mynode, rdp, j); - preempt_enable(); - } - for_each_possible_cpu(cpu) { - cbs = rcu_get_n_cbs_cpu(cpu); - if (!cbs) - continue; - if (max_cpu < 0) - pr_info("%s: callbacks", __func__); - pr_cont(" %d: %lu", cpu, cbs); - if (cbs <= max_cbs) - continue; - max_cbs = cbs; - max_cpu = cpu; - } - if (max_cpu >= 0) - pr_cont("\n"); -} -EXPORT_SYMBOL_GPL(rcu_fwd_progress_check); - /* Perform RCU core processing work for the current CPU. */ static __latent_entropy void rcu_core(struct softirq_action *unused) { @@ -3559,13 +3081,11 @@ static int rcu_pm_notify(struct notifier_block *self, switch (action) { case PM_HIBERNATION_PREPARE: case PM_SUSPEND_PREPARE: - if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */ - rcu_expedite_gp(); + rcu_expedite_gp(); break; case PM_POST_HIBERNATION: case PM_POST_SUSPEND: - if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */ - rcu_unexpedite_gp(); + rcu_unexpedite_gp(); break; default: break; @@ -3742,8 +3262,7 @@ static void __init rcu_init_geometry(void) jiffies_till_first_fqs = d; if (jiffies_till_next_fqs == ULONG_MAX) jiffies_till_next_fqs = d; - if (jiffies_till_sched_qs == ULONG_MAX) - adjust_jiffies_till_sched_qs(); + adjust_jiffies_till_sched_qs(); /* If the compile-time values are accurate, just leave. */ if (rcu_fanout_leaf == RCU_FANOUT_LEAF && @@ -3858,5 +3377,6 @@ void __init rcu_init(void) srcu_init(); } +#include "tree_stall.h" #include "tree_exp.h" #include "tree_plugin.h" diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index bb4f995f2d3f..e253d11af3c4 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -393,15 +393,13 @@ static const char *tp_rcu_varname __used __tracepoint_string = rcu_name; int rcu_dynticks_snap(struct rcu_data *rdp); -/* Forward declarations for rcutree_plugin.h */ +/* Forward declarations for tree_plugin.h */ static void rcu_bootup_announce(void); static void rcu_qs(void); static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); #ifdef CONFIG_HOTPLUG_CPU static bool rcu_preempt_has_tasks(struct rcu_node *rnp); #endif /* #ifdef CONFIG_HOTPLUG_CPU */ -static void rcu_print_detail_task_stall(void); -static int rcu_print_task_stall(struct rcu_node *rnp); static int rcu_print_task_exp_stall(struct rcu_node *rnp); static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); static void rcu_flavor_sched_clock_irq(int user); @@ -418,9 +416,6 @@ static void rcu_prepare_for_idle(void); static bool rcu_preempt_has_tasks(struct rcu_node *rnp); static bool rcu_preempt_need_deferred_qs(struct task_struct *t); static void rcu_preempt_deferred_qs(struct task_struct *t); -static void print_cpu_stall_info_begin(void); -static void print_cpu_stall_info(int cpu); -static void print_cpu_stall_info_end(void); static void zero_cpu_stall_ticks(struct rcu_data *rdp); static bool rcu_nocb_cpu_needs_barrier(int cpu); static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp); @@ -445,3 +440,10 @@ static void rcu_bind_gp_kthread(void); static bool rcu_nohz_full_cpu(void); static void rcu_dynticks_task_enter(void); static void rcu_dynticks_task_exit(void); + +/* Forward declarations for tree_stall.h */ +static void record_gp_stall_check_time(void); +static void rcu_iw_handler(struct irq_work *iwp); +static void check_cpu_stall(struct rcu_data *rdp); +static void rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp, + const unsigned long gpssdelay); diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 4c2a0189e748..9c990df880d1 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -10,6 +10,7 @@ #include static void rcu_exp_handler(void *unused); +static int rcu_print_task_exp_stall(struct rcu_node *rnp); /* * Record the start of an expedited grace period. @@ -633,7 +634,7 @@ static void rcu_exp_handler(void *unused) raw_spin_lock_irqsave_rcu_node(rnp, flags); if (rnp->expmask & rdp->grpmask) { rdp->deferred_qs = true; - WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, true); + t->rcu_read_unlock_special.b.exp_hint = true; } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); return; @@ -648,7 +649,7 @@ static void rcu_exp_handler(void *unused) * * If the CPU is fully enabled (or if some buggy RCU-preempt * read-side critical section is being used from idle), just - * invoke rcu_preempt_defer_qs() to immediately report the + * invoke rcu_preempt_deferred_qs() to immediately report the * quiescent state. We cannot use rcu_read_unlock_special() * because we are in an interrupt handler, which will cause that * function to take an early exit without doing anything. @@ -670,6 +671,27 @@ static void sync_sched_exp_online_cleanup(int cpu) { } +/* + * Scan the current list of tasks blocked within RCU read-side critical + * sections, printing out the tid of each that is blocking the current + * expedited grace period. + */ +static int rcu_print_task_exp_stall(struct rcu_node *rnp) +{ + struct task_struct *t; + int ndetected = 0; + + if (!rnp->exp_tasks) + return 0; + t = list_entry(rnp->exp_tasks->prev, + struct task_struct, rcu_node_entry); + list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { + pr_cont(" P%d", t->pid); + ndetected++; + } + return ndetected; +} + #else /* #ifdef CONFIG_PREEMPT_RCU */ /* Invoked on each online non-idle CPU for expedited quiescent state. */ @@ -709,6 +731,16 @@ static void sync_sched_exp_online_cleanup(int cpu) WARN_ON_ONCE(ret); } +/* + * Because preemptible RCU does not exist, we never have to check for + * tasks blocked within RCU read-side critical sections that are + * blocking the current expedited grace period. + */ +static int rcu_print_task_exp_stall(struct rcu_node *rnp) +{ + return 0; +} + #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ /** diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 97dba50f6fb2..1102765f91fd 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -285,7 +285,7 @@ static void rcu_qs(void) TPS("cpuqs")); __this_cpu_write(rcu_data.cpu_no_qs.b.norm, false); barrier(); /* Coordinate with rcu_flavor_sched_clock_irq(). */ - current->rcu_read_unlock_special.b.need_qs = false; + WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, false); } } @@ -642,100 +642,6 @@ static void rcu_read_unlock_special(struct task_struct *t) rcu_preempt_deferred_qs_irqrestore(t, flags); } -/* - * Dump detailed information for all tasks blocking the current RCU - * grace period on the specified rcu_node structure. - */ -static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) -{ - unsigned long