The s_hdrwords variable was used to indicate whether a
packet was already built on a previous iteration of the
send engine. This variable assumed the protection of the
QP's RVT_S_BUSY flag, which was required since the the
QP's s_lock was dropped just prior to the packet being
queued on the one of the egress mechanisms.
Support for multiple send engine instantiations require
that the field not be used due to concurency issues.
The ps.txreq signals the "already built" without the
potential concurency issues.
Fix by getting rid of all s_hdrword usage. A wrapper
is added to test for the already built case that used to
use s_hdrwords.
What used to be stored in s_hdrwords is now in the txreq.
The PBC is not counted, but is added in the pio/sdma code
paths prior to posting the packet.
Reviewed-by: Don Hiatt <don.hiatt@intel.com>
Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The dd refcount is speculatively incremented prior to allocating
the fd memory with kzalloc(). If that kzalloc() failed the dd
refcount leaks.
Increment refcount on kzalloc success.
Fixes: e11ffbd575 ("IB/hfi1: Do not free hfi1 cdev parent structure early")
Reviewed-by: Michael J Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Alex Estrin <alex.estrin@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The pci_request_irq() interfaces always adds the IRQF_SHARED bit to
all IRQ requests.
When the kernel is built with CONFIG_DEBUG_SHIRQ config flag, if the
IRQF_SHARED bit is set, a call to the IRQ handler is made from the
__free_irq() function. This is testing a race condition between the
IRQ cleanup and an IRQ racing the cleanup. The HFI driver should be
able to handle this race, but does not.
This race can cause traces that start with this footprint:
BUG: unable to handle kernel NULL pointer dereference at (null)
Call Trace:
<hfi1 irq handler>
...
__free_irq+0x1b3/0x2d0
free_irq+0x35/0x70
pci_free_irq+0x1c/0x30
clean_up_interrupts+0x53/0xf0 [hfi1]
hfi1_start_cleanup+0x122/0x190 [hfi1]
postinit_cleanup+0x1d/0x280 [hfi1]
remove_one+0x233/0x250 [hfi1]
pci_device_remove+0x39/0xc0
Export IRQ cleanup function so it can be called from other modules.
Using the exported cleanup function:
Re-order the driver cleanup code to clean up IRQ resources before
other resources, eliminating the race.
Re-order error path for init so that the race does not occur.
Reduce severity on spurious error message for SDMA IRQs to info.
Reviewed-by: Alex Estrin <alex.estrin@intel.com>
Reviewed-by: Patel Jay P <jay.p.patel@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
We should return -ENOMEM if the allocation fails. The current code
accidentally returns success.
Fixes: bf3c5a93c5 ("RDMA/nldev: Provide global resource utilization")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The mtt_table is cleaned up during the err_unmap_cqe label, it is a
mistake to duplicate the cleanup during the later unwind labels.
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This patch mainly fix some style warings matched with the new checkpatch
requirement. The warning as follows:
WARNING: function definition argument 'struct hns_roce_cq *' should also have
an identifier name
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The double not-operator is unncessary when used in a boolean context. This
patch removes them.
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Add a jump target so that a bit of exception handling can be better reused
at the end of this function.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Devesh Sharma <devesh.sharma@broadcom.com>
Acked-by: Jonathan Toppins <jtoppins@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Omit extra messages for a memory allocation failure in this function.
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Devesh Sharma <devesh.sharma@broadcom.com>
Acked-by: Jonathan Toppins <jtoppins@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
In the function rxe_av_fill_ip_info, the parameter rxe is not used.
So it is removed.
CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
The function rxe_av_fill_ip_info always returns 0. So the function
type is changed to void.
CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Since the function rxe_av_to_attr always return 0, the function
type is changed to void.
CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
In the function rxe_av_to_attr, the parameter rxe is
not used. So it is removed.
CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
The function rxe_av_from_attr always return 0. So change the
function to void.
CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
In the function rxe_av_from_attr, the parameter rxe
is not used. So it is removed.
CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
The nldev was implemented by following devlink implementation,
including SET/DEL/NEW commands. However these commands were not
implemented and hence don't need to be exposed.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
We should return -ENOMEM if the allocation fails. (The current code
returns succees).
