Commit Graph

11856 Commits

Author SHA1 Message Date
Eric Dumazet 8af088710d posix-timers: RCU conversion
Ben Nagy reported a scalability problem with KVM/QEMU that hit very hard
a single spinlock (idr_lock) in posix-timers code, on its 48 core
machine.

Even on a 16 cpu machine (2x4x2), a single test can show 98% of cpu time
used in ticket_spin_lock, from lock_timer

Ref: http://www.spinics.net/lists/kvm/msg51526.html

Switching to RCU is quite easy, IDR being already RCU ready. idr_lock
should be locked only for an insert/delete, not a lookup.

Benchmark on a 2x4x2 machine, 16 processes calling timer_gettime().

Before :

real    1m18.669s
user    0m1.346s
sys     1m17.180s

After :

real    0m3.296s
user    0m1.366s
sys     0m1.926s

Reported-by: Ben Nagy <ben@iagu.net>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Ben Nagy <ben@iagu.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Richard Cochran <richard.cochran@omicron.at>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-24 12:10:51 +02:00
Tejun Heo 6988f20fe0 Merge branch 'fixes-2.6.39' into for-2.6.40 2011-05-24 09:59:36 +02:00
Linus Torvalds 5214638384 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf tools: Fix sample type size calculation in 32 bits archs
  profile: Use vzalloc() rather than vmalloc() & memset()
2011-05-23 21:20:48 -07:00
Linus Torvalds 5f2e8e2b0b kernel/watchdog.c: Use proper ANSI C prototypes
We try to enforce it by using -Wstrict-prototypes, but apparently they
sometimes get through.  Introduced by 4eec42f392 ("watchdog: Change
the default timeout and configure nmi watchdog period based").

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-23 21:07:40 -07:00
Ingo Molnar 6e9101aeec watchdog: Fix non-standard prototype of get_softlockup_thresh()
This build warning slipped through:

  kernel/watchdog.c:102: warning: function declaration isn't a prototype

As reported by Stephen Rothwell.

Also address an unused variable warning that GCC 4.6.0 reports:
we cannot do anything about failed watchdog ops during CPU hotplug
(it's not serious enough to return an error from the notifier),
so ignore them.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20110524134129.8da27016.sfr@canb.auug.org.au
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20110517071642.GF22305@elte.hu>
2011-05-24 05:53:39 +02:00
Rafael J. Wysocki 4e2d9491a7 PM / Hibernate: Update some comments in core hibernate code
Some comments in the core hibernate code are outdated, some aren't
necessary any more and at least one of them is plain wrong.  Remove
those comments or update them.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-24 00:21:26 +02:00
Linus Torvalds 15a3d11b0f Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Increase SCHED_LOAD_SCALE resolution
  sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculations
  sched: Cleanup set_load_weight()
2011-05-23 12:53:48 -07:00
Linus Torvalds 1f3a8e093f Merge branch 'staging-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6
* 'staging-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6: (970 commits)
  staging: usbip: replace usbip_u{dbg,err,info} and printk with dev_ and pr_
  staging:iio: Trivial kconfig reorganization and uniformity improvements.
  staging:iio:documenation partial update.
  staging:iio: use pollfunc allocation helpers in remaining drivers.
  staging:iio:max1363 misc cleanups and use of for_each_bit_set to simplify event code spitting out.
  staging:iio: implement an iio_info structure to take some of the constant elements out of iio_dev.
  staging:iio:meter:ade7758: Use private data space from iio_allocate_device
  staging:iio:accel:lis3l02dq make write_reg_8 take value not a pointer to value.
  staging:iio: ring core cleanups + check if read_last available in lis3l02dq
  staging:iio:core cleanup: squash tiny wrappers and use dev_set_name to handle creation of event interface name.
  staging:iio: poll func allocation clean up.
  staging:iio:ad7780 trivial unused header cleanup.
  staging:iio:adc: AD7780: Use private data space from iio_allocate_device + trivial fixes
  staging:iio:adc:AD7780: Convert to new channel registration method
  staging:iio:adc: AD7606: Drop dev_data in favour of iio_priv()
  staging:iio:adc: AD7606: Consitently use indio_dev
  staging:iio: Rip out helper for software rings.
  staging:iio:adc:AD7298: Use private data space from iio_allocate_device
  staging:iio: rationalization of different buffer implementation hooks.
  staging:iio:imu:adis16400 avoid allocating rx, tx, and state separately from iio_dev.
  ...

Fix up trivial conflicts in
 - drivers/staging/intel_sst/intelmid.c: patches applied in both branches
 - drivers/staging/rt2860/common/cmm_data_{pci,usb}.c: removed vs spelling
 - drivers/staging/usbip/vhci_sysfs.c: trivial header file inclusion
2011-05-23 12:49:28 -07:00
Linus Torvalds 30cb6d5f2e Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimers: Reorder clock bases
  hrtimers: Avoid touching inactive timer bases
  hrtimers: Make struct hrtimer_cpu_base layout less stupid
  timerfd: Manage cancelable timers in timerfd
  clockevents: Move C3 stop test outside lock
  alarmtimer: Drop device refcount after rtc_open()
  alarmtimer: Check return value of class_find_device()
  timerfd: Allow timers to be cancelled when clock was set
  hrtimers: Prepare for cancel on clock was set timers
2011-05-23 11:30:28 -07:00
Linus Torvalds 19504828b4 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf tools: Fix sample size bit operations
  perf tools: Fix ommitted mmap data update on remap
  watchdog: Change the default timeout and configure nmi watchdog period based on watchdog_thresh
  watchdog: Disable watchdog when thresh is zero
  watchdog: Only disable/enable watchdog if neccessary
  watchdog: Fix rounding bug in get_sample_period()
  perf tools: Propagate event parse error handling
  perf tools: Robustify dynamic sample content fetch
  perf tools: Pre-check sample size before parsing
  perf tools: Move evlist sample helpers to evlist area
  perf tools: Remove junk code in mmap size handling
  perf tools: Check we are able to read the event size on mmap
2011-05-23 09:25:52 -07:00
Linus Torvalds 57d19e80f4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits)
  b43: fix comment typo reqest -> request
  Haavard Skinnemoen has left Atmel
  cris: typo in mach-fs Makefile
  Kconfig: fix copy/paste-ism for dell-wmi-aio driver
  doc: timers-howto: fix a typo ("unsgined")
  perf: Only include annotate.h once in tools/perf/util/ui/browsers/annotate.c
  md, raid5: Fix spelling error in comment ('Ofcourse' --> 'Of course').
  treewide: fix a few typos in comments
  regulator: change debug statement be consistent with the style of the rest
  Revert "arm: mach-u300/gpio: Fix mem_region resource size miscalculations"
  audit: acquire creds selectively to reduce atomic op overhead
  rtlwifi: don't touch with treewide double semicolon removal
  treewide: cleanup continuations and remove logging message whitespace
  ath9k_hw: don't touch with treewide double semicolon removal
  include/linux/leds-regulator.h: fix syntax in example code
  tty: fix typo in descripton of tty_termios_encode_baud_rate
  xtensa: remove obsolete BKL kernel option from defconfig
  m68k: fix comment typo 'occcured'
  arch:Kconfig.locks Remove unused config option.
  treewide: remove extra semicolons
  ...
2011-05-23 09:12:26 -07:00
Ingo Molnar 8ce2616955 Merge commit '559fa6e76b27' into perf/urgent
Merge reason: this commit was queued up quite some time ago but was
              forgotten about.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-23 16:15:58 +02:00
Thomas Gleixner 68fa61c026 hrtimers: Reorder clock bases
The ordering of the clock bases is historical due to the
CLOCK_REALTIME and CLOCK_MONOTONIC constants. Now the hrtimer bases
have their own enumeration due to the gap between CLOCK_MONOTONIC and
CLOCK_BOOTTIME. So we can be more clever as most timers end up on the
CLOCK_MONOTONIC base due to the virtue of POSIX declaring that
relative CLOCK_REALTIME timers are not affected by time changes. In
desktop environments this is slowly changing as applications switch to
absolute timers, but I've observed empty CLOCK_REALTIME bases often
enough. There is no performance penalty or overhead when
CLOCK_REALTIME timers are active, but in case they are not we don't
skip over a full cache line.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2011-05-23 13:59:54 +02:00
Thomas Gleixner ab8177bc53 hrtimers: Avoid touching inactive timer bases
Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2011-05-23 13:59:54 +02:00
Thomas Gleixner 9ec2690758 timerfd: Manage cancelable timers in timerfd
Peter is concerned about the extra scan of CLOCK_REALTIME_COS in the
timer interrupt. Yes, I did not think about it, because the solution
was so elegant. I didn't like the extra list in timerfd when it was
proposed some time ago, but with a rcu based list the list walk it's
less horrible than the original global lock, which was held over the
list iteration.

Requested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2011-05-23 13:59:53 +02:00
Mandeep Singh Baines 4eec42f392 watchdog: Change the default timeout and configure nmi watchdog period based on watchdog_thresh
Before the conversion of the NMI watchdog to perf event, the
watchdog timeout was 5 seconds. Now it is 60 seconds. For my
particular application, netbooks, 5 seconds was a better
timeout. With a short timeout, we catch faults earlier and are
able to send back a panic. With a 60 second timeout, the user is
unlikely to wait and will instead hit the power button, causing
us to lose the panic info.

This change configures the NMI period to watchdog_thresh and
sets the softlockup_thresh to watchdog_thresh * 2. In addition,
watchdog_thresh was reduced to 10 seconds as suggested by Ingo
Molnar.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1306127423-3347-4-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20110517071642.GF22305@elte.hu>
2011-05-23 11:58:59 +02:00
Mandeep Singh Baines 586692a5a5 watchdog: Disable watchdog when thresh is zero
This restores the previous behavior of softlock_thresh.

Currently, setting watchdog_thresh to zero causes the watchdog
kthreads to consume a lot of CPU.

In addition, the logic of proc_dowatchdog_thresh and
proc_dowatchdog_enabled has been factored into proc_dowatchdog.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1306127423-3347-3-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20110517071018.GE22305@elte.hu>
2011-05-23 11:58:59 +02:00
Mandeep Singh Baines e04ab2bc41 watchdog: Only disable/enable watchdog if neccessary
Don't take any action on an unsuccessful write to /proc.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1306127423-3347-2-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-23 11:58:58 +02:00
Mandeep Singh Baines 824c6b7f62 watchdog: Fix rounding bug in get_sample_period()
In get_sample_period(), softlockup_thresh is integer divided by
5 before the multiplication by NSEC_PER_SEC. This results in
softlockup_thresh being rounded down to the nearest integer
multiple of 5.