flags; - struct task_struct *t; - - raw_spin_lock_irqsave_rcu_node(rnp, flags); - if (!rcu_preempt_blocked_readers_cgp(rnp)) { - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - return; - } - t = list_entry(rnp->gp_tasks->prev, - struct task_struct, rcu_node_entry); - list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { - /* - * We could be printing a lot while holding a spinlock. - * Avoid triggering hard lockup. - */ - touch_nmi_watchdog(); - sched_show_task(t); - } - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); -} - -/* - * Dump detailed information for all tasks blocking the current RCU - * grace period. - */ -static void rcu_print_detail_task_stall(void) -{ - struct rcu_node *rnp = rcu_get_root(); - - rcu_print_detail_task_stall_rnp(rnp); - rcu_for_each_leaf_node(rnp) - rcu_print_detail_task_stall_rnp(rnp); -} - -static void rcu_print_task_stall_begin(struct rcu_node *rnp) -{ - pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):", - rnp->level, rnp->grplo, rnp->grphi); -} - -static void rcu_print_task_stall_end(void) -{ - pr_cont("\n"); -} - -/* - * Scan the current list of tasks blocked within RCU read-side critical - * sections, printing out the tid of each. - */ -static int rcu_print_task_stall(struct rcu_node *rnp) -{ - struct task_struct *t; - int ndetected = 0; - - if (!rcu_preempt_blocked_readers_cgp(rnp)) - return 0; - rcu_print_task_stall_begin(rnp); - t = list_entry(rnp->gp_tasks->prev, - struct task_struct, rcu_node_entry); - list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { - pr_cont(" P%d", t->pid); - ndetected++; - } - rcu_print_task_stall_end(); - return ndetected; -} - -/* - * Scan the current list of tasks blocked within RCU read-side critical - * sections, printing out the tid of each that is blocking the current - * expedited grace period. - */ -static int rcu_print_task_exp_stall(struct rcu_node *rnp) -{ - struct task_struct *t; - int ndetected = 0; - - if (!rnp->exp_tasks) - return 0; - t = list_entry(rnp->exp_tasks->prev, - struct task_struct, rcu_node_entry); - list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { - pr_cont(" P%d", t->pid); - ndetected++; - } - return ndetected; -} - /* * Check that the list of blocked tasks for the newly completed grace * period is in fact empty. It is a serious bug to complete a grace @@ -804,19 +710,25 @@ static void rcu_flavor_sched_clock_irq(int user) /* * Check for a task exiting while in a preemptible-RCU read-side - * critical section, clean up if so. No need to issue warnings, - * as debug_check_no_locks_held() already does this if lockdep - * is enabled. + * critical section, clean up if so. No need to issue warnings, as + * debug_check_no_locks_held() already does this if lockdep is enabled. + * Besides, if this function does anything other than just immediately + * return, there was a bug of some sort. Spewing warnings from this + * function is like as not to simply obscure important prior warnings. */ void exit_rcu(void) { struct task_struct *t = current; - if (likely(list_empty(¤t->rcu_node_entry))) + if (unlikely(!list_empty(¤t->rcu_node_entry))) { + t->rcu_read_lock_nesting = 1; + barrier(); + WRITE_ONCE(t->rcu_read_unlock_special.b.blocked, true); + } else if (unlikely(t->rcu_read_lock_nesting)) { + t->rcu_read_lock_nesting = 1; + } else { return; - t->rcu_read_lock_nesting = 1; - barrier(); - t->rcu_read_unlock_special.b.blocked = true; + } __rcu_read_unlock(); rcu_preempt_deferred_qs(current); } @@ -979,33 +891,6 @@ static bool rcu_preempt_need_deferred_qs(struct task_struct *t) } static void rcu_preempt_deferred_qs(struct task_struct *t) { } -/* - * Because preemptible RCU does not exist, we never have to check for - * tasks blocked within RCU read-side critical sections. - */ -static void rcu_print_detail_task_stall(void) -{ -} - -/* - * Because preemptible RCU does not exist, we never have to check for - * tasks blocked within RCU read-side critical sections. - */ -static int rcu_print_task_stall(struct rcu_node *rnp) -{ - return 0; -} - -/* - * Because preemptible RCU does not exist, we never have to check for - * tasks blocked within RCU read-side critical sections that are - * blocking the current expedited grace period. - */ -static int rcu_print_task_exp_stall(struct rcu_node *rnp) -{ - return 0; -} - /* * Because there is no preemptible RCU, there can be no readers blocked, * so there is no need to check for blocked tasks. So check only for @@ -1185,8 +1070,6 @@ static int rcu_boost_kthread(void *arg) static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) __releases(rnp->lock) { - struct task_struct *t; - raw_lockdep_assert_held_rcu_node(rnp); if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -1200,9 +1083,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) if (rnp->exp_tasks == NULL) rnp->boost_tasks = rnp->gp_tasks; raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - t = rnp->boost_kthread_task; - if (t) - rcu_wake_cond(t, rnp->boost_kthread_status); + rcu_wake_cond(rnp->boost_kthread_task, + rnp->boost_kthread_status); } else { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } @@ -1649,98 +1531,6 @@ static void rcu_cleanup_after_idle(void) #endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */ -#ifdef CONFIG_RCU_FAST_NO_HZ - -static void print_cpu_stall_fast_no_hz(char *cp, int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - - sprintf(cp, "last_accelerate: %04lx/%04lx, Nonlazy posted: %c%c%c", - rdp->last_accelerate & 0xffff, jiffies & 0xffff, - ".l"[rdp->all_lazy], - ".L"[!rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)], - ".D"[!rdp->tick_nohz_enabled_snap]); -} - -#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */ - -static void print_cpu_stall_fast_no_hz(char *cp, int cpu) -{ - *cp = '\0'; -} - -#endif /* #else #ifdef CONFIG_RCU_FAST_NO_HZ */ - -/* Initiate the stall-info list. */ -static void print_cpu_stall_info_begin(void) -{ - pr_cont("\n"); -} - -/* - * Print out diagnostic information for the specified stalled CPU. - * - * If the specified CPU is aware of the current RCU grace period, then - * print the number of scheduling clock interrupts the CPU has taken - * during the time that it has been aware. Otherwise, print the number - * of RCU grace periods that this CPU is ignorant of, for example, "1" - * if the CPU was aware of the previous grace period. - * - * Also print out idle and (if CONFIG_RCU_FAST_NO_HZ) idle-entry info. - */ -static void print_cpu_stall_info(int cpu) -{ - unsigned long delta; - char fast_no_hz[72]; - struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); - char *ticks_title; - unsigned long ticks_value; - - /* - * We could be printing a lot while holding a spinlock. Avoid - * triggering hard lockup. - */ - touch_nmi_watchdog(); - - ticks_value = rcu_seq_ctr(rcu_state.gp_seq - rdp->gp_seq); - if (ticks_value) { - ticks_title = "GPs behind"; - } else { - ticks_title = "ticks this GP"; - ticks_value = rdp->ticks_this_gp; - } - print_cpu_stall_fast_no_hz(fast_no_hz, cpu); - delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq); - pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld %s\n", - cpu, - "O."