Fixes: 37cb11acf1 ("RDMA/bnxt_re: Add SRQ support for Broadcom adapters")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-By: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
If there is ever any error while creating srq->umem, we return that
error, we don't store it in srq->umem, so any check of srq->umem for
IS_ERR is pointless. Further, checking udata is unnecessary as
srq->umem is always either NULL or valid, without respect to udata.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
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Merge tag v4.15 of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
To resolve conflicts in:
drivers/infiniband/hw/mlx5/main.c
drivers/infiniband/hw/mlx5/qp.c
From patches merged into the -rc cycle. The conflict resolution matches
what linux-next has been carrying.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Implement RDMA nldev netlink interface to get detailed information on each
QP in the system. This includes the owning process or kernel ULP and
detailed information from the qp_attrs.
Currently only the dumpit variant is implemented.
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Expose through the netlink interface the global per-device utilization of
the supported object types.
Provide both dumpit and doit callbacks.
As an example of possible output from rdmatool for system with 5
mlx5 cards:
$ rdma res
1: mlx5_0: qp 4 cq 5 pd 3
2: mlx5_1: qp 4 cq 5 pd 3
3: mlx5_2: qp 4 cq 5 pd 3
4: mlx5_3: qp 2 cq 3 pd 2
5: mlx5_4: qp 4 cq 5 pd 3
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Track create and destroy operations of PD objects.
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Track create and destroy operations of CQ objects.
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Track create and destroy operations of QP objects.
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The RDMA subsystem has very strict set of objects to work with, but it
completely lacks tracking facilities and has no visibility of resource
utilization.
The following patch adds such infrastructure to keep track of RDMA
resources to help with debugging of user space applications. The primary
user of this infrastructure is RDMA nldev netlink (following patches), to
be exposed to userspace via rdmatool, but it is not limited too that.
At this stage, the main three objects (PD, CQ and QP) are added, and more
will be added later.
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The KBUILD_MODNAME variable contains the module name and it is known for
kernel users during compilation, so let's reuse it to track the owners.
Followup patches will store this for resource tracking.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Each of our modules only allocates a PD in one place, so there isn't any
loss in detail, while MODNAME is more useful and recognizable as something
to expose to the user.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The flags field the enum is used with comes directly from the uapi
so it belongs in the uapi headers for clarity and so userspace can
use it.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
NET_UDP_TUNNEL is not user selectable, so it should be used as a select
in kconfig.
CRYPTO_CRC32 is a required library for RDMA_RXE so it should active
automatically, as most other CRYPTO_ users do.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
qib_keys.c was left uncompilable in commit 7c2e11fe2d ("IB/qib: Remove qp and mr functionality from qib")
Since nothing need it, remove it from tree.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
mthca_user.h is unused since commit 486f60954c ("IB/mthca: Move user vendor structures")
Remove it from tree.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The ndev will be initialized and held only for successful
ib_get_cached_gid(), otherwise it is garbage stack memory.
Calling dev_put() in failure path is wrong.
Fixes: 16c72e4028 ("IB/cm: Refactor to avoid setting path record software only fields")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
When checking whatever the current netdev is the bond master interface,
use kernel API netif_is_bond_master() instead of hardcoding the check.
No functionality is changed.
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
SGID attributes are not used during OPA to IB GID conversion.
Therefore don't query it.
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Failure in XRCD FW deallocation command leaves memory leaked and
returns error to the user which he can't do anything about it.
This patch changes behavior to always free memory and always return
success to the user.
Fixes: e126ba97db ("mlx5: Add driver for Mellanox Connect-IB adapters")
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The ib_write_umad() is protected by taking the umad file mutex.
However, it accesses file->port->ib_dev -- which is protected only by the
port's mutex (field file_mutex).
The ib_umad_remove_one() calls ib_umad_kill_port() which sets
port->ib_dev to NULL under the port mutex (NOT the file mutex).
It then sets the mad agent to "dead" under the umad file mutex.
This is a race condition -- because there is a window where
port->ib_dev is NULL, while the agent is not "dead".