For example, a softlockup_thresh of 4 rounds down to 0.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1306127423-3347-1-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-23 11:58:58 +02:00
Linus Torvalds e98bae7592 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6: (28 commits)
  sparc32: fix build, fix missing cpu_relax declaration
  SCHED_TTWU_QUEUE is not longer needed since sparc32 now implements IPI
  sparc32,leon: Remove unnecessary page_address calls in LEON DMA API.
  sparc: convert old cpumask API into new one
  sparc32, sun4d: Implemented SMP IPIs support for SUN4D machines
  sparc32, sun4m: Implemented SMP IPIs support for SUN4M machines
  sparc32,leon: Implemented SMP IPIs for LEON CPU
  sparc32: implement SMP IPIs using the generic functions
  sparc32,leon: SMP power down implementation
  sparc32,leon: added some SMP comments
  sparc: add {read,write}*_be routines
  sparc32,leon: don't rely on bootloader to mask IRQs
  sparc32,leon: operate on boot-cpu IRQ controller registers
  sparc32: always define boot_cpu_id
  sparc32: removed unused code, implemented by generic code
  sparc32: avoid build warning at mm/percpu.c:1647
  sparc32: always register a PROM based early console
  sparc32: probe for cpu info only during startup
  sparc: consolidate show_cpuinfo in cpu.c
  sparc32,leon: implement genirq CPU affinity
  ...
2011-05-22 22:06:24 -07:00
Kevin Cernekee be84bfcc3e ipc: Add missing sys_ni entries for ipc/compat.c functions
When building with:

  CONFIG_64BIT=y
  CONFIG_MIPS32_COMPAT=y
  CONFIG_COMPAT=y
  CONFIG_MIPS32_O32=y
  CONFIG_MIPS32_N32=y
  CONFIG_SYSVIPC is not set
  (and implicitly: CONFIG_SYSVIPC_COMPAT is not set)

the final link fails with unresolved symbols for:

  compat_sys_semctl, compat_sys_msgsnd, compat_sys_msgrcv,
  compat_sys_shmctl, compat_sys_msgctl, compat_sys_semtimedop

The fix is to add cond_syscall declarations for all syscalls in
ipc/compat.c

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-20 13:53:02 -07:00
Linus Torvalds 06f4e926d2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1446 commits)
  macvlan: fix panic if lowerdev in a bond
  tg3: Add braces around 5906 workaround.
  tg3: Fix NETIF_F_LOOPBACK error
  macvlan: remove one synchronize_rcu() call
  networking: NET_CLS_ROUTE4 depends on INET
  irda: Fix error propagation in ircomm_lmp_connect_response()
  irda: Kill set but unused variable 'bytes' in irlan_check_command_param()
  irda: Kill set but unused variable 'clen' in ircomm_connect_indication()
  rxrpc: Fix set but unused variable 'usage' in rxrpc_get_transport()
  be2net: Kill set but unused variable 'req' in lancer_fw_download()
  irda: Kill set but unused vars 'saddr' and 'daddr' in irlan_provider_connect_indication()
  atl1c: atl1c_resume() is only used when CONFIG_PM_SLEEP is defined.
  rxrpc: Fix set but unused variable 'usage' in rxrpc_get_peer().
  rxrpc: Kill set but unused variable 'local' in rxrpc_UDP_error_handler()
  rxrpc: Kill set but unused variable 'sp' in rxrpc_process_connection()
  rxrpc: Kill set but unused variable 'sp' in rxrpc_rotate_tx_window()
  pkt_sched: Kill set but unused variable 'protocol' in tc_classify()
  isdn: capi: Use pr_debug() instead of ifdefs.
  tg3: Update version to 3.119
  tg3: Apply rx_discards fix to 5719/5720
  ...

Fix up trivial conflicts in arch/x86/Kconfig and net/mac80211/agg-tx.c
as per Davem.
2011-05-20 13:43:21 -07:00
Linus Torvalds 102dc1bae1 Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  MAINTAINERS: Add drivers/clocksource to TIMEKEEPING
  clockevents/source: Use u64 to make 32bit happy
2011-05-20 13:38:28 -07:00
Linus Torvalds bc091c93a0 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  extable, core_kernel_data(): Make sure all archs define _sdata
  core_kernel_data(): Fix architectures that do not define _sdata
2011-05-20 13:37:22 -07:00
Linus Torvalds 3ed4c0583d Merge branch 'ptrace' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc
* 'ptrace' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc: (41 commits)
  signal: trivial, fix the "timespec declared inside parameter list" warning
  job control: reorganize wait_task_stopped()
  ptrace: fix signal->wait_chldexit usage in task_clear_group_stop_trapping()
  signal: sys_sigprocmask() needs retarget_shared_pending()
  signal: cleanup sys_sigprocmask()
  signal: rename signandsets() to sigandnsets()
  signal: do_sigtimedwait() needs retarget_shared_pending()
  signal: introduce do_sigtimedwait() to factor out compat/native code
  signal: sys_rt_sigtimedwait: simplify the timeout logic
  signal: cleanup sys_rt_sigprocmask()
  x86: signal: sys_rt_sigreturn() should use set_current_blocked()
  x86: signal: handle_signal() should use set_current_blocked()
  signal: sigprocmask() should do retarget_shared_pending()
  signal: sigprocmask: narrow the scope of ->siglock
  signal: retarget_shared_pending: optimize while_each_thread() loop
  signal: retarget_shared_pending: consider shared/unblocked signals only
  signal: introduce retarget_shared_pending()
  ptrace: ptrace_check_attach() should not do s/STOPPED/TRACED/
  signal: Turn SIGNAL_STOP_DEQUEUED into GROUP_STOP_DEQUEUED
  signal: do_signal_stop: Remove the unneeded task_clear_group_stop_pending()
  ...
2011-05-20 13:33:21 -07:00
Daniel Hellstrom 17d9f311ec SCHED_TTWU_QUEUE is not longer needed since sparc32 now implements IPI
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-05-20 13:10:55 -07:00
David S. Miller 90d3ac15e5 Merge commit '317f394160e9beb97d19a84c39b7e5eb3d7815a8'
Conflicts:
	arch/sparc/kernel/smp_32.c

With merge conflict help from Daniel Hellstrom.

Signed-off-by: David S. Miller <davem@davemloft.net>
2011-05-20 13:10:22 -07:00
Linus Torvalds 268bb0ce3e sanitize <linux/prefetch.h> usage
Commit e66eed651f ("list: remove prefetching from regular list
iterators") removed the include of prefetch.h from list.h, which
uncovered several cases that had apparently relied on that rather
obscure header file dependency.

So this fixes things up a bit, using

   grep -L linux/prefetch.h $(git grep -l '[^a-z_]prefetchw*(' -- '*.[ch]')
   grep -L 'prefetchw*(' $(git grep -l 'linux/prefetch.h' -- '*.[ch]')

to guide us in finding files that either need <linux/prefetch.h>
inclusion, or have it despite not needing it.

There are more of them around (mostly network drivers), but this gets
many core ones.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-20 12:50:29 -07:00
Thomas Gleixner 250f972d85 Merge branch 'timers/urgent' into timers/core
Reason: Get upstream fixes and kfree_rcu which is necessary for a
follow up patch.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-20 20:08:05 +02:00
Nikhil Rao c8b281161d sched: Increase SCHED_LOAD_SCALE resolution
Introduce SCHED_LOAD_RESOLUTION, which scales is added to
SCHED_LOAD_SHIFT and increases the resolution of
SCHED_LOAD_SCALE. This patch sets the value of
SCHED_LOAD_RESOLUTION to 10, scaling up the weights for all
sched entities by a factor of 1024. With this extra resolution,
we can handle deeper cgroup hiearchies and the scheduler can do
better shares distribution and load load balancing on larger
systems (especially for low weight task groups).

This does not change the existing user interface, the scaled
weights are only used internally. We do not modify
prio_to_weight values or inverses, but use the original weights
when calculating the inverse which is used to scale execution
time delta in calc_delta_mine(). This ensures we do not lose
accuracy when accounting time to the sched entities. Thanks to
Nikunj Dadhania for fixing an bug in c_d_m() that broken fairness.

Below is some analysis of the performance costs/improvements of
this patch.

1. Micro-arch performance costs:

Experiment was to run Ingo's pipe_test_100k 200 times with the
task pinned to one cpu. I measured instruction, cycles and
stalled-cycles for the runs. See:

   http://thread.gmane.org/gmane.linux.kernel/1129232/focus=1129389

for more info.

-tip (baseline):

 Performance counter stats for '/root/load-scale/pipe-test-100k' (200 runs):

       964,991,769 instructions             #    0.82  insns per cycle
                                            #    0.33  stalled cycles per insn
                                            #    ( +-  0.05% )
     1,171,186,635 cycles                   #    0.000 GHz                      ( +-  0.08% )
       306,373,664 stalled-cycles-backend   #   26.16% backend  cycles idle     ( +-  0.28% )
       314,933,621 stalled-cycles-frontend  #   26.89% frontend cycles idle     ( +-  0.34% )

        1.122405684  seconds time elapsed  ( +-  0.05% )

-tip+patches:

 Performance counter stats for './load-scale/pipe-test-100k' (200 runs):

       963,624,821 instructions             #    0.82  insns per cycle
                                            #    0.33  stalled cycles per insn
                                            #    ( +-  0.04% )
     1,175,215,649 cycles                   #    0.000 GHz                      ( +-  0.08% )
       315,321,126 stalled-cycles-backend   #   26.83% backend  cycles idle     ( +-  0.28% )
       316,835,873 stalled-cycles-frontend  #   26.96% frontend cycles idle     ( +-  0.29% )

        1.122238659  seconds time elapsed  ( +-  0.06% )

With this patch, instructions decrease by ~0.10% and cycles
increase by 0.27%. This doesn't look statistically significant.
The number of stalled cycles in the backend increased from
26.16% to 26.83%. This can be attributed to the shifts we do in
c_d_m() and other places. The fraction of stalled cycles in the
frontend remains about the same, at 26.96% compared to 26.89% in -tip.

2. Balancing low-weight task groups

Test setup: run 50 tasks with random sleep/busy times (biased
around 100ms) in a low weight container (with cpu.shares = 2).
Measure %idle as reported by mpstat over a 10s window.

-tip (baseline):

06:47:48 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle    intr/s
06:47:49 PM  all   94.32    0.00    0.06    0.00    0.00    0.00    0.00    0.00    5.62  15888.00
06:47:50 PM  all   94.57    0.00    0.62    0.00    0.00    0.00    0.00    0.00    4.81  16180.00
06:47:51 PM  all   94.69    0.00    0.06    0.00    0.00    0.00    0.00    0.00    5.25  15966.00
06:47:52 PM  all   95.81    0.00    0.00    0.00    0.00    0.00    0.00    0.00    4.19  16053.00
06:47:53 PM  all   94.88    0.06    0.00    0.00    0.00    0.00    0.00    0.00    5.06  15984.00
06:47:54 PM  all   93.31    0.00    0.00    0.00    0.00    0.00    0.00    0.00    6.69  15806.00
06:47:55 PM  all   94.19    0.00    0.06    0.00    0.00    0.00    0.00    0.00    5.75  15896.00
06:47:56 PM  all   92.87    0.00    0.00    0.00    0.00    0.00    0.00    0.00    7.13  15716.00
06:47:57 PM  all   94.88    0.00    0.00    0.00    0.00    0.00    0.00    0.00    5.12  15982.00
06:47:58 PM  all   95.44    0.00    0.00    0.00    0.00    0.00    0.00    0.00    4.56  16075.00
Average:     all   94.49    0.01    0.08    0.00    0.00    0.00    0.00    0.00    5.42  15954.60

-tip+patches:

06:47:03 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle    intr/s
06:47:04 PM  all  100.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  16630.00
06:47:05 PM  all   99.69    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.31  16580.20
06:47:06 PM  all   99.69    0.00    0.06    0.00    0.00    0.00    0.00    0.00    0.25  16596.00
06:47:07 PM  all   99.20    0.00    0.74    0.00    0.00    0.06    0.00    0.00    0.00  17838.61
06:47:08 PM  all  100.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  16540.00
06:47:09 PM  all  100.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  16575.00
06:47:10 PM  all  100.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  16614.00
06:47:11 PM  all   99.94    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.06  16588.00
06:47:12 PM  all   99.94    0.00    0.06    0.00    0.00    0.00    0.00    0.00    0.00  16593.00
06:47:13 PM  all   99.94    0.00    0.06    0.00    0.00    0.00    0.00    0.00    0.00  16551.00
Average:     all   99.84    0.00    0.09    0.00    0.00    0.01    0.00    0.00    0.06  16711.58

We see an improvement in idle% on the system (drops from 5.42% on -tip to 0.06%
with the patches).

We see an improvement in idle% on the system (drops from 5.42%
on -tip to 0.06% with the patches).