[!!cpu_online(cpu)], - "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)], - "N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)], - !IS_ENABLED(CONFIG_IRQ_WORK) ? '?' : - rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : - "!."[!delta], - ticks_value, ticks_title, - rcu_dynticks_snap(rdp) & 0xfff, - rdp->dynticks_nesting, rdp->dynticks_nmi_nesting, - rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), - READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, - fast_no_hz); -} - -/* Terminate the stall-info list. */ -static void print_cpu_stall_info_end(void) -{ - pr_err("\t"); -} - -/* Zero ->ticks_this_gp and snapshot the number of RCU softirq handlers. */ -static void zero_cpu_stall_ticks(struct rcu_data *rdp) -{ - rdp->ticks_this_gp = 0; - rdp->softirq_snap = kstat_softirqs_cpu(RCU_SOFTIRQ, smp_processor_id()); - WRITE_ONCE(rdp->last_fqs_resched, jiffies); -} - #ifdef CONFIG_RCU_NOCB_CPU /* @@ -1766,11 +1556,22 @@ static void zero_cpu_stall_ticks(struct rcu_data *rdp) */ -/* Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. */ +/* + * Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. + * The string after the "rcu_nocbs=" is either "all" for all CPUs, or a + * comma-separated list of CPUs and/or CPU ranges. If an invalid list is + * given, a warning is emitted and all CPUs are offloaded. + */ static int __init rcu_nocb_setup(char *str) { alloc_bootmem_cpumask_var(&rcu_nocb_mask); - cpulist_parse(str, rcu_nocb_mask); + if (!strcasecmp(str, "all")) + cpumask_setall(rcu_nocb_mask); + else + if (cpulist_parse(str, rcu_nocb_mask)) { + pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n"); + cpumask_setall(rcu_nocb_mask); + } return 1; } __setup("rcu_nocbs=", rcu_nocb_setup); diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h new file mode 100644 index 000000000000..f65a73a97323 --- /dev/null +++ b/kernel/rcu/tree_stall.h @@ -0,0 +1,709 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * RCU CPU stall warnings for normal RCU grace periods + * + * Copyright IBM Corporation, 2019 + * + * Author: Paul E. McKenney + */ + +////////////////////////////////////////////////////////////////////////////// +// +// Controlling CPU stall warnings, including delay calculation. + +/* panic() on RCU Stall sysctl. */ +int sysctl_panic_on_rcu_stall __read_mostly; + +#ifdef CONFIG_PROVE_RCU +#define RCU_STALL_DELAY_DELTA (5 * HZ) +#else +#define RCU_STALL_DELAY_DELTA 0 +#endif + +/* Limit-check stall timeouts specified at boottime and runtime. */ +int rcu_jiffies_till_stall_check(void) +{ + int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout); + + /* + * Limit check must be consistent with the Kconfig limits + * for CONFIG_RCU_CPU_STALL_TIMEOUT. + */ + if (till_stall_check < 3) { + WRITE_ONCE(rcu_cpu_stall_timeout, 3); + till_stall_check = 3; + } else if (till_stall_check > 300) { + WRITE_ONCE(rcu_cpu_stall_timeout, 300); + till_stall_check = 300; + } + return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; +} +EXPORT_SYMBOL_GPL(rcu_jiffies_till_stall_check); + +/* Don't do RCU CPU stall warnings during long sysrq printouts. */ +void rcu_sysrq_start(void) +{ + if (!rcu_cpu_stall_suppress) + rcu_cpu_stall_suppress = 2; +} + +void rcu_sysrq_end(void) +{ + if (rcu_cpu_stall_suppress == 2) + rcu_cpu_stall_suppress = 0; +} + +/* Don't print RCU CPU stall warnings during a kernel panic. */ +static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) +{ + rcu_cpu_stall_suppress = 1; + return NOTIFY_DONE; +} + +static struct notifier_block rcu_panic_block = { + .notifier_call = rcu_panic, +}; + +static int __init check_cpu_stall_init(void) +{ + atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); + return 0; +} +early_initcall(check_cpu_stall_init); + +/* If so specified via sysctl, panic, yielding cleaner stall-warning output. */ +static void panic_on_rcu_stall(void) +{ + if (sysctl_panic_on_rcu_stall) + panic("RCU Stall\n"); +} + +/** + * rcu_cpu_stall_reset - prevent further stall warnings in current grace period + * + * Set the stall-warning timeout way off into the future, thus preventing + * any RCU CPU stall-warning messages from appearing in the current set of + * RCU grace periods. + * + * The caller must disable hard irqs. + */ +void rcu_cpu_stall_reset(void) +{ + WRITE_ONCE(rcu_state.jiffies_stall, jiffies + ULONG_MAX / 2); +} + +////////////////////////////////////////////////////////////////////////////// +// +// Interaction with RCU grace periods + +/* Start of new grace period, so record stall time (and forcing times). */ +static void record_gp_stall_check_time(void) +{ + unsigned long j = jiffies; + unsigned long j1; + + rcu_state.gp_start = j; + j1 = rcu_jiffies_till_stall_check(); + /* Record ->gp_start before ->jiffies_stall. */ + smp_store_release(&rcu_state.jiffies_stall, j + j1); /* ^^^ */ + rcu_state.jiffies_resched = j + j1 / 2; + rcu_state.n_force_qs_gpstart = READ_ONCE(rcu_state.n_force_qs); +} + +/* Zero ->ticks_this_gp and snapshot the number of RCU softirq handlers. */ +static void zero_cpu_stall_ticks(struct rcu_data *rdp) +{ + rdp->ticks_this_gp = 0; + rdp->softirq_snap = kstat_softirqs_cpu(RCU_SOFTIRQ, smp_processor_id()); + WRITE_ONCE(rdp->last_fqs_resched, jiffies); +} + +/* + * If too much time has passed in the current grace period, and if + * so configured, go kick the relevant kthreads. + */ +static void rcu_stall_kick_kthreads(void) +{ + unsigned long j; + + if (!rcu_kick_kthreads) + return; + j = READ_ONCE(rcu_state.jiffies_kick_kthreads); + if (time_after(jiffies, j) && rcu_state.gp_kthread && + (rcu_gp_in_progress() || READ_ONCE(rcu_state.gp_flags))) { + WARN_ONCE(1, "Kicking %s grace-period kthread\n", + rcu_state.name); + rcu_ftrace_dump(DUMP_ALL); + wake_up_process(rcu_state.gp_kthread); + WRITE_ONCE(rcu_state.jiffies_kick_kthreads, j + HZ); + } +} + +/* + * Handler for the irq_work request posted about halfway into the RCU CPU + * stall timeout, and used to detect excessive irq disabling. Set state + * appropriately, but just complain if there is unexpected state on entry. + */ +static void rcu_iw_handler(struct irq_work *iwp) +{ + struct rcu_data *rdp; + struct rcu_node *rnp; + + rdp = container_of(iwp, struct rcu_data, rcu_iw); + rnp = rdp->mynode; + raw_spin_lock_rcu_node(rnp); + if (!WARN_ON_ONCE(!rdp->rcu_iw_pending)) { + rdp->rcu_iw_gp_seq = rnp->gp_seq; + rdp->rcu_iw_pending = false; + } + raw_spin_unlock_rcu_node(rnp); +} + +////////////////////////////////////////////////////////////////////////////// +// +// Printing RCU CPU stall warnings + +#ifdef CONFIG_PREEMPT + +/* + * Dump detailed information for all tasks blocking the current RCU + * grace period on the specified rcu_node structure. + */ +static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) +{ + unsigned long flags; + struct task_struct *t; + + raw_spin_lock_irqsave_rcu_node(rnp, flags); + if (!rcu_preempt_blocked_readers_cgp(rnp)) { + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + return; + } + t = list_entry(rnp->gp_tasks->prev, + struct task_struct, rcu_node_entry); + list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { + /* + * We could be printing a lot while holding a spinlock. + * Avoid triggering hard lockup. + */ + touch_nmi_watchdog(); + sched_show_task(t); + } + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); +} + +/* + * Scan the current list of tasks blocked within RCU read-side critical + * sections, printing out the tid of each. + */ +static int rcu_print_task_stall(struct rcu_node *rnp) +{ + struct task_struct *t; + int ndetected = 0; + + if (!rcu_preempt_blocked_readers_cgp(rnp)) + return 0; + pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):", + rnp->level, rnp->grplo, rnp->grphi); + t = list_entry(rnp->gp_tasks->prev, + struct task_struct, rcu_node_entry); + list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { + pr_cont(" P%d", t->pid); + ndetected++; + } + pr_cont("\n"); + return ndetected; +} + +#else /* #ifdef CONFIG_PREEMPT */ + +/* + * Because preemptible RCU does not exist, we never have to check for + * tasks blocked within RCU read-side critical sections. + */ +static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) +{ +} + +/* + * Because preemptible RCU does not exist, we never have to check for + * tasks blocked within RCU read-side critical sections. + */ +static int rcu_print_task_stall(struct rcu_node *rnp) +{ + return 0; +} +#endif /* #else #ifdef CONFIG_PREEMPT */ + +/* + * Dump stacks of all tasks running on stalled CPUs. First try using + * NMIs, but fall back to manual remote stack tracing on architectures + * that don't support NMI-based stack dumps. The NMI-triggered stack + * traces are more accurate because they are printed by the target CPU. + */ +static void rcu_dump_cpu_stacks(void) +{ + int cpu; + unsigned long flags; + struct rcu_node *rnp; + + rcu_for_each_leaf_node(rnp) { + raw_spin_lock_irqsave_rcu_node(rnp, flags); + for_each_leaf_node_possible_cpu(rnp, cpu) + if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) + if (!trigger_single_cpu_backtrace(cpu)) + dump_cpu_task(cpu); + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + } +} + +#ifdef CONFIG_RCU_FAST_NO_HZ + +static void print_cpu_stall_fast_no_hz(char *cp, int cpu) +{ + struct rcu_data *rdp = &per_cpu(rcu_data, cpu); + + sprintf(cp, "last_accelerate: %04lx/%04lx, Nonlazy posted: %c%c%c", + rdp->last_accelerate & 0xffff, jiffies & 0xffff, + ".l"[rdp->all_lazy], + ".L"[!rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)], + ".D"[!!rdp->tick_nohz_enabled_snap]); +} + +#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */ + +static void print_cpu_stall_fast_no_hz(char *cp, int cpu) +{ + *cp = '\0'; +} + +#endif /* #else #ifdef CONFIG_RCU_FAST_NO_HZ */ + +/* + * Print out diagnostic information for the specified stalled CPU. + * + * If the specified CPU is aware of the current RCU grace period, then + * print the number of scheduling clock interrupts the CPU has taken + * during the time that it has been aware. Otherwise, print the number + * of RCU grace periods that this CPU is ignorant of, for example, "1" + * if the CPU was aware of the previous grace period. + * + * Also print out idle and (if CONFIG_RCU_FAST_NO_HZ) idle-entry info. + */ +static void print_cpu_stall_info(int cpu) +{ + unsigned long delta; + char fast_no_hz[72]; + struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); + char *ticks_title; + unsigned long ticks_value; + + /* + * We could be printing a lot while holding a spinlock. Avoid + * triggering hard lockup. + */ + touch_nmi_watchdog(); + + ticks_value = rcu_seq_ctr(rcu_state.gp_seq - rdp->gp_seq); + if (ticks_value) { + ticks_title = "GPs behind"; + } else { + ticks_title = "ticks this GP"; + ticks_value = rdp->ticks_this_gp; + } + print_cpu_stall_fast_no_hz(fast_no_hz, cpu); + delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq); + pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld %s\n", + cpu, + "O."[!!cpu_online(cpu)], + "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)], + "N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)], + !IS_ENABLED(CONFIG_IRQ_WORK) ? '?' : + rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : + "!."[!delta], + ticks_value, ticks_title, + rcu_dynticks_snap(rdp) & 0xfff, + rdp->dynticks_nesting, rdp->dynticks_nmi_nesting, + rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), + READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, + fast_no_hz); +} + +/* Complain about starvation of grace-period kthread. */ +static void rcu_check_gp_kthread_starvation(void) +{ + struct task_struct *gpk = rcu_state.gp_kthread; + unsigned long j; + + j = jiffies - READ_ONCE(rcu_state.gp_activity); + if (j > 2 * HZ) { + pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#lx ->cpu=%d\n", + rcu_state.name, j, + (long)rcu_seq_current(&rcu_state.gp_seq), + READ_ONCE(rcu_state.gp_flags), + gp_state_getname(rcu_state.gp_state), rcu_state.gp_state, + gpk ? gpk->state : ~0, gpk ? task_cpu(gpk) : -1); + if (gpk) { + pr_err("RCU grace-period kthread stack dump:\n"); + sched_show_task(gpk); + wake_up_process(gpk); + } + } +} + +static void print_other_cpu_stall(unsigned long gp_seq) +{ + int cpu; + unsigned long flags; + unsigned long gpa; + unsigned long j; + int ndetected = 0; + struct rcu_node *rnp; + long totqlen = 0; + + /* Kick and suppress, if so configured. */ + rcu_stall_kick_kthreads(); + if (rcu_cpu_stall_suppress) + return; + + /* + * OK, time to rat on our buddy... + * See Documentation/RCU/stallwarn.txt for info on how to debug + * RCU CPU stall warnings. + */ + pr_err("INFO: %s detected stalls on CPUs/tasks:\n", rcu_state.name); + rcu_for_each_leaf_node(rnp) { + raw_spin_lock_irqsave_rcu_node(rnp, flags); + ndetected += rcu_print_task_stall(rnp); + if (rnp->qsmask != 0) { + for_each_leaf_node_possible_cpu(rnp, cpu) + if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) { + print_cpu_stall_info(cpu); + ndetected++; + } + } + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + } + + for_each_possible_cpu(cpu) + totqlen += rcu_get_n_cbs_cpu(cpu); + pr_cont("\t(detected by %d, t=%ld jiffies, g=%ld, q=%lu)\n", + smp_processor_id(), (long)(jiffies - rcu_state.gp_start), + (long)rcu_seq_current(&rcu_state.gp_seq), totqlen); + if (ndetected) { + rcu_dump_cpu_stacks(); + + /* Complain about tasks blocking the grace period. */ + rcu_for_each_leaf_node(rnp) + rcu_print_detail_task_stall_rnp(rnp); + } else { + if (rcu_seq_current(&rcu_state.gp_seq) != gp_seq) { + pr_err("INFO: Stall ended before state dump start\n"); + } else { + j = jiffies; + gpa = READ_ONCE(rcu_state.gp_activity); + pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n", + rcu_state.name, j - gpa, j, gpa, + READ_ONCE(jiffies_till_next_fqs), + rcu_get_root()->qsmask); + /* In this case, the current CPU might be at fault. */ + sched_show_task(current); + } + } + /* Rewrite if needed in case of slow consoles. */ + if (ULONG_CMP_GE(jiffies, READ_ONCE(rcu_state.jiffies_stall))) + WRITE_ONCE(rcu_state.jiffies_stall, + jiffies + 3 * rcu_jiffies_till_stall_check() + 3); + + rcu_check_gp_kthread_starvation(); + + panic_on_rcu_stall(); + + rcu_force_quiescent_state(); /* Kick them all. */ +} + +static void print_cpu_stall(void) +{ + int cpu; + unsigned long flags; + struct rcu_data *rdp = this_cpu_ptr(&rcu_data); + struct rcu_node *rnp = rcu_get_root(); + long totqlen = 0; + + /* Kick and suppress, if so configured. */ + rcu_stall_kick_kthreads(); + if (rcu_cpu_stall_suppress) + return; + + /* + * OK, time to rat on ourselves... + * See Documentation/RCU/stallwarn.txt for info on how to debug + * RCU CPU stall warnings. + */ + pr_err("INFO: %s self-detected stall on CPU\n", rcu_state.name); + raw_spin_lock_irqsave_rcu_node(rdp->mynode, flags); + print_cpu_stall_info(smp_processor_id()); + raw_spin_unlock_irqrestore_rcu_node(rdp->mynode, flags); + for_each_possible_cpu(cpu) + totqlen += rcu_get_n_cbs_cpu(cpu); + pr_cont("\t(t=%lu jiffies g=%ld q=%lu)\n", + jiffies - rcu_state.gp_start, + (long)rcu_seq_current(&rcu_state.gp_seq), totqlen); + + rcu_check_gp_kthread_starvation(); + + rcu_dump_cpu_stacks(); + + raw_spin_lock_irqsave_rcu_node(rnp, flags); + /* Rewrite if needed in case of slow consoles. */ + if (ULONG_CMP_GE(jiffies, READ_ONCE(rcu_state.jiffies_stall))) + WRITE_ONCE(rcu_state.jiffies_stall, + jiffies + 3 * rcu_jiffies_till_stall_check() + 3); + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + + panic_on_rcu_stall(); + + /* + * Attempt to revive the RCU machinery by forcing a context switch. + * + * A context switch would normally allow the RCU state machine to make + * progress and it could be we're stuck in kernel space without context + * switches for an entirely unreasonable amount of time. + */ + set_tsk_need_resched(current); + set_preempt_need_resched(); +} + +static void check_cpu_stall(struct rcu_data *rdp) +{ + unsigned long gs1; + unsigned long gs2; + unsigned long gps; + unsigned long j; + unsigned long jn; + unsigned long js; + struct rcu_node *rnp; + + if ((rcu_cpu_stall_suppress && !rcu_kick_kthreads) || + !rcu_gp_in_progress()) + return; + rcu_stall_kick_kthreads(); + j = jiffies; + + /* + * Lots of memory barriers to reject false positives. + * + * The idea is to pick up rcu_state.gp_seq, then + * rcu_state.jiffies_stall, then rcu_state.gp_start, and finally + * another copy of rcu_state.gp_seq. These values are updated in + * the opposite order with memory barriers (or equivalent) during + * grace-period initialization and cleanup. Now, a false positive + * can occur if we get an new value of rcu_state.gp_start and a old + * value of rcu_state.jiffies_stall. But given the memory barriers, + * the only way that this can happen is if one grace period ends + * and another starts between these two fetches. This is detected + * by comparing the second fetch of rcu_state.gp_seq with the + * previous fetch from rcu_state.gp_seq. + * + * Given this check, comparisons of jiffies, rcu_state.jiffies_stall, + * and rcu_state.gp_start suffice to forestall false positives. + */ + gs1 = READ_ONCE(rcu_state.gp_seq); + smp_rmb(); /* Pick up ->gp_seq first... */ + js = READ_ONCE(rcu_state.jiffies_stall); + smp_rmb(); /* ...then ->jiffies_stall before the rest... */ + gps = READ_ONCE(rcu_state.gp_start); + smp_rmb(); /* ...and finally ->gp_start before ->gp_seq again. */ + gs2 = READ_ONCE(rcu_state.gp_seq); + if (gs1 != gs2 || + ULONG_CMP_LT(j, js) || + ULONG_CMP_GE(gps, js)) + return; /* No stall or GP completed since entering function. */ + rnp = rdp->mynode; + jn = jiffies + 3 * rcu_jiffies_till_stall_check() + 3; + if (rcu_gp_in_progress() && + (READ_ONCE(rnp->qsmask) & rdp->grpmask) && + cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) { + + /* We haven't checked in, so go dump stack. */ + print_cpu_stall(); + + } else if (rcu_gp_in_progress() && + ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY) && + cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) { + + /* They had a few time units to dump stack, so complain. */ + print_other_cpu_stall(gs2); + } +} + +////////////////////////////////////////////////////////////////////////////// +// +// RCU forward-progress mechanisms, including of callback invocation. + + +/* + * Show the state of the grace-period kthreads. + */ +void show_rcu_gp_kthreads(void) +{ + int cpu; + unsigned long j; + unsigned long ja; + unsigned long jr; + unsigned long jw; + struct rcu_data *rdp; + struct rcu_node *rnp; + + j = jiffies; + ja = j - READ_ONCE(rcu_state.gp_activity); + jr = j - READ_ONCE(rcu_state.gp_req_activity); + jw = j - READ_ONCE(rcu_state.gp_wake_time); + pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n", + rcu_state.name, gp_state_getname(rcu_state.gp_state), + rcu_state.gp_state, + rcu_state.gp_kthread ? rcu_state.gp_kthread->state : 0x1ffffL, + ja, jr, jw, (long)READ_ONCE(rcu_state.gp_wake_seq), + (long)READ_ONCE(rcu_state.gp_seq), + (long)READ_ONCE(rcu_get_root()->gp_seq_needed), + READ_ONCE(rcu_state.gp_flags)); + rcu_for_each_node_breadth_first(rnp) { + if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed)) + continue; + pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld\n", + rnp->grplo, rnp->grphi, (long)rnp->gp_seq, + (long)rnp->gp_seq_needed); + if (!rcu_is_leaf_node(rnp)) + continue; + for_each_leaf_node_possible_cpu(rnp, cpu) { + rdp = per_cpu_ptr(&rcu_data, cpu); + if (rdp->gpwrap || + ULONG_CMP_GE(rcu_state.gp_seq, + rdp->gp_seq_needed)) + continue; + pr_info("\tcpu %d ->gp_seq_needed %ld\n", + cpu, (long)rdp->gp_seq_needed); + } + } + /* sched_show_task(rcu_state.gp_kthread); */ +} +EXPORT_SYMBOL_GPL(show_rcu_gp_kthreads); + +/* + * This function checks for grace-period requests that fail to motivate + * RCU to come out of its idle mode. + */ +static void rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp, + const unsigned long gpssdelay) +{ + unsigned long flags; + unsigned long j; + struct rcu_node *rnp_root = rcu_get_root(); + static atomic_t warned = ATOMIC_INIT(0); + + if (!IS_ENABLED(CONFIG_PROVE_RCU) || rcu_gp_in_progress() || + ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed)) + return; + j = jiffies; /* Expensive access, and in common case don't get here. */ + if (time_before(j, READ_ONCE(rcu_state.gp_req_activity) + gpssdelay) || + time_before(j, READ_ONCE(rcu_state.gp_activity) + gpssdelay) || + atomic_read(&warned)) + return; + + raw_spin_lock_irqsave_rcu_node(rnp, flags); + j = jiffies; + if (rcu_gp_in_progress() || + ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed) || + time_before(j, READ_ONCE(rcu_state.gp_req_activity) + gpssdelay) || + time_before(j, READ_ONCE(rcu_state.gp_activity) + gpssdelay) || + atomic_read(&warned)) { + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + return; + } + /* Hold onto the leaf lock to make others see warned==1. */ + + if (rnp_root != rnp) + raw_spin_lock_rcu_node(rnp_root); /* irqs already disabled. */ + j = jiffies; + if (rcu_gp_in_progress() || + ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed) || + time_before(j, rcu_state.gp_req_activity + gpssdelay) || + time_before(j, rcu_state.gp_activity + gpssdelay) || + atomic_xchg(&warned, 1)) { + raw_spin_unlock_rcu_node(rnp_root); /* irqs remain disabled. */ + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + return; + } + WARN_ON(1); + if (rnp_root != rnp) + raw_spin_unlock_rcu_node(rnp_root); + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + show_rcu_gp_kthreads(); +} + +/* + * Do a forward-progress check for rcutorture. This is normally invoked + * due to an OOM event. The argument "j" gives the time period during + * which rcutorture would like progress to have been made. + */ +void rcu_fwd_progress_check(unsigned long j) +{ + unsigned long cbs; + int cpu; + unsigned long max_cbs = 0; + int max_cpu = -1; + struct rcu_data *rdp; + + if (rcu_gp_in_progress()) { + pr_info("%s: GP age %lu jiffies\n", + __func__, jiffies - rcu_state.gp_start); + show_rcu_gp_kthreads(); + } else { + pr_info("%s: Last GP end %lu jiffies ago\n", + __func__, jiffies - rcu_state.gp_end); + preempt_disable(); + rdp = this_cpu_ptr(&rcu_data); + rcu_check_gp_start_stall(rdp->mynode, rdp, j); + preempt_enable(); + } + for_each_possible_cpu(cpu) { + cbs = rcu_get_n_cbs_cpu(cpu); + if (!cbs) + continue; + if (max_cpu < 0) + pr_info("%s: callbacks", __func__); + pr_cont(" %d: %lu", cpu, cbs); + if (cbs <= max_cbs) + continue; + max_cbs = cbs; + max_cpu = cpu; + } + if (max_cpu >= 0) + pr_cont("\n"); +} +EXPORT_SYMBOL_GPL(rcu_fwd_progress_check); + +/* Commandeer a sysrq key to dump RCU's tree. */ +static bool sysrq_rcu; +module_param(sysrq_rcu, bool, 0444); + +/* Dump grace-period-request information due to commandeered sysrq. */ +static void sysrq_show_rcu(int key) +{ + show_rcu_gp_kthreads(); +} + +static struct sysrq_key_op sysrq_rcudump_op = { + .handler = sysrq_show_rcu, + .help_msg = "show-rcu(y)", + .action_msg = "Show RCU tree", + .enable_mask = SYSRQ_ENABLE_DUMP, +}; + +static int __init rcu_sysrq_init(void) +{ + if (sysrq_rcu) + return register_sysrq_key('y', &sysrq_rcudump_op); + return 0; +} +early_initcall(rcu_sysrq_init); diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index cbaa976c5945..c3bf44ba42e5 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -424,68 +424,11 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); #endif #ifdef CONFIG_RCU_STALL_COMMON - -#ifdef CONFIG_PROVE_RCU -#define RCU_STALL_DELAY_DELTA (5 * HZ) -#else -#define RCU_STALL_DELAY_DELTA 0 -#endif - int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); -static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; - module_param(rcu_cpu_stall_suppress, int, 0644); +int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; module_param(rcu_cpu_stall_timeout, int, 0644); - -int rcu_jiffies_till_stall_check(void) -{ - int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout); - - /* - * Limit check must be consistent with the Kconfig limits - * for CONFIG_RCU_CPU_STALL_TIMEOUT. - */ - if (till_stall_check < 3) { - WRITE_ONCE(rcu_cpu_stall_timeout, 3); - till_stall_check = 3; - } else if (till_stall_check > 300) { - WRITE_ONCE(rcu_cpu_stall_timeout, 300); - till_stall_check = 300; - } - return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; -} -EXPORT_SYMBOL_GPL(rcu_jiffies_till_stall_check); - -void rcu_sysrq_start(void) -{ - if (!rcu_cpu_stall_suppress) - rcu_cpu_stall_suppress = 2; -} - -void rcu_sysrq_end(void) -{ - if (rcu_cpu_stall_suppress == 2) - rcu_cpu_stall_suppress = 0; -} - -static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) -{ - rcu_cpu_stall_suppress = 1; - return NOTIFY_DONE; -} - -static struct notifier_block rcu_panic_block = { - .notifier_call = rcu_panic, -}; - -static int __init check_cpu_stall_init(void) -{ - atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); - return 0; -} -early_initcall(check_cpu_stall_init); - #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ #ifdef CONFIG_TASKS_RCU diff --git a/kernel/torture.c b/kernel/torture.c index 8faa1a9aaeb9..17b2be9bde12 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -88,6 +88,8 @@ bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes, if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu)) return false; + if (num_online_cpus() <= 1) + return false; /* Can't offline the last CPU. */ if (verbose > 1) pr_alert("%s" TORTURE_FLAG diff --git a/tools/testing/selftests/rcutorture/bin/configNR_CPUS.sh b/tools/testing/selftests/rcutorture/bin/configNR_CPUS.sh index 43540f1828cc..2deea2169fc2 100755 --- a/tools/testing/selftests/rcutorture/bin/configNR_CPUS.sh +++ b/tools/testing/selftests/rcutorture/bin/configNR_CPUS.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Extract the number of CPUs expected from the specified Kconfig-file # fragment by checking CONFIG_SMP and CONFIG_NR_CPUS. If the specified @@ -7,23 +8,9 @@ # # Usage: configNR_CPUS.sh config-frag # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2013 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney cf=$1 if test ! -r $cf diff --git a/tools/testing/selftests/rcutorture/bin/config_override.sh b/tools/testing/selftests/rcutorture/bin/config_override.sh index ef7fcbac3d42..90016c359e83 100755 --- a/tools/testing/selftests/rcutorture/bin/config_override.sh +++ b/tools/testing/selftests/rcutorture/bin/config_override.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # config_override.sh base override # @@ -6,23 +7,9 @@ # that conflict with any in override, concatenating what remains and # sending the result to standard output. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2017 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney base=$1 if test -r $base diff --git a/tools/testing/selftests/rcutorture/bin/configcheck.sh b/tools/testing/selftests/rcutorture/bin/configcheck.sh index 197deece7c7c..31584cee84d7 100755 --- a/tools/testing/selftests/rcutorture/bin/configcheck.sh +++ b/tools/testing/selftests/rcutorture/bin/configcheck.sh @@ -1,23 +1,11 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ +# # Usage: configcheck.sh .config .config-template # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney T=${TMPDIR-/tmp}/abat-chk-config.sh.$$ trap 'rm -rf $T' 0 @@ -26,6 +14,7 @@ mkdir $T cat $1 > $T/.config cat $2 | sed -e 's/\(.*\)=n/# \1 is not set/' -e 's/^#CHECK#//' | +grep -v '^CONFIG_INITRAMFS_SOURCE' | awk ' { print "if grep -q \"" $0 "\" < '"$T/.config"'"; diff --git a/tools/testing/selftests/rcutorture/bin/configinit.sh b/tools/testing/selftests/rcutorture/bin/configinit.sh index 65541c21a544..40359486b3a8 100755 --- a/tools/testing/selftests/rcutorture/bin/configinit.sh +++ b/tools/testing/selftests/rcutorture/bin/configinit.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Usage: configinit.sh config-spec-file build-output-dir results-dir # @@ -14,23 +15,9 @@ # for example, "O=/tmp/foo". If this argument is omitted, the .config # file will be generated directly in the current directory. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2013 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney T=${TMPDIR-/tmp}/configinit.sh.$$ trap 'rm -rf $T' 0 diff --git a/tools/testing/selftests/rcutorture/bin/cpus2use.sh b/tools/testing/selftests/rcutorture/bin/cpus2use.sh index bb99cde3f5f9..ff7102212703 100755 --- a/tools/testing/selftests/rcutorture/bin/cpus2use.sh +++ b/tools/testing/selftests/rcutorture/bin/cpus2use.sh @@ -1,26 +1,13 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Get an estimate of how CPU-hoggy to be. # # Usage: cpus2use.sh # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2013 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney ncpus=`grep '^processor' /proc/cpuinfo | wc -l` idlecpus=`mpstat | tail -1 | \ diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh index 65f6655026f0..6bcb8b5b2ff2 100644 --- a/tools/testing/selftests/rcutorture/bin/functions.sh +++ b/tools/testing/selftests/rcutorture/bin/functions.sh @@ -1,24 +1,11 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Shell functions for the rest of the scripts. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2013 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney # bootparam_hotplug_cpu bootparam-string # diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh index 3633828375e3..435b60933985 100755 --- a/tools/testing/selftests/rcutorture/bin/jitter.sh +++ b/tools/testing/selftests/rcutorture/bin/jitter.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Alternate sleeping and spinning on randomly selected CPUs. The purpose # of this script is to inflict random OS jitter on a concurrently running @@ -11,23 +12,9 @@ # sleepmax: Maximum microseconds to sleep, defaults to one second. # spinmax: Maximum microseconds to spin, defaults to one millisecond. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2016 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney me=$(($1 * 1000)) duration=$2 diff --git a/tools/testing/selftests/rcutorture/bin/kvm-build.sh b/tools/testing/selftests/rcutorture/bin/kvm-build.sh index 9115fcdb5617..c27a0bbb9c02 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-build.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-build.sh @@ -1,26 +1,13 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Build a kvm-ready Linux kernel from the tree in the current directory. # # Usage: kvm-build.sh config-template build-dir resdir # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney config_template=${1} if test -z "$config_template" -o ! -f "$config_template" -o ! -r "$config_template" diff --git a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh index 98f650c9bf54..8426fe1f15ee 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh @@ -1,4 +1,5 @@ #!/bin/sh +# SPDX-License-Identifier: GPL-2.0+ # # Invoke a text editor on all console.log files for all runs with diagnostics, # that is, on all such files having a console.log.diags counterpart. @@ -10,6 +11,10 @@ # # The "directory" above should end with the date/time directory, for example, # "tools/testing/selftests/rcutorture/res/2018.02.25-14:27:27". +# +# Copyright (C) IBM Corporation, 2018 +# +# Author: Paul E. McKenney rundir="${1}" if test -z "$rundir" -o ! -d "$rundir" diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-lock.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-lock.sh index 2de92f43ee8c..f3a7a5e2b89d 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-lock.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-lock.sh @@ -1,26 +1,13 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Analyze a given results directory for locktorture progress. # # Usage: kvm-recheck-lock.sh resdir # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2014 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney i="$1" if test -d "$i" -a -r "$i" diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh index 0fa8a61ccb7b..2a7f3f4756a7 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh @@ -1,26 +1,13 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Analyze a given results directory for rcutorture progress. # # Usage: kvm-recheck-rcu.sh resdir # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2014 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney i="$1" if test -d "$i" -a -r "$i" diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh index 8948f7926b21..7d3c2be66c64 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Analyze a given results directory for rcuperf performance measurements, # looking for ftrace data. Exits with 0 if data was found, analyzed, and @@ -7,23 +8,9 @@ # # Usage: kvm-recheck-rcuperf-ftrace.sh resdir # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2016 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney i="$1" . functions.sh diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh index ccebf772fa1e..db0375a57f28 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh @@ -1,26 +1,13 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Analyze a given results directory for rcuperf performance measurements. # # Usage: kvm-recheck-rcuperf.sh resdir # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2016 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney i="$1" if test -d "$i" -a -r "$i" diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh index c9bab57a77eb..2adde6aaafdb 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Given the results directories for previous KVM-based torture runs, # check the build and console output for errors. Given a directory @@ -6,23 +7,9 @@ # # Usage: kvm-recheck.sh resdir ... # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney PATH=`pwd`/tools/testing/selftests/rcutorture/bin:$PATH; export PATH . functions.sh diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh index 58ca758a5786..0eb1ec16d78a 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Run a kvm-based test of the specified tree on the specified configs. # Fully automated run and error checking, no graphics console. @@ -20,23 +21,9 @@ # # More sophisticated argument parsing is clearly needed. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney T=${TMPDIR-/tmp}/kvm-test-1-run.sh.$$ trap 'rm -rf $T' 0 diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh index 19864f1cb27a..8f1e337b9b54 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Run a series of tests under KVM. By default, this series is specified # by the relevant CFLIST file, but can be overridden by the --configs @@ -6,23 +7,9 @@ # # Usage: kvm.sh [ options ] # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney scriptname=$0 args="$*" diff --git a/tools/testing/selftests/rcutorture/bin/mkinitrd.sh b/tools/testing/selftests/rcutorture/bin/mkinitrd.sh index 83552bb007b4..6fa9bd1ddc09 100755 --- a/tools/testing/selftests/rcutorture/bin/mkinitrd.sh +++ b/tools/testing/selftests/rcutorture/bin/mkinitrd.sh @@ -1,21 +1,8 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Create an initrd directory if one does not already exist. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2013 # # Author: Connor Shu diff --git a/tools/testing/selftests/rcutorture/bin/parse-build.sh b/tools/testing/selftests/rcutorture/bin/parse-build.sh index 24fe5f822b28..0701b3bf6ade 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-build.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-build.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Check the build output from an rcutorture run for goodness. # The "file" is a pathname on the local system, and "title" is @@ -8,23 +9,9 @@ # # Usage: parse-build.sh file title # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney F=$1 title=$2 diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh index 84933f6aed77..4508373a922f 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-console.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh @@ -1,4 +1,5 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Check the console output from an rcutorture run for oopses. # The "file" is a pathname on the local system, and "title" is @@ -6,23 +7,9 @@ # # Usage: parse-console.sh file title # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2011 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney T=${TMPDIR-/tmp}/parse-console.sh.$$ file="$1" diff --git a/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh index 80eb646e1319..d3e4b2971f92 100644 --- a/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh +++ b/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh @@ -1,24 +1,11 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Kernel-version-dependent shell functions for the rest of the scripts. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2014 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney # locktorture_param_onoff bootparam-string config-file # diff --git a/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh index 7bab8246392b..effa415f9b92 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh +++ b/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh @@ -1,24 +1,11 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Kernel-version-dependent shell functions for the rest of the scripts. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2013 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney # rcutorture_param_n_barrier_cbs bootparam-string # diff --git a/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh index d36b8fd6f0fc..777d5b0c190f 100644 --- a/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh +++ b/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh @@ -1,24 +1,11 @@ #!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ # # Torture-suite-dependent shell functions for the rest of the scripts. # -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program; if not, you can access it online at -# http://www.gnu.org/licenses/gpl-2.0.html. -# # Copyright (C) IBM Corporation, 2015 # -# Authors: Paul E. McKenney +# Authors: Paul E. McKenney # per_version_boot_params bootparam-string config-file seconds #