As a result, we saw stack traces like:
[16490.678059] BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0
[16490.678246] IP: ib_umad_write+0x29c/0xa3a [ib_umad]
[16490.678333] PGD 0 P4D 0
[16490.678404] Oops: 0000 [#1] SMP PTI
[16490.678466] Modules linked in: rdma_ucm(OE) ib_ucm(OE) rdma_cm(OE) iw_cm(OE) ib_ipoib(OE) ib_cm(OE) ib_uverbs(OE) ib_umad(OE) mlx4_en(OE) ptp pps_core mlx4_ib(OE-) ib_core(OE) mlx4_core(OE) mlx_compat
(OE) memtrack(OE) devlink mst_pciconf(OE) mst_pci(OE) netconsole nfsv3 nfs_acl nfs lockd grace fscache cfg80211 rfkill esp6_offload esp6 esp4_offload esp4 sunrpc kvm_intel kvm ppdev parport_pc irqbypass
parport joydev i2c_piix4 virtio_balloon cirrus drm_kms_helper ttm drm e1000 serio_raw virtio_pci virtio_ring virtio ata_generic pata_acpi qemu_fw_cfg [last unloaded: mlxfw]
[16490.679202] CPU: 4 PID: 3115 Comm: sminfo Tainted: G OE 4.14.13-300.fc27.x86_64 #1
[16490.679339] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu2 04/01/2014
[16490.679477] task: ffff9cf753890000 task.stack: ffffaf70c26b0000
[16490.679571] RIP: 0010:ib_umad_write+0x29c/0xa3a [ib_umad]
[16490.679664] RSP: 0018:ffffaf70c26b3d90 EFLAGS: 00010202
[16490.679747] RAX: 0000000000000010 RBX: ffff9cf75610fd80 RCX: 0000000000000000
[16490.679856] RDX: 0000000000000001 RSI: 00007ffdf2bfd714 RDI: ffff9cf6bb2a9c00
In the above trace, ib_umad_write is trying to dereference the NULL
file->port->ib_dev pointer.
Fix this by using the agent's device pointer (the device field
in struct ib_mad_agent) -- which IS protected by the umad file mutex.
Cc: <stable@vger.kernel.org> # v4.11
Fixes: 44c58487d5 ("IB/core: Define 'ib' and 'roce' rdma_ah_attr types")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The script "checkpatch.pl" pointed information out like the following.
WARNING: quoted string split across lines
Thus fix the affected source code places.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The variable "tx_desc" will be set to an appropriate pointer a bit later.
Thus omit the explicit initialisation at the beginning.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Omit an extra message for a memory allocation failure in this function.
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Pull x86 retpoline fixlet from Thomas Gleixner:
"Remove the ESP/RSP thunks for retpoline as they cannot ever work.
Get rid of them before they show up in a release"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/retpoline: Remove the esp/rsp thunk
Pull x86 fixes from Thomas Gleixner:
"A set of small fixes for 4.15:
- Fix vmapped stack synchronization on systems with 4-level paging
and a large amount of memory caused by a missing 5-level folding
which made the pgd synchronization logic to fail and causing double
faults.
- Add a missing sanity check in the vmalloc_fault() logic on 5-level
paging systems.
- Bring back protection against accessing a freed initrd in the
microcode loader which was lost by a wrong merge conflict
resolution.
- Extend the Broadwell micro code loading sanity check.
- Add a missing ENDPROC annotation in ftrace assembly code which
makes ORC unhappy.
- Prevent loading the AMD power module on !AMD platforms. The load
itself is uncritical, but an unload attempt results in a kernel
crash.
- Update Peter Anvins role in the MAINTAINERS file"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ftrace: Add one more ENDPROC annotation
x86: Mark hpa as a "Designated Reviewer" for the time being
x86/mm/64: Tighten up vmalloc_fault() sanity checks on 5-level kernels
x86/mm/64: Fix vmapped stack syncing on very-large-memory 4-level systems
x86/microcode: Fix again accessing initrd after having been freed
x86/microcode/intel: Extend BDW late-loading further with LLC size check
perf/x86/amd/power: Do not load AMD power module on !AMD platforms
Pull timer fix from Thomas Gleixner:
"A single fix for a ~10 years old problem which causes high resolution
timers to stop after a CPU unplug/plug cycle due to a stale flag in
the per CPU hrtimer base struct.
Paul McKenney was hunting this for about a year, but the heisenbug
nature made it resistant against debug attempts for quite some time"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hrtimer: Reset hrtimer cpu base proper on CPU hotplug
Pull scheduler fix from Thomas Gleixner:
"A single bug fix to prevent a subtle deadlock in the scheduler core
code vs cpu hotplug"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Fix cpu.max vs. cpuhotplug deadlock
Pull perf fixes from Thomas Gleixner:
"Four patches which all address lock inversions and deadlocks in the
perf core code and the Intel debug store"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86: Fix perf,x86,cpuhp deadlock
perf/core: Fix ctx::mutex deadlock
perf/core: Fix another perf,trace,cpuhp lock inversion
perf/core: Fix lock inversion between perf,trace,cpuhp
Pull locking fixes from Thomas Gleixner:
"Two final locking fixes for 4.15:
- Repair the OWNER_DIED logic in the futex code which got wreckaged
with the recent fix for a subtle race condition.
- Prevent the hard lockup detector from triggering when dumping all
held locks in the system"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Avoid triggering hardlockup from debug_show_all_locks()
futex: Fix OWNER_DEAD fixup
When ORC support was added for the ftrace_64.S code, an ENDPROC
for function_hook() was missed. This results in the following warning:
arch/x86/kernel/ftrace_64.o: warning: objtool: .entry.text+0x0: unreachable instruction
Fixes: e2ac83d74a ("x86/ftrace: Fix ORC unwinding from ftrace handlers")
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20180128022150.dqierscqmt3uwwsr@treble
The hrtimer interrupt code contains a hang detection and mitigation
mechanism, which prevents that a long delayed hrtimer interrupt causes a
continous retriggering of interrupts which prevent the system from making
progress. If a hang is detected then the timer hardware is programmed with
a certain delay into the future and a flag is set in the hrtimer cpu base
which prevents newly enqueued timers from reprogramming the timer hardware
prior to the chosen delay. The subsequent hrtimer interrupt after the delay
clears the flag and resumes normal operation.
If such a hang happens in the last hrtimer interrupt before a CPU is
unplugged then the hang_detected flag is set and stays that way when the
CPU is plugged in again. At that point the timer hardware is not armed and
it cannot be armed because the hang_detected flag is still active, so
nothing clears that flag. As a consequence the CPU does not receive hrtimer
interrupts and no timers expire on that CPU which results in RCU stalls and
other malfunctions.
Clear the flag along with some other less critical members of the hrtimer
cpu base to ensure starting from a clean state when a CPU is plugged in.
Thanks to Paul, Sebastian and Anna-Maria for their help to get down to the
root cause of that hard to reproduce heisenbug. Once understood it's
trivial and certainly justifies a brown paperbag.
Fixes: 41d2e49493 ("hrtimer: Tune hrtimer_interrupt hang logic")
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Sewior <bigeasy@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801261447590.2067@nanos
Due to some unfortunate events, I have not been directly involved in
the x86 kernel patch flow for a while now. I have also not been able
to ramp back up by now like I had hoped to, and after reviewing what I
will need to work on both internally at Intel and elsewhere in the near
term, it is clear that I am not going to be able to ramp back up until
late 2018 at the very earliest.
It is not acceptable to not recognize that this load is currently
taken by Ingo and Thomas without my direct participation, so I mark
myself as R: (designated reviewer) rather than M: (maintainer) until
further notice. This is in fact recognizing the de facto situation
for the past few years.
I have obviously no intention of going away, and I will do everything
within my power to improve Linux on x86 and x86 for Linux. This,
however, puts credit where it is due and reflects a change of focus.
This patch also removes stale entries for portions of the x86
architecture which have not been maintained separately from arch/x86
for a long time. If there is a reason to re-introduce them then that
can happen later.
Signed-off-by: H. Peter Anvin <h.peter.anvin@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Bruce Schlobohm <bruce.schlobohm@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180125195934.5253-1-hpa@zytor.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>