Signed-off-by: Nikhil Rao <ncrao@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1305754668-18792-1-git-send-email-ncrao@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20 14:16:50 +02:00
Nikhil Rao 1399fa7807 sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculations
SCHED_LOAD_SCALE is used to increase nice resolution and to
scale cpu_power calculations in the scheduler. This patch
introduces SCHED_POWER_SCALE and converts all uses of
SCHED_LOAD_SCALE for scaling cpu_power to use SCHED_POWER_SCALE
instead.

This is a preparatory patch for increasing the resolution of
SCHED_LOAD_SCALE, and there is no need to increase resolution
for cpu_power calculations.

Signed-off-by: Nikhil Rao <ncrao@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de>
Cc: Mike Galbraith <efault@gmx.de>
Link: http://lkml.kernel.org/r/1305738580-9924-3-git-send-email-ncrao@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20 14:16:50 +02:00
Nikhil Rao f05998d4b8 sched: Cleanup set_load_weight()
Avoid using long repetitious names; make this simpler and nicer
to read. No functional change introduced in this patch.

Signed-off-by: Nikhil Rao <ncrao@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de>
Cc: Mike Galbraith <efault@gmx.de>
Link: http://lkml.kernel.org/r/1305738580-9924-2-git-send-email-ncrao@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20 14:16:49 +02:00
Thomas Gleixner c0e299b1a9 clockevents/source: Use u64 to make 32bit happy
unsigned long is not 64bit on 32bit machine.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-20 10:50:52 +02:00
Steven Rostedt a2d063ac21 extable, core_kernel_data(): Make sure all archs define _sdata
A new utility function (core_kernel_data()) is used to determine if a
passed in address is part of core kernel data or not. It may or may not
return true for RO data, but this utility must work for RW data.

Thus both _sdata and _edata must be defined and continuous,
without .init sections that may later be freed and replaced by
volatile memory (memory that can be freed).

This utility function is used to determine if data is safe from
ever being freed. Thus it should return true for all RW global
data that is not in a module or has been allocated, or false
otherwise.

Also change core_kernel_data() back to the more precise _sdata condition
and document the function.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Hirokazu Takata <takata@linux-m32r.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: JamesE.J.Bottomley <jejb@parisc-linux.org>
Link: http://lkml.kernel.org/r/1305855298.1465.19.camel@gandalf.stny.rr.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
----
 arch/alpha/kernel/vmlinux.lds.S   |    1 +
 arch/m32r/kernel/vmlinux.lds.S    |    1 +
 arch/m68k/kernel/vmlinux-std.lds  |    2 ++
 arch/m68k/kernel/vmlinux-sun3.lds |    1 +
 arch/mips/kernel/vmlinux.lds.S    |    1 +
 arch/parisc/kernel/vmlinux.lds.S  |    3 +++
 kernel/extable.c                  |   12 +++++++++++-
 7 files changed, 20 insertions(+), 1 deletion(-)
2011-05-20 08:56:56 +02:00
Ingo Molnar c16dbd54a3 Merge branch 'perf/core' into perf/urgent
Merge reason: One pending commit was left in perf/core after Linus merged
              perf/core - continue v2.6.40 work in the perf/urgent reason.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20 08:54:08 +02:00
Chris Metcalf 571d76acda arch/tile: support signal "exception-trace" hook
This change adds support for /proc/sys/debug/exception-trace to tile.
Like x86 and sparc, by default it is set to "1", generating a one-line
printk whenever a user process crashes.  By setting it to "2", we get
a much more complete userspace diagnostic at crash time, including
a user-space backtrace, register dump, and memory dump around the
address of the crash.

Some vestiges of the Tilera-internal version of this support are
removed with this patch (the show_crashinfo variable and the
arch_coredump_signal function).  We retain a "crashinfo" boot parameter
which allows you to set the boot-time value of exception-trace.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2011-05-19 22:55:59 -04:00
Linus Torvalds 39ab05c8e0 Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6
* 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6: (44 commits)
  debugfs: Silence DEBUG_STRICT_USER_COPY_CHECKS=y warning
  sysfs: remove "last sysfs file:" line from the oops messages
  drivers/base/memory.c: fix warning due to "memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER_SECTION"
  memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER_SECTION
  SYSFS: Fix erroneous comments for sysfs_update_group().
  driver core: remove the driver-model structures from the documentation
  driver core: Add the device driver-model structures to kerneldoc
  Translated Documentation/email-clients.txt
  RAW driver: Remove call to kobject_put().
  reboot: disable usermodehelper to prevent fs access
  efivars: prevent oops on unload when efi is not enabled
  Allow setting of number of raw devices as a module parameter
  Introduce CONFIG_GOOGLE_FIRMWARE
  driver: Google Memory Console
  driver: Google EFI SMI
  x86: Better comments for get_bios_ebda()
  x86: get_bios_ebda_length()
  misc: fix ti-st build issues
  params.c: Use new strtobool function to process boolean inputs
  debugfs: move to new strtobool
  ...

Fix up trivial conflicts in fs/debugfs/file.c due to the same patch
being applied twice, and an unrelated cleanup nearby.
2011-05-19 18:24:11 -07:00
Linus Torvalds eb04f2f04e Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (78 commits)
  Revert "rcu: Decrease memory-barrier usage based on semi-formal proof"
  net,rcu: convert call_rcu(prl_entry_destroy_rcu) to kfree
  batman,rcu: convert call_rcu(softif_neigh_free_rcu) to kfree_rcu
  batman,rcu: convert call_rcu(neigh_node_free_rcu) to kfree()
  batman,rcu: convert call_rcu(gw_node_free_rcu) to kfree_rcu
  net,rcu: convert call_rcu(kfree_tid_tx) to kfree_rcu()
  net,rcu: convert call_rcu(xt_osf_finger_free_rcu) to kfree_rcu()
  net/mac80211,rcu: convert call_rcu(work_free_rcu) to kfree_rcu()
  net,rcu: convert call_rcu(wq_free_rcu) to kfree_rcu()
  net,rcu: convert call_rcu(phonet_device_rcu_free) to kfree_rcu()
  perf,rcu: convert call_rcu(swevent_hlist_release_rcu) to kfree_rcu()
  perf,rcu: convert call_rcu(free_ctx) to kfree_rcu()
  net,rcu: convert call_rcu(__nf_ct_ext_free_rcu) to kfree_rcu()
  net,rcu: convert call_rcu(net_generic_release) to kfree_rcu()
  net,rcu: convert call_rcu(netlbl_unlhsh_free_addr6) to kfree_rcu()
  net,rcu: convert call_rcu(netlbl_unlhsh_free_addr4) to kfree_rcu()
  security,rcu: convert call_rcu(sel_netif_free) to kfree_rcu()
  net,rcu: convert call_rcu(xps_dev_maps_release) to kfree_rcu()
  net,rcu: convert call_rcu(xps_map_release) to kfree_rcu()
  net,rcu: convert call_rcu(rps_map_release) to kfree_rcu()
  ...
2011-05-19 18:14:34 -07:00
Linus Torvalds 78c4def67e Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimer: Make lookup table const
  RTC: Disable CONFIG_RTC_CLASS from being built as a module
  timers: Fix alarmtimer build issues when CONFIG_RTC_CLASS=n
  timers: Remove delayed irqwork from alarmtimers implementation
  timers: Improve alarmtimer comments and minor fixes
  timers: Posix interface for alarm-timers
  timers: Introduce in-kernel alarm-timer interface
  timers: Add rb_init_node() to allow for stack allocated rb nodes
  time: Add timekeeping_inject_sleeptime
2011-05-19 17:45:08 -07:00
Linus Torvalds 7e6628e4bc Merge branch 'timers-clockevents-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-clockevents-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: hpet: Cleanup the clockevents init and register code
  x86: Convert PIT to clockevents_config_and_register()
  clockevents: Provide interface to reconfigure an active clock event device
  clockevents: Provide combined configure and register function
  clockevents: Restructure clock_event_device members
  clocksource: Get rid of the hardcoded 5 seconds sleep time limit
  clocksource: Restructure clocksource struct members
2011-05-19 17:44:40 -07:00
Linus Torvalds 80fe02b5da Merge branches 'sched-core-for-linus' and 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (60 commits)
  sched: Fix and optimise calculation of the weight-inverse
  sched: Avoid going ahead if ->cpus_allowed is not changed
  sched, rt: Update rq clock when unthrottling of an otherwise idle CPU
  sched: Remove unused parameters from sched_fork() and wake_up_new_task()
  sched: Shorten the construction of the span cpu mask of sched domain
  sched: Wrap the 'cfs_rq->nr_spread_over' field with CONFIG_SCHED_DEBUG
  sched: Remove unused 'this_best_prio arg' from balance_tasks()
  sched: Remove noop in alloc_rt_sched_group()
  sched: Get rid of lock_depth
  sched: Remove obsolete comment from scheduler_tick()
  sched: Fix sched_domain iterations vs. RCU
  sched: Next buddy hint on sleep and preempt path
  sched: Make set_*_buddy() work on non-task entities
  sched: Remove need_migrate_task()
  sched: Move the second half of ttwu() to the remote cpu
  sched: Restructure ttwu() some more
  sched: Rename ttwu_post_activation() to ttwu_do_wakeup()
  sched: Remove rq argument from ttwu_stat()
  sched: Remove rq->lock from the first half of ttwu()
  sched: Drop rq->lock from sched_exec()
  ...

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Fix rt_rq runtime leakage bug
2011-05-19 17:41:22 -07:00
Linus Torvalds df48d8716e Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (107 commits)
  perf stat: Add more cache-miss percentage printouts
  perf stat: Add -d -d and -d -d -d options to show more CPU events
  ftrace/kbuild: Add recordmcount files to force full build
  ftrace: Add self-tests for multiple function trace users
  ftrace: Modify ftrace_set_filter/notrace to take ops
  ftrace: Allow dynamically allocated function tracers
  ftrace: Implement separate user function filtering
  ftrace: Free hash with call_rcu_sched()
  ftrace: Have global_ops store the functions that are to be traced
  ftrace: Add ops parameter to ftrace_startup/shutdown functions
  ftrace: Add enabled_functions file
  ftrace: Use counters to enable functions to trace
  ftrace: Separate hash allocation and assignment
  ftrace: Create a global_ops to hold the filter and notrace hashes
  ftrace: Use hash instead for FTRACE_FL_FILTER
  ftrace: Replace FTRACE_FL_NOTRACE flag with a hash of ignored functions
  perf bench, x86: Add alternatives-asm.h wrapper
  x86, 64-bit: Fix copy_[to/from]_user() checks for the userspace address limit
  x86, mem: memset_64.S: Optimize memset by enhanced REP MOVSB/STOSB
  x86, mem: memmove_64.S: Optimize memmove by enhanced REP MOVSB/STOSB
  ...
2011-05-19 17:36:08 -07:00
Linus Torvalds acd30250d7 Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  irq: Export functions to allow modular irq drivers
  genirq: Uninline and sanity check generic_handle_irq()
  genirq: Remove pointless ifdefs
  genirq: Make generic irq chip depend on CONFIG_GENERIC_IRQ_CHIP
  genirq: Add chip suspend and resume callbacks
  genirq: Implement a generic interrupt chip
  genirq: Support per-IRQ thread disabling.
  genirq: irq_desc: Document preflow_handler and affinity_hint
  genirq: Update DocBook comments
  genirq: Forgotten updates/deletions after removal of compat code
2011-05-19 17:30:15 -07:00
Linus Torvalds 6595b4a940 Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  seqlock: Don't smp_rmb in seqlock reader spin loop
  watchdog, hung_task_timeout: Add Kconfig configurable default
  lockdep: Remove cmpxchg to update nr_chain_hlocks
  lockdep: Print a nicer description for simple irq lock inversions
  lockdep: Replace "Bad BFS generated tree" message with something less cryptic
  lockdep: Print a nicer description for irq inversion bugs
  lockdep: Print a nicer description for simple deadlocks
  lockdep: Print a nicer description for normal deadlocks
  lockdep: Print a nicer description for irq lock inversions
2011-05-19 17:29:29 -07:00
Linus Torvalds 51509a283a Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6: (34 commits)
  PM: Introduce generic prepare and complete callbacks for subsystems
  PM: Allow drivers to allocate memory from .prepare() callbacks safely
  PM: Remove CONFIG_PM_VERBOSE
  Revert "PM / Hibernate: Reduce autotuned default image size"
  PM / Hibernate: Add sysfs knob to control size of memory for drivers
  PM / Wakeup: Remove useless synchronize_rcu() call
  kmod: always provide usermodehelper_disable()
  PM / ACPI: Remove acpi_sleep=s4_nonvs
  PM / Wakeup: Fix build warning related to the "wakeup" sysfs file
  PM: Print a warning if firmware is requested when tasks are frozen
  PM / Runtime: Rework runtime PM handling during driver removal
  Freezer: Use SMP barriers
  PM / Suspend: Do not ignore error codes returned by suspend_enter()
  PM: Fix build issue in clock_ops.c for CONFIG_PM_RUNTIME unset
  PM: Revert "driver core: platform_bus: allow runtime override of dev_pm_ops"
  OMAP1 / PM: Use generic clock manipulation routines for runtime PM
  PM: Remove sysdev suspend, resume and shutdown operations
  PM / PowerPC: Use struct syscore_ops instead of sysdevs for PM
  PM / UNICORE32: Use struct syscore_ops instead of sysdevs for PM
  PM / AVR32: Use struct syscore_ops instead of sysdevs for PM
  ...
2011-05-19 16:46:07 -07:00
Ingo Molnar c5fc472171 core_kernel_data(): Fix architectures that do not define _sdata
Some architectures such as Alpha do not define _sdata but _data:

  kernel/built-in.o: In function `core_kernel_data':
  kernel/extable.c:77: undefined reference to `_sdata'

So expand the scope of the data range to the text addresses too,
this might be more correct anyway because this way we can
cover readonly variables as well.

Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-i878c8a0e0g0ep4v7i6vxnhz@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20 01:27:16 +02:00
Randy Dunlap d410fa4ef9 Create Documentation/security/,
move LSM-, credentials-, and keys-related files from Documentation/
  to Documentation/security/,
add Documentation/security/00-INDEX, and
update all occurrences of Documentation/<moved_file>
  to Documentation/security/<moved_file>.
2011-05-19 15:59:38 -07:00
Paul E. McKenney 80d02085d9 Revert "rcu: Decrease memory-barrier usage based on semi-formal proof"
This reverts commit e59fb3120b.

This reversion was due to (extreme) boot-time slowdowns on SPARC seen by
Yinghai Lu and on x86 by Ingo
.
This is a non-trivial reversion due to intervening commits.

Conflicts:

	Documentation/RCU/trace.txt
	kernel/rcutree.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-19 23:25:29 +02:00
Thomas Gleixner 80b816b736 clockevents: Provide interface to reconfigure an active clock event device
Some ARM SoCs have clock event devices which have their frequency
modified due to frequency scaling. Provide an interface which allows
to reconfigure an active device. After reconfiguration reprogram the
current pending event.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/%3C20110518210136.437459958%40linutronix.de%3E
2011-05-19 14:24:16 +02:00
Thomas Gleixner 57f0fcbe1d clockevents: Provide combined configure and register function
All clockevent devices have the same open coded initialization
functions. Provide an interface which does all necessary
initialization in the core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/%3C20110518210136.331975870%40linutronix.de%3E
2011-05-19 14:24:15 +02:00
Thomas Gleixner 724ed53e8a clocksource: Get rid of the hardcoded 5 seconds sleep time limit
Slow clocksources can have a way longer sleep time than 5 seconds and
even fast ones can easily cope with 600 seconds and still maintain
proper accuracy.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/%3C20110518210136.109811585%40linutronix.de%3E
2011-05-19 14:24:15 +02:00
James Morris 12a5a2621b Merge branch 'master' into next
Conflicts:
	include/linux/capability.h

Manually resolve merge conflict w/ thanks to Stephen Rothwell.

Signed-off-by: James Morris <jmorris@namei.org>
2011-05-19 18:51:57 +10:00
Jonathan Cameron f721a465cd params.c: Use new strtobool function to process boolean inputs
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:28 +09:30
Alessio Igor Bogani 9d63487f86 module: Use binary search in lookup_symbol()
The function is_exported() with its helper function lookup_symbol() are used to
verify if a provided symbol is effectively exported by the kernel or by the
modules. Now that both have their symbols sorted we can replace a linear search
with a binary search which provide a considerably speed-up.

This work was supported by a hardware donation from the CE Linux Forum.

Signed-off-by: Alessio Igor Bogani <abogani@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:27 +09:30
Alessio Igor Bogani 403ed27846 module: Use the binary search for symbols resolution
Takes advantage of the order and locates symbols using binary search.

This work was supported by a hardware donation from the CE Linux Forum.

Signed-off-by: Alessio Igor Bogani <abogani@kernel.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Tested-by: Dirk Behme <dirk.behme@googlemail.com>
2011-05-19 16:55:27 +09:30
Rusty Russell de4d8d5346 module: each_symbol_section instead of each_symbol
Instead of having a callback function for each symbol in the kernel,
have a callback for each array of symbols.

This eases the logic when we move to sorted symbols and binary search.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Alessio Igor Bogani <abogani@kernel.org>
2011-05-19 16:55:26 +09:30
Jan Glauber 01526ed083 module: split unset_section_ro_nx function.
Split the unprotect function into a function per section to make
the code more readable and add the missing static declaration.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:26 +09:30
Jan Glauber 448694a1d5 module: undo module RONX protection correctly.
While debugging I stumbled over two problems in the code that protects module
pages.

First issue is that disabling the protection before freeing init or unload of
a module is not symmetric with the enablement. For instance, if pages are set
to RO the page range from module_core to module_core + core_ro_size is
protected. If a module is unloaded the page range from module_core to
module_core + core_size is set back to RW.
So pages that were not set to RO are also changed to RW.
This is not critical but IMHO it should be symmetric.

Second issue is that while set_memory_rw & set_memory_ro are used for
RO/RW changes only set_memory_nx is involved for NX/X. One would await that
the inverse function is called when the NX protection should be removed,
which is not the case here, unless I'm missing something.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:26 +09:30
Jan Glauber 4d10380e72 module: zero mod->init_ro_size after init is freed.
Reset mod->init_ro_size to zero after the init part of a module is unloaded.
Otherwise we need to check if module->init is NULL in the unprotect functions
in the next patch.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:26 +09:30
Daniel J Blueman 5d05c70849 minor ANSI prototype sparse fix
Fix function prototype to be ANSI-C compliant, consistent with other
function prototypes, addressing a sparse warning.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:25 +09:30
Dmitry Torokhov b4bc842802 module: deal with alignment issues in built-in module versions
On m68k natural alignment is 2-byte boundary but we are trying to
align structures in __modver section on sizeof(void *) boundary.
This causes trouble when we try to access elements in this section
in array-like fashion when create "version" attributes for built-in
modules.

Moreover, as DaveM said, we can't reliably put structures into
independent objects, put them into a special section, and then expect
array access over them (via the section boundaries) after linking the
objects together to just "work" due to variable alignment choices in
different situations. The only solution that seems to work reliably
is to make an array of plain pointers to the objects in question and
put those pointers in the special section.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-19 16:55:24 +09:30
Steven Rostedt 95950c2ecb ftrace: Add self-tests for multiple function trace users
Add some basic sanity tests for multiple users of the function
tracer at startup.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 19:24:51 -04:00
Steven Rostedt 936e074b28 ftrace: Modify ftrace_set_filter/notrace to take ops
Since users of the function tracer can now pick and choose which
functions they want to trace agnostically from other users of the
function tracer, we need to pass the ops struct to the ftrace_set_filter()
functions.

The functions ftrace_set_global_filter() and ftrace_set_global_notrace()
is added to keep the old filter functions which are used to modify
the generic function tracers.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 19:22:52 -04:00
Steven Rostedt cdbe61bfe7 ftrace: Allow dynamically allocated function tracers
Now that functions may be selected individually, it only makes sense
that we should allow dynamically allocated trace structures to
be traced. This will allow perf to allocate a ftrace_ops structure
at runtime and use it to pick and choose which functions that
structure will trace.

Note, a dynamically allocated ftrace_ops will always be called
indirectly instead of being called directly from the mcount in
entry.S. This is because there's no safe way to prevent mcount
from being preempted before calling the function, unless we
modify every entry.S to do so (not likely). Thus, dynamically allocated
functions will now be called by the ftrace_ops_list_func() that
loops through the ops that are allocated if there are more than
one op allocated at a time. This loop is protected with a
preempt_disable.

To determine if an ftrace_ops structure is allocated or not, a new
util function was added to the kernel/extable.c called
core_kernel_data(), which returns 1 if the address is between
_sdata and _edata.

Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:51 -04:00
Steven Rostedt b848914ce3 ftrace: Implement separate user function filtering
ftrace_ops that are registered to trace functions can now be
agnostic to each other in respect to what functions they trace.
Each ops has their own hash of the functions they want to trace
and a hash to what they do not want to trace. A empty hash for
the functions they want to trace denotes all functions should
be traced that are not in the notrace hash.

Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:50 -04:00
Steven Rostedt 07fd5515f3 ftrace: Free hash with call_rcu_sched()
When a hash is modified and might be in use, we need to perform
a schedule RCU operation on it, as the hashes will soon be used
directly in the function tracer callback.

Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:50 -04:00
Steven Rostedt 2b499381bc ftrace: Have global_ops store the functions that are to be traced
This is a step towards each ops structure defining its own set
of functions to trace. As the current code with pid's and such
are specific to the global_ops, it is restructured to be used
with the global ops.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:49 -04:00
Steven Rostedt bd69c30b1d ftrace: Add ops parameter to ftrace_startup/shutdown functions
In order to allow different ops to enable different functions,
the ftrace_startup() and ftrace_shutdown() functions need the
ops parameter passed to them.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:48 -04:00
Steven Rostedt 647bcd03d5 ftrace: Add enabled_functions file
Add the enabled_functions file that is used to show all the
functions that have been enabled for tracing as well as their
ref counts. This helps seeing if any function has been registered
and what functions are being traced.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:47 -04:00
Steven Rostedt ed926f9b35 ftrace: Use counters to enable functions to trace
Every function has its own record that stores the instruction
pointer and flags for the function to be traced. There are only
two flags: enabled and free. The enabled flag states that tracing
for the function has been enabled (actively traced), and the free
flag states that the record no longer points to a function and can
be used by new functions (loaded modules).

These flags are now moved to the MSB of the flags (actually just
the top 32bits). The rest of the bits (30 bits) are now used as
a ref counter. Everytime a tracer register functions to trace,
those functions will have its counter incremented.

When tracing is enabled, to determine if a function should be traced,
the counter is examined, and if it is non-zero it is set to trace.

When a ftrace_ops is registered to trace functions, its hashes
are examined. If the ftrace_ops filter_hash count is zero, then
all functions are set to be traced, otherwise only the functions
in the hash are to be traced. The exception to this is if a function
is also in the ftrace_ops notrace_hash. Then that function's counter
is not incremented for this ftrace_ops.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:47 -04:00
Steven Rostedt 33dc9b1267 ftrace: Separate hash allocation and assignment
When filtering, allocate a hash to insert the function records.
After the filtering is complete, assign it to the ftrace_ops structure.

This allows the ftrace_ops structure to have a much smaller array of
hash buckets instead of wasting a lot of memory.

A read only empty_hash is created to be the minimum size that any ftrace_ops
can point to.

When a new hash is created, it has the following steps:

o Allocate a default hash.
o Walk the function records assigning the filtered records to the hash
o Allocate a new hash with the appropriate size buckets
o Move the entries from the default hash to the new hash.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:46 -04:00
Steven Rostedt f45948e898 ftrace: Create a global_ops to hold the filter and notrace hashes
Combine the filter and notrace hashes to be accessed by a single entity,
the global_ops. The global_ops is a ftrace_ops structure that is passed
to different functions that can read or modify the filtering of the
function tracer.

The ftrace_ops structure was modified to hold a filter and notrace
hashes so that later patches may allow each ftrace_ops to have its own
set of rules to what functions may be filtered.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:45 -04:00
Steven Rostedt 1cf41dd799 ftrace: Use hash instead for FTRACE_FL_FILTER
When multiple users are allowed to have their own set of functions
to trace, having the FTRACE_FL_FILTER flag will not be enough to
handle the accounting of those users. Each user will need their own
set of functions.

Replace the FTRACE_FL_FILTER with a filter_hash instead. This is
temporary until the rest of the function filtering accounting
gets in.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:44 -04:00
Steven Rostedt b448c4e3ae ftrace: Replace FTRACE_FL_NOTRACE flag with a hash of ignored functions
To prepare for the accounting system that will allow multiple users of
the function tracer, having the FTRACE_FL_NOTRACE as a flag in the
dyn_trace record does not make sense.

All ftrace_ops will soon have a hash of functions they should trace
and not trace. By making a global hash of functions not to trace makes
this easier for the transition.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-18 15:29:44 -04:00
Jonathan Cameron edf76f8307 irq: Export functions to allow modular irq drivers
Export handle_simple_irq, irq_modify_status, irq_alloc_descs,
irq_free_descs and generic_handle_irq to allow their usage in
modules. First user is IIO, which wants to be built modular, but needs
to be able to create irq chips, allocate and configure interrupt
descriptors and handle demultiplexing interrupts.

[ tglx: Moved the uninlinig of generic_handle_irq to a separate patch ]

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Link: http://lkml.kernel.org/r/%3C1305711544-505-1-git-send-email-jic23%40cam.ac.uk%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-18 14:59:08 +02:00
Thomas Gleixner fe12bc2c99 genirq: Uninline and sanity check generic_handle_irq()
generic_handle_irq() is missing a NULL pointer check for the result of
irq_to_desc. This was a not a big problem, but we want to expose it to
drivers, so we better have sanity checks in place. Add a return value
as well, which indicates that the irq number was valid and the handler
was invoked.

Based on the pure code move from Jonathan Cameron.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
2011-05-18 14:59:08 +02:00
Thomas Gleixner fe05143484 genirq: Remove pointless ifdefs
kernel/irq/ is only built when CONFIG_GENERIC_HARDIRQS=y. So making
code inside of kernel/irq/ conditional on CONFIG_GENERIC_HARDIRQS is
pointless.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-18 14:59:07 +02:00
Rafael J. Wysocki 91e7c75ba9 PM: Allow drivers to allocate memory from .prepare() callbacks safely
If device drivers allocate substantial amounts of memory (above 1 MB)
in their hibernate .freeze() callbacks (or in their legacy suspend
callbcks during hibernation), the subsequent creation of hibernate
image may fail due to the lack of memory.  This is the case, because
the drivers' .freeze() callbacks are executed after the hibernate
memory preallocation has been carried out and the preallocated amount
of memory may be too small to cover the new driver allocations.
Unfortunately, the drivers' .prepare() callbacks also are executed
after the hibernate memory preallocation has completed, so they are
not suitable for allocating additional memory either.  Thus the only
way a driver can safely allocate memory during hibernation is to use
a hibernate/suspend notifier.  However, the notifiers are called
before the freezing of user space and the drivers wanting to use them
for allocating additional memory may not know how much memory needs
to be allocated at that point.

To let device drivers overcome this difficulty rework the hibernation
sequence so that the memory preallocation is carried out after the
drivers' .prepare() callbacks have been executed, so that the
.prepare() callbacks can be used for allocating additional memory
to be used by the drivers' .freeze() callbacks.  Update documentation
to match the new behavior of the code.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:26:00 +02:00
Rafael J. Wysocki c650da23d5 PM: Remove CONFIG_PM_VERBOSE
Now that we have CONFIG_DYNAMIC_DEBUG there is no need for yet
another flag causing dev_dbg() and pr_debug() statements in the
core PM code to produce output.  Moreover, CONFIG_PM_VERBOSE
causes so much output to be generated that it's not really useful
and almost no one sets it.

References: https://bugzilla.kernel.org/show_bug.cgi?id=23182
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:25:10 +02:00
Rafael J. Wysocki 290c748725 Merge branch 'power-domains' into for-linus
* power-domains:
  PM: Fix build issue in clock_ops.c for CONFIG_PM_RUNTIME unset
  PM: Revert "driver core: platform_bus: allow runtime override of dev_pm_ops"
  OMAP1 / PM: Use generic clock manipulation routines for runtime PM
  PM / Runtime: Generic clock manipulation rountines for runtime PM (v6)
  PM / Runtime: Add subsystem data field to struct dev_pm_info
  OMAP2+ / PM: move runtime PM implementation to use device power domains
  PM / Platform: Use generic runtime PM callbacks directly
  shmobile: Use power domains for platform runtime PM
  PM: Export platform bus type's default PM callbacks
  PM: Make power domain callbacks take precedence over subsystem ones
2011-05-17 23:23:46 +02:00
Rafael J. Wysocki 2d2a9163bd Merge branch 'syscore' into for-linus
* syscore:
  PM: Remove sysdev suspend, resume and shutdown operations
  PM / PowerPC: Use struct syscore_ops instead of sysdevs for PM
  PM / UNICORE32: Use struct syscore_ops instead of sysdevs for PM
  PM / AVR32: Use struct syscore_ops instead of sysdevs for PM
  PM / Blackfin: Use struct syscore_ops instead of sysdevs for PM
  ARM / Samsung: Use struct syscore_ops for "core" power management
  ARM / PXA: Use struct syscore_ops for "core" power management
  ARM / SA1100: Use struct syscore_ops for "core" power management
  ARM / Integrator: Use struct syscore_ops for core PM
  ARM / OMAP: Use struct syscore_ops for "core" power management
  ARM: Use struct syscore_ops instead of sysdevs for PM in common code
2011-05-17 23:23:40 +02:00
Rafael J. Wysocki 1c1be3a949 Revert "PM / Hibernate: Reduce autotuned default image size"
This reverts commit bea3864fb6
(PM / Hibernate: Reduce autotuned default image size), because users
are now able to resolve the issue this commit was supposed to address
in a different way (i.e. by using the new /sys/power/reserved_size
interface).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:19:19 +02:00
Rafael J. Wysocki ddeb648708 PM / Hibernate: Add sysfs knob to control size of memory for drivers
Martin reports that on his system hibernation occasionally fails due
to the lack of memory, because the radeon driver apparently allocates
too much of it during the device freeze stage.  It turns out that the
amount of memory allocated by radeon during hibernation (and
presumably during system suspend too) depends on the utilization of
the GPU (e.g. hibernating while there are two KDE 4 sessions with
compositing enabled causes radeon to allocate more memory than for
one KDE 4 session).

In principle it should be possible to use image_size to make the
memory preallocation mechanism free enough memory for the radeon
driver, but in practice it is not easy to guess the right value
because of the way the preallocation code uses image_size.  For this
reason, it seems reasonable to allow users to control the amount of
memory reserved for driver allocations made after the hibernate
preallocation, which currently is constant and amounts to 1 MB.

Introduce a new sysfs file, /sys/power/reserved_size, whose value
will be used as the amount of memory to reserve for the
post-preallocation reservations made by device drivers, in bytes.
For backwards compatibility, set its default (and initial) value to
the currently used number (1 MB).

References: https://bugzilla.kernel.org/show_bug.cgi?id=34102
Reported-and-tested-by: Martin Steigerwald <Martin@Lichtvoll.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:19:19 +02:00
Kay Sievers 13d53f8775 kmod: always provide usermodehelper_disable()
We need to prevent kernel-forked processes during system poweroff.
Such processes try to access the filesystem whose disks we are
trying to shutdown at the same time. This causes delays and exceptions
in the storage drivers.

A follow-up patch will add these calls and need usermodehelper_disable()
also on systems without suspend support.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:19:18 +02:00
Rafael J. Wysocki a144c6a6c9 PM: Print a warning if firmware is requested when tasks are frozen
Some drivers erroneously use request_firmware() from their ->resume()
(or ->thaw(), or ->restore()) callbacks, which is not going to work
unless the firmware has been built in.  This causes system resume to
stall until the firmware-loading timeout expires, which makes users
think that the resume has failed and reboot their machines
unnecessarily.  For this reason, make _request_firmware() print a
warning and return immediately with error code if it has been called
when tasks are frozen and it's impossible to start any new usermode
helpers.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Reviewed-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
2011-05-17 23:19:17 +02:00
Mike Frysinger ee940d8dcc Freezer: Use SMP barriers
The freezer processes are dealing with multiple threads running
simultaneously, and on a UP system, the memory reads/writes do
not need barriers to keep things in sync.  These are only needed
on SMP systems, so use SMP barriers instead.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:19:17 +02:00
MyungJoo Ham 3c43193608 PM / Suspend: Do not ignore error codes returned by suspend_enter()
The current implementation of suspend-to-RAM returns 0 if there is an
error from suspend_enter(), because suspend_devices_and_enter() ignores
the return value from suspend_enter().  This patch addresses this issue
and properly keep the error return from suspend_enter() and let
suspend_devices_and_enter relay the error return.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17 23:19:16 +02:00
Linus Torvalds a085963a27 Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tick: Clear broadcast active bit when switching to oneshot
  rtc: mc13xxx: Don't call rtc_device_register while holding lock
  rtc: rp5c01: Initialize drvdata before registering device
  rtc: pcap: Initialize drvdata before registering device
  rtc: msm6242: Initialize drvdata before registering device
  rtc: max8998: Initialize drvdata before registering device
  rtc: max8925: Initialize drvdata before registering device
  rtc: m41t80: Initialize clientdata before registering device
  rtc: ds1286: Initialize drvdata before registering device
  rtc: ep93xx: Initialize drvdata before registering device
  rtc: davinci: Initialize drvdata before registering device
  rtc: mxc: Initialize drvdata before registering device
  clocksource: Install completely before selecting
2011-05-17 08:02:04 -07:00
Thomas Gleixner 07f4beb0b5 tick: Clear broadcast active bit when switching to oneshot
The first cpu which switches from periodic to oneshot mode switches
also the broadcast device into oneshot mode. The broadcast device
serves as a backup for per cpu timers which stop in deeper
C-states. To avoid starvation of the cpus which might be in idle and
depend on broadcast mode it marks the other cpus as broadcast active
and sets the brodcast expiry value of those cpus to the next tick.

The oneshot mode broadcast bit for the other cpus is sticky and gets
only cleared when those cpus exit idle. If a cpu was not idle while
the bit got set in consequence the bit prevents that the broadcast
device is armed on behalf of that cpu when it enters idle for the
first time after it switched to oneshot mode.

In most cases that goes unnoticed as one of the other cpus has usually
a timer pending which keeps the broadcast device armed with a short
timeout. Now if the only cpu which has a short timer active has the
bit set then the broadcast device will not be armed on behalf of that
cpu and will fire way after the expected timer expiry. In the case of
Christians bug report it took ~145 seconds which is about half of the
wrap around time of HPET (the limit for that device) due to the fact
that all other cpus had no timers armed which expired before the 145
seconds timeframe.

The solution is simply to clear the broadcast active bit
unconditionally when a cpu switches to oneshot mode after the first
cpu switched the broadcast device over. It's not idle at that point
otherwise it would not be executing that code.

[ I fundamentally hate that broadcast crap. Why the heck thought some
  folks that when going into deep idle it's a brilliant concept to
  switch off the last device which brings the cpu back from that
  state? ]

Thanks to Christian for providing all the valuable debug information!

Reported-and-tested-by: Christian Hoffmann <email@christianhoffmann.info>
Cc: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1105161105170.3078%40ionos%3E
Cc: stable@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-16 23:35:41 +02:00
Stephan Baerwolf db670dac49 sched: Fix and optimise calculation of the weight-inverse
If the inverse loadweight should be zero, function "calc_delta_mine"
calculates the inverse of "lw->weight" (in 32bit integer ops).

This calculation is actually a little bit impure (because it is
inverting something around "lw-weight"+1), especially when
"lw->weight" becomes smaller.

The correct inverse would be 1/lw->weight multiplied by
"WMULT_CONST" for fixcomma-scaling it into integers.
(So WMULT_CONST/lw->weight ...)

The old, impure algorithm took two divisions for inverting lw->weight,
the new, more exact one only takes one and an additional unlikely-if.

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-0pz0wnyalr4tk4ln11xwumdx@git.kernel.org
[ This could explain some aritmetical issues for small shares but nothing
  concrete has been reported yet so we are not confident enough to queue
  this up in sched/urgent and for -stable backport. But if anyone finds
  this commit and sees it to fix some badness then we can certainly
  change our mind! ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16 11:01:18 +02:00
Yong Zhang db44fc017d sched: Avoid going ahead if ->cpus_allowed is not changed
If cpumask_equal(&p->cpus_allowed, new_mask) is true, seems
there is no reason to prevent set_cpus_allowed_ptr() return
directly.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Acked-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110509140705.GA2219@zhy
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16 11:01:18 +02:00
Mike Galbraith 61eadef6a9 sched, rt: Update rq clock when unthrottling of an otherwise idle CPU
If an RT task is awakened while it's rt_rq is throttled, the time between
wakeup/enqueue and unthrottle/selection may be accounted as rt_time
if the CPU is idle.  Set rq->skip_clock_update negative upon throttle
release to tell put_prev_task() that we need a clock update.

Reported-by: Thomas Giesel <skoe@directbox.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1304059010.7472.1.camel@marge.simson.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16 11:01:17 +02:00
Cheng Xu ec514c487c sched: Fix rt_rq runtime leakage bug
This patch is to fix the real-time scheduler bug reported at:

  https://lkml.org/lkml/2011/4/26/13

That is, when running multiple real-time threads on every logical CPUs
and then turning off one CPU, the kernel will bug at function
__disable_runtime().

Function __disable_runtime() bugs and reports leakage of rt_rq runtime.
The root cause is __disable_runtime() assumes it iterates through all
the existing rt_rq's while walking rq->leaf_rt_rq_list, which actually
contains only runnable rt_rq's. This problem also applies to
__enable_runtime() and print_rt_stats().

The patch is based on above analysis, appears to fix the problem, but is
only lightly tested.

Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Cheng Xu <chengxu@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4DCE1F12.6040609@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16 11:00:54 +02:00
Serge E. Hallyn 47a150edc2 Cache user_ns in struct cred
If !CONFIG_USERNS, have current_user_ns() defined to (&init_user_ns).

Get rid of _current_user_ns.  This requires nsown_capable() to be
defined in capability.c rather than as static inline in capability.h,
so do that.

Request_key needs init_user_ns defined at current_user_ns if
!CONFIG_USERNS, so forward-declare that in cred.h if !CONFIG_USERNS
at current_user_ns() define.

Compile-tested with and without CONFIG_USERNS.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
[ This makes a huge performance difference for acl_permission_check(),
  up to 30%.  And that is one of the hottest kernel functions for loads
  that are pathname-lookup heavy.  ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-13 11:45:33 -07:00
Tejun Heo 19e274630c job control: reorganize wait_task_stopped()
wait_task_stopped() tested task_stopped_code() without acquiring
siglock and, if stop condition existed, called wait_task_stopped() and
directly returned the result.  This patch moves the initial
task_stopped_code() testing into wait_task_stopped() and make
wait_consider_task() fall through to wait_task_continue() on 0 return.

This is for the following two reasons.

* Because the initial task_stopped_code() test is done without
  acquiring siglock, it may race against SIGCONT generation.  The
  stopped condition might have been replaced by continued state by the
  time wait_task_stopped() acquired siglock.  This may lead to
  unexpected failure of WNOHANG waits.

  This reorganization addresses this single race case but there are
  other cases - TASK_RUNNING -> TASK_STOPPED transition and EXIT_*
  transitions.

* Scheduled ptrace updates require changes to the initial test which
  would fit better inside wait_task_stopped().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2011-05-13 18:56:02 +02:00
Chris Metcalf be84cb4383 compat: fixes to allow working with tile arch
The existing <asm-generic/unistd.h> mechanism doesn't really provide
enough to create the 64-bit "compat" ABI properly in a generic way,
since the compat ABI is a mix of things were you can re-use the 64-bit
versions of syscalls and things where you need a compat wrapper.

To provide this in the most direct way possible, I added two new macros
to go along with the existing __SYSCALL and __SC_3264 macros: __SC_COMP
and SC_COMP_3264.  These macros take an additional argument, typically a
"compat_sys_xxx" function, which is passed to __SYSCALL if you define
__SYSCALL_COMPAT when including the header, resulting in a pointer to
the compat function being placed in the generated syscall table.

The change also adds some missing definitions to <linux/compat.h> so that
it actually has declarations for all the compat syscalls, since the
"[nr] = ##call" approach requires proper C declarations for all the
functions included in the syscall table.

Finally, compat.c defines compat_sys_sigpending() and
compat_sys_sigprocmask() even if the underlying architecture doesn't
request it, which tries to pull in undefined compat_old_sigset_t defines.
We need to guard those compat syscall definitions with appropriate
__ARCH_WANT_SYS_xxx ifdefs.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2011-05-12 15:51:36 -04:00
Samir Bellabes 3e51e3edfd sched: Remove unused parameters from sched_fork() and wake_up_new_task()
sched_fork() and wake_up_new_task() are defined with a parameter
'unsigned long clone_flags', which is unused.

This patch removes the parameters.

Signed-off-by: Samir Bellabes <sam@synack.fr>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1305130685-1047-1-git-send-email-sam@synack.fr
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-12 09:36:37 +02:00
Ingo Molnar 9cb5baba5e Merge commit 'v2.6.39-rc7' into sched/core 2011-05-12 09:36:18 +02:00
Rafael J. Wysocki 2e711c04db PM: Remove sysdev suspend, resume and shutdown operations
Since suspend, resume and shutdown operations in struct sysdev_class
and struct sysdev_driver are not used any more, remove them.  Also
drop sysdev_suspend(), sysdev_resume() and sysdev_shutdown() used
for executing those operations and modify all of their users
accordingly.  This reduces kernel code size quite a bit and reduces
its complexity.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-05-11 21:37:15 +02:00
Rafael J. Wysocki 36cb7035ea PM / Hibernate: Fix ioctl SNAPSHOT_S2RAM
The SNAPSHOT_S2RAM ioctl used for implementing the feature allowing
one to suspend to RAM after creating a hibernation image is currently
broken, because it doesn't clear the "ready" flag in the struct
snapshot_data object handled by it.  As a result, the
SNAPSHOT_UNFREEZE doesn't work correctly after SNAPSHOT_S2RAM has
returned and the user space hibernate task cannot thaw the other
processes as appropriate.  Make SNAPSHOT_S2RAM clear data->ready
to fix this problem.

Tested-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@kernel.org
2011-05-11 21:10:58 +02:00
Rafael J. Wysocki 9744997a8a PM / Hibernate: Make snapshot_release() restore GFP mask
If the process using the hibernate user space interface closes
/dev/snapshot after creating a hibernation image without thawing
tasks, snapshot_release() should call pm_restore_gfp_mask() to
restore the GFP mask used before the creation of the image.  Make
that happen.

Tested-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@kernel.org
2011-05-11 21:10:43 +02:00
Rafael J. Wysocki 87186475a4 PM: Fix warning in pm_restrict_gfp_mask() during SNAPSHOT_S2RAM ioctl
A warning is printed by pm_restrict_gfp_mask() while the
SNAPSHOT_S2RAM ioctl is being executed after creating a hibernation
image, because pm_restrict_gfp_mask() has been called once already
before the image creation and suspend_devices_and_enter() calls it
once again.  This happens after commit 452aa6999e
(mm/pm: force GFP_NOIO during suspend/hibernation and resume).

To avoid this issue, move pm_restrict_gfp_mask() and
pm_restore_gfp_mask() from suspend_devices_and_enter() to its caller
in kernel/power/suspend.c.

Reported-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@kernel.org
2011-05-11 21:10:14 +02:00
Eric W. Biederman 34482e89a5 ns proc: Add support for the uts namespace
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2011-05-10 14:35:35 -07:00
Eric W. Biederman 0663c6f8fa ns: Introduce the setns syscall
With the networking stack today there is demand to handle
multiple network stacks at a time.  Not in the context
of containers but in the context of people doing interesting
things with routing.

There is also demand in the context of containers to have
an efficient way to execute some code in the container itself.
If nothing else it is very useful ad a debugging technique.

Both problems can be solved by starting some form of login
daemon in the namespaces people want access to, or you
can play games by ptracing a process and getting the
traced process to do things you want it to do. However
it turns out that a login daemon or a ptrace puppet
controller are more code, they are more prone to
failure, and generally they are less efficient than
simply changing the namespace of a process to a
specified one.

Pieces of this puzzle can also be solved by instead of
coming up with a general purpose system call coming up
with targed system calls perhaps socketat that solve
a subset of the larger problem.  Overall that appears
to be more work for less reward.

int setns(int fd, int nstype);

The fd argument is a file descriptor referring to a proc
file of the namespace you want to switch the process to.

In the setns system call the nstype is 0 or specifies
an clone flag of the namespace you intend to change
to prevent changing a namespace unintentionally.

v2: Most of the architecture support added by Daniel Lezcano <dlezcano@fr.ibm.com>
v3: ported to v2.6.36-rc4 by: Eric W. Biederman <ebiederm@xmission.com>
v4: Moved wiring up of the system call to another patch
v5: Cleaned up the system call arguments
    - Changed the order.
    - Modified nstype to take the standard clone flags.
v6: Added missing error handling as pointed out by Matt Helsley <matthltc@us.ibm.com>

Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2011-05-10 14:32:56 -07:00
Ingo Molnar 932fed4e2e Merge commit 'v2.6.39-rc7' into perf/core
Merge reason: pull in the latest fixes.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-10 17:05:45 +02:00
Tejun Heo 40ae717d1e ptrace: fix signal->wait_chldexit usage in task_clear_group_stop_trapping()
GROUP_STOP_TRAPPING waiting mechanism piggybacks on
signal->wait_chldexit which is primarily used to implement waiting for
wait(2) and friends.  When do_wait() waits on signal->wait_chldexit,
it uses a custom wake up callback, child_wait_callback(), which
expects the child task which is waking up the parent to be passed in
as @key to filter out spurious wakeups.

task_clear_group_stop_trapping() used __wake_up_sync() which uses NULL
@key causing the following oops if the parent was doing do_wait().

  BUG: unable to handle kernel NULL pointer dereference at 00000000000002d8
  IP: [<ffffffff810499f9>] child_wait_callback+0x29/0x80
  PGD 1d899067 PUD 1e418067 PMD 0
  Oops: 0000 [#1] PREEMPT SMP
  last sysfs file: /sys/devices/pci0000:00/0000:00:03.0/local_cpus
  CPU 2
  Modules linked in:

  Pid: 4498, comm: test-continued Not tainted 2.6.39-rc6-work+ #32 Bochs Bochs
  RIP: 0010:[<ffffffff810499f9>]  [<ffffffff810499f9>] child_wait_callback+0x29/0x80
  RSP: 0000:ffff88001b889bf8  EFLAGS: 00010046
  RAX: 0000000000000000 RBX: ffff88001fab3af8 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff88001d91df20
  RBP: ffff88001b889c08 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
  R13: ffff88001fb70550 R14: 0000000000000000 R15: 0000000000000001
  FS:  00007f26ccae4700(0000) GS:ffff88001fd00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
  CR2: 00000000000002d8 CR3: 000000001b8ac000 CR4: 00000000000006e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
  Process test-continued (pid: 4498, threadinfo ffff88001b888000, task ffff88001fb88000)
  Stack:
   ffff88001b889c18 ffff88001fb70538 ffff88001b889c58 ffffffff810312f9
   0000000000000001 0000000200000001 ffff88001b889c58 ffff88001fb70518
   0000000000000002 0000000000000082 0000000000000001 0000000000000000
  Call Trace:
   [<ffffffff810312f9>] __wake_up_common+0x59/0x90
   [<ffffffff81035263>] __wake_up_sync_key+0x53/0x80
   [<ffffffff810352a0>] __wake_up_sync+0x10/0x20
   [<ffffffff8105a984>] task_clear_jobctl_trapping+0x44/0x50
   [<ffffffff8105bcbc>] ptrace_stop+0x7c/0x290
   [<ffffffff8105c20a>] do_signal_stop+0x28a/0x2d0
   [<ffffffff8105d27f>] get_signal_to_deliver+0x14f/0x5a0
   [<ffffffff81002175>] do_signal+0x75/0x7b0
   [<ffffffff8100292d>] do_notify_resume+0x5d/0x70
   [<ffffffff8182e36a>] retint_signal+0x46/0x8c
  Code: 00 00 55 48 89 e5 53 48 83 ec 08 0f 1f 44 00 00 8b 47 d8 83 f8 03 74 3a 85 c0 49 89 c8 75 23 89 c0 48 8b 5f e0 4c 8d 0c 40 31 c0 <4b> 39 9c c8 d8 02 00 00 74 1d 48 83 c4 08 5b c9 c3 66 0f 1f 44

Fix it by using __wake_up_sync_key() and passing in the child as @key.

I still think it's a mistake to piggyback on wait_chldexit for this.
Given the relative low frequency of ptrace use, we would be much
better off leaving already complex wait_chldexit alone and using bit
waitqueue.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
2011-05-09 14:19:54 +02:00
Oleg Nesterov 2e4f7c7769 signal: sys_sigprocmask() needs retarget_shared_pending()
sys_sigprocmask() changes current->blocked by hand. Convert this code
to use set_current_blocked().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2011-05-09 13:48:56 +02:00
Lai Jiangshan fa4bbc4ca5 perf,rcu: convert call_rcu(swevent_hlist_release_rcu) to kfree_rcu()
The rcu callback swevent_hlist_release_rcu() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(swevent_hlist_release_rcu).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07 22:51:09 -07:00
Lai Jiangshan cb796ff338 perf,rcu: convert call_rcu(free_ctx) to kfree_rcu()
The rcu callback free_ctx() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(free_ctx).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07 22:51:08 -07:00
Lai Jiangshan 025cea99db cgroup,rcu: convert call_rcu(__free_css_id_cb) to kfree_rcu()
The rcu callback __free_css_id_cb() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(__free_css_id_cb).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07 22:50:47 -07:00
Lai Jiangshan f2da1c40dc cgroup,rcu: convert call_rcu(free_cgroup_rcu) to kfree_rcu()
The rcu callback free_cgroup_rcu() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(free_cgroup_rcu).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07 22:50:46 -07:00
Lai Jiangshan 30088ad815 cgroup,rcu: convert call_rcu(free_css_set_rcu) to kfree_rcu()
The rcu callback free_css_set_rcu() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(free_css_set_rcu).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07 22:50:45 -07:00
Paul E. McKenney 1217ed1ba5 rcu: permit rcu_read_unlock() to be called while holding runqueue locks
Avoid calling into the scheduler while holding core RCU locks.  This
allows rcu_read_unlock() to be called while holding the runqueue locks,
but only as long as there was no chance of the RCU read-side critical
section having been preempted.  (Otherwise, if RCU priority boosting
is enabled, rcu_read_unlock() might call into the scheduler in order to
unboost itself, which might allows self-deadlock on the runqueue locks
within the scheduler.)

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-07 22:50:45 -07:00
Linus Torvalds 8b061610da Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf tools: Makefile: Use gcc to determine ARCH
  perf events, x86: Fix Intel Nehalem and Westmere last level cache event definitions
  hw_breakpoints, powerpc: Fix CONFIG_HAVE_HW_BREAKPOINT off-case in ptrace_set_debugreg()
  sh, hw_breakpoints: Fix racy access to ptrace breakpoints
  arm, hw_breakpoints: Fix racy access to ptrace breakpoints
  powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints
  x86, hw_breakpoints: Fix racy access to ptrace breakpoints
  ptrace: Prepare to fix racy accesses on task breakpoints
2011-05-07 13:17:37 -07:00
Kay Sievers b50fa7c807 reboot: disable usermodehelper to prevent fs access
In case CONFIG_UEVENT_HELPER_PATH is not set to "", which it
should be on every system, the kernel forks processes during
shutdown, which try to access the rootfs, even when the
binary does not exist. It causes exceptions and long delays in
the disk driver, which gets read requests at the time it tries
to shut down the disk.

This patch disables all kernel-forked processes during reboot to
allow a clean poweroff.

Cc: Tejun Heo <htejun@gmail.com>
Tested-By: Anton Guda <atu@dmeti.dp.ua>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-05-06 17:52:32 -07:00
Arjan van de Ven a3a4a5acd3 Regression: partial revert "tracing: Remove lock_depth from event entry"
This partially reverts commit e6e1e25935.

That commit changed the structure layout of the trace structure, which
in turn broke PowerTOP (1.9x generation) quite badly.

I appreciate not wanting to expose the variable in question, and
PowerTOP was not using it, so I've replaced the variable with just a
padding field - that way if in the future a new field is needed it can
just use this padding field.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-06 13:20:59 -07:00
Hillf Danton 7142d17e8f sched: Shorten the construction of the span cpu mask of sched domain
For a given node, when constructing the cpumask for its
sched_domain to span, if there is no best node available after
searching, further efforts could be saved, based on small change
in the return value of find_next_best_node().

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Link: http://lkml.kernel.org/r/BANLkTi%3DqPWxRAa6%2BdT3ohEP6Z%3D0v%2Be4EXA@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-06 09:13:05 +02:00
Rakib Mullick 4934a4d3d3 sched: Wrap the 'cfs_rq->nr_spread_over' field with CONFIG_SCHED_DEBUG
cfs_rq->nr_spread_over is only used when CONFIG_SCHED_DEBUG is set.
So wrap it with CONFIG_SCHED_DEBUG.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1304528026.15681.3.camel@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-06 09:04:19 +02:00
Gleb Natapov 29ce831000 rcu: provide rcu_virt_note_context_switch() function.
Provide rcu_virt_note_context_switch() for vitalization use to note
quiescent state during guest entry.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:59 -07:00
Paul E. McKenney bad6e1393c rcu: get rid of signed overflow in check_cpu_stall()
Signed integer overflow is undefined by the C standard, so move
calculations to unsigned.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:59 -07:00
Eric Dumazet b554d7de8d rcu: optimize rcutiny
rcu_sched_qs() currently calls local_irq_save()/local_irq_restore() up
to three times.

Remove irq masking from rcu_qsctr_help() / invoke_rcu_kthread()
and do it once in rcu_sched_qs() / rcu_bh_qs()

This generates smaller code as well.

   text	   data	    bss	    dec	    hex	filename
   2314	    156	     24	   2494	    9be	kernel/rcutiny.old.o
   2250	    156	     24	   2430	    97e	kernel/rcutiny.new.o

Fix an outdated comment for rcu_qsctr_help()
Move invoke_rcu_kthread() definition before its use.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:59 -07:00
Paul E. McKenney 2655d57ef3 rcu: prevent call_rcu() from diving into rcu core if irqs disabled
This commit marks a first step towards making call_rcu() have
real-time behavior.  If irqs are disabled, don't dive into the
RCU core.  Later on, this new early exit will wake up the
per-CPU kthread, which first must be modified to handle the
cases involving callback storms.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:59 -07:00
Paul E. McKenney baa1ae0c9f rcu: further lower priority in rcu_yield()
Although rcu_yield() dropped from real-time to normal priority, there
is always the possibility that the competing tasks have been niced.
So nice to 19 in rcu_yield() to help ensure that other tasks have a
better chance of running.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:59 -07:00
Lai Jiangshan 9ab1544eb4 rcu: introduce kfree_rcu()
Many rcu callbacks functions just call kfree() on the base structure.
These functions are trivial, but their size adds up, and furthermore
when they are used in a kernel module, that module must invoke the
high-latency rcu_barrier() function at module-unload time.

The kfree_rcu() function introduced by this commit addresses this issue.
Rather than encoding a function address in the embedded rcu_head
structure, kfree_rcu() instead encodes the offset of the rcu_head
structure within the base structure.  Because the functions are not
allowed in the low-order 4096 bytes of kernel virtual memory, offsets
up to 4095 bytes can be accommodated.  If the offset is larger than
4095 bytes, a compile-time error will be generated in __kfree_rcu().
If this error is triggered, you can either fall back to use of call_rcu()
or rearrange the structure to position the rcu_head structure into the
first 4096 bytes.

Note that the allowable offset might decrease in the future, for example,
to allow something like kmem_cache_free_rcu().

The new kfree_rcu() function can replace code as follows:

	call_rcu(&p->rcu, simple_kfree_callback);

where "simple_kfree_callback()" might be defined as follows:

	void simple_kfree_callback(struct rcu_head *p)
	{
		struct foo *q = container_of(p, struct foo, rcu);

		kfree(q);
	}

with the following:

	kfree_rcu(&p->rcu, rcu);

Note that the "rcu" is the name of a field in the structure being
freed.  The reason for using this rather than passing in a pointer
to the base structure is that the above approach allows better type
checking.

This commit is based on earlier work by Lai Jiangshan and Manfred Spraul:

Lai's V1 patch: http://lkml.org/lkml/2008/9/18/1
Manfred's patch: http://lkml.org/lkml/2009/1/2/115

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:59 -07:00
Paul E. McKenney 6cc68793e3 rcu: fix spelling
The "preemptible" spelling is preferable.  May as well fix it.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:59 -07:00
Lai Jiangshan 13491a0ee1 rcu: call __rcu_read_unlock() in exit_rcu for tree RCU
Using __rcu_read_lock() in place of rcu_read_lock() leaves any debug
state as it really should be, namely with the lock still held.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:58 -07:00
Paul E. McKenney 7e8b4c7234 rcu: Converge TINY_RCU expedited and normal boosting
This applies a trick from TREE_RCU boosting to TINY_RCU, eliminating
code and adding comments.  The key point is that it is possible for
the booster thread itself to work out whether there is a normal or
expedited boost required based solely on local information.  There
is therefore no need for boost initiation to know or care what type
of boosting is required.  In addition, when boosting is complete for
a given grace period, then by definition there cannot be any more
boosting for that grace period.  This allows eliminating yet more
state and statistics.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:58 -07:00
Paul E. McKenney 203373c81b rcu: remove useless ->boosted_this_gp field
The ->boosted_this_gp field is a holdover from an earlier design that
was to carry out multiple boost operations in parallel.  It is not required
by the current design, which boosts one task at a time.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:58 -07:00
Paul E. McKenney ddeb75814f rcu: code cleanups in TINY_RCU priority boosting.
Extraneous semicolon, bad comment, and fold INIT_LIST_HEAD() into
list_del() to get list_del_init().

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:58 -07:00
Paul E. McKenney f0a07aeaf8 rcu: Switch to this_cpu() primitives
This removes a couple of lines from invoke_rcu_cpu_kthread(), improving
readability.

Reported-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:57 -07:00
Paul E. McKenney 108aae2233 rcu: Use WARN_ON_ONCE for DEBUG_OBJECTS_RCU_HEAD warnings
Avoid additional multiple-warning confusion in memory-corruption scenarios.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:57 -07:00
Paul E. McKenney 561190e3b3 rcu: mark rcutorture boosting callback as being on-stack
The CONFIG_DEBUG_OBJECTS_RCU_HEAD facility requires that on-stack RCU
callbacks be flagged explicitly to debug-objects using the
init_rcu_head_on_stack() and destroy_rcu_head_on_stack() functions.
This commit applies those functions to the rcutorture code that tests
RCU priority boosting.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:57 -07:00
Mathieu Desnoyers fc2ecf7ec7 rcu: Enable DEBUG_OBJECTS_RCU_HEAD from !PREEMPT
The prohibition of DEBUG_OBJECTS_RCU_HEAD from !PREEMPT was due to the
fixup actions.  So just produce a warning from !PREEMPT.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:57 -07:00
Paul E. McKenney 5ece5bab3e rcu: Add forward-progress diagnostic for per-CPU kthreads
Increment a per-CPU counter on each pass through rcu_cpu_kthread()'s
service loop, and add it to the rcudata trace output.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:57 -07:00
Paul E. McKenney 15ba0ba860 rcu: add grace-period age and more kthread state to tracing
This commit adds the age in jiffies of the current grace period along
with the duration in jiffies of the longest grace period since boot
to the rcu/rcugp debugfs file.  It also adds an additional "O" state
to kthread tracing to differentiate between the kthread waiting due to
having nothing to do on the one hand and waiting due to being on the
wrong CPU on the other hand.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:56 -07:00
Paul E. McKenney a9f4793d89 rcu: fix tracing bug thinko on boost-balk attribution
The rcu_initiate_boost_trace() function mis-attributed refusals to
initiate RCU priority boosting that were in fact due to its not yet
being time to boost.  This patch fixes the faulty comparison.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:56 -07:00
Paul E. McKenney 4a29865689 rcu: make rcutorture version numbers available through debugfs
It is not possible to accurately correlate rcutorture output with that
of debugfs.  This patch therefore adds a debugfs file that prints out
the rcutorture version number, permitting easy correlation.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:56 -07:00
Paul E. McKenney d71df90ead rcu: add tracing for RCU's kthread run states.
Add tracing to help debugging situations when RCU's kthreads are not
running but are supposed to be.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:56 -07:00
Paul E. McKenney 0ac3d136b2 rcu: add callback-queue information to rcudata output
This commit adds an indication of the state of the callback queue using
a string of four characters following the "ql=" integer queue length.
The first character is "N" if there are callbacks that have been
queued that are not yet ready to be handled by the next grace period, or
"." otherwise.  The second character is "R" if there are callbacks queued
that are ready to be handled by the next grace period, or "." otherwise.
The third character is "W" if there are callbacks waiting for the current
grace period, or "." otherwise.  Finally, the fourth character is "D"
if there are callbacks that have been handled by a prior grace period
and are waiting to be invoked, or ".".

Note that callbacks that are in the process of being invoked are
not shown.  These callbacks would have been removed from the rcu_data
structure's list by rcu_do_batch() prior to being executed.  (These
callbacks are also not reflected in the "ql=" total, FWIW.)

Also, document the new callback-queue trace information.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:56 -07:00
Paul E. McKenney 0ea1f2ebeb rcu: Add boosting to TREE_PREEMPT_RCU tracing
Includes total number of tasks boosted, number boosted on behalf of each
of normal and expedited grace periods, and statistics on attempts to
initiate boosting that failed for various reasons.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:55 -07:00
Paul E. McKenney 67b98dba47 rcu: eliminate unused boosting statistics
The n_rcu_torture_boost_allocerror and n_rcu_torture_boost_afferror
statistics are not actually incremented anymore, so eliminate them.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:55 -07:00
Paul E. McKenney 3acf4a9a3d rcu: avoid hammering sched with yet another bound RT kthread
The scheduler does not appear to take kindly to having multiple
real-time threads bound to a CPU that is going offline.  So this
commit is a temporary hack-around to avoid that happening.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:55 -07:00
Paul E. McKenney e3995a25fa rcu: put per-CPU kthread at non-RT priority during CPU hotplug operations
If you are doing CPU hotplug operations, it is best not to have
CPU-bound realtime tasks running CPU-bound on the outgoing CPU.
So this commit makes per-CPU kthreads run at non-realtime priority
during that time.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:55 -07:00
Paul E. McKenney 0f962a5e72 rcu: Force per-rcu_node kthreads off of the outgoing CPU
The scheduler has had some heartburn in the past when too many real-time
kthreads were affinitied to the outgoing CPU.  So, this commit lightens
the load by forcing the per-rcu_node and the boost kthreads off of the
outgoing CPU.  Note that RCU's per-CPU kthread remains on the outgoing
CPU until the bitter end, as it must in order to preserve correctness.

Also avoid disabling hardirqs across calls to set_cpus_allowed_ptr(),
given that this function can block.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05 23:16:55 -07:00
Paul E. McKenney 27f4d28057 rcu: priority boosting for TREE_PREEMPT_RCU
Add priority boosting for TREE_PREEMPT_RCU, similar to that for
TINY_PREEMPT_RCU.  This is enabled by the default-off RCU_BOOST
kernel parameter.  The priority to which to boost preempted
RCU readers is controlled by the RCU_BOOST_PRIO kernel parameter
(defaulting to real-time priority 1) and the time to wait before
boosting the readers who are blocking a given grace period is
controlled by the RCU_BOOST_DELAY kernel parameter (defaulting to
500 milliseconds).

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:55 -07:00
Paul E. McKenney a26ac2455f rcu: move TREE_RCU from softirq to kthread
If RCU priority boosting is to be meaningful, callback invocation must
be boosted in addition to preempted RCU readers.  Otherwise, in presence
of CPU real-time threads, the grace period ends, but the callbacks don't
get invoked.  If the callbacks don't get invoked, the associated memory
doesn't get freed, so the system is still subject to OOM.

But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
moves the callback invocations to a kthread, which can be boosted easily.

Also add comments and properly synchronized all accesses to
rcu_cpu_kthread_task, as suggested by Lai Jiangshan.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:54 -07:00
Paul E. McKenney 12f5f524ca rcu: merge TREE_PREEPT_RCU blocked_tasks[] lists
Combine the current TREE_PREEMPT_RCU ->blocked_tasks[] lists in the
rcu_node structure into a single ->blkd_tasks list with ->gp_tasks
and ->exp_tasks tail pointers.  This is in preparation for RCU priority
boosting, which will add a third dimension to the combinatorial explosion
in the ->blocked_tasks[] case, but simply a third pointer in the new
->blkd_tasks case.

Also update documentation to reflect blocked_tasks[] merge

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:54 -07:00
Paul E. McKenney e59fb3120b rcu: Decrease memory-barrier usage based on semi-formal proof
Commit d09b62d fixed grace-period synchronization, but left some smp_mb()
invocations in rcu_process_callbacks() that are no longer needed, but
sheer paranoia prevented them from being removed.  This commit removes
them and provides a proof of correctness in their absence.  It also adds
a memory barrier to rcu_report_qs_rsp() immediately before the update to
rsp->completed in order to handle the theoretical possibility that the
compiler or CPU might move massive quantities of code into a lock-based
critical section.  This also proves that the sheer paranoia was not
entirely unjustified, at least from a theoretical point of view.

In addition, the old dyntick-idle synchronization depended on the fact
that grace periods were many milliseconds in duration, so that it could
be assumed that no dyntick-idle CPU could reorder a memory reference
across an entire grace period.  Unfortunately for this design, the
addition of expedited grace periods breaks this assumption, which has
the unfortunate side-effect of requiring atomic operations in the
functions that track dyntick-idle state for RCU.  (There is some hope
that the algorithms used in user-level RCU might be applied here, but
some work is required to handle the NMIs that user-space applications
can happily ignore.  For the short term, better safe than sorry.)

This proof assumes that neither compiler nor CPU will allow a lock
acquisition and release to be reordered, as doing so can result in
deadlock.  The proof is as follows:

1.	A given CPU declares a quiescent state under the protection of
	its leaf rcu_node's lock.

2.	If there is more than one level of rcu_node hierarchy, the
	last CPU to declare a quiescent state will also acquire the
	->lock of the next rcu_node up in the hierarchy,  but only
	after releasing the lower level's lock.  The acquisition of this
	lock clearly cannot occur prior to the acquisition of the leaf
	node's lock.

3.	Step 2 repeats until we reach the root rcu_node structure.
	Please note again that only one lock is held at a time through
	this process.  The acquisition of the root rcu_node's ->lock
	must occur after the release of that of the leaf rcu_node.

4.	At this point, we set the ->completed field in the rcu_state
	structure in rcu_report_qs_rsp().  However, if the rcu_node
	hierarchy contains only one rcu_node, then in theory the code
	preceding the quiescent state could leak into the critical
	section.  We therefore precede the update of ->completed with a
	memory barrier.  All CPUs will therefore agree that any updates
	preceding any report of a quiescent state will have happened
	before the update of ->completed.

5.	Regardless of whether a new grace period is needed, rcu_start_gp()
	will propagate the new value of ->completed to all of the leaf
	rcu_node structures, under the protection of each rcu_node's ->lock.
	If a new grace period is needed immediately, this propagation
	will occur in the same critical section that ->completed was
	set in, but courtesy of the memory barrier in #4 above, is still
	seen to follow any pre-quiescent-state activity.

6.	When a given CPU invokes __rcu_process_gp_end(), it becomes
	aware of the end of the old grace period and therefore makes
	any RCU callbacks that were waiting on that grace period eligible
	for invocation.

	If this CPU is the same one that detected the end of the grace
	period, and if there is but a single rcu_node in the hierarchy,
	we will still be in the single critical section.  In this case,
	the memory barrier in step #4 guarantees that all callbacks will
	be seen to execute after each CPU's quiescent state.

	On the other hand, if this is a different CPU, it will acquire
	the leaf rcu_node's ->lock, and will again be serialized after
	each CPU's quiescent state for the old grace period.

On the strength of this proof, this commit therefore removes the memory
barriers from rcu_process_callbacks() and adds one to rcu_report_qs_rsp().
The effect is to reduce the number of memory barriers by one and to
reduce the frequency of execution from about once per scheduling tick
per CPU to once per grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:54 -07:00
Paul E. McKenney a00e0d714f rcu: Remove conditional compilation for RCU CPU stall warnings
The RCU CPU stall warnings can now be controlled using the
rcu_cpu_stall_suppress boot-time parameter or via the same parameter
from sysfs.  There is therefore no longer any reason to have
kernel config parameters for this feature.  This commit therefore
removes the RCU_CPU_STALL_DETECTOR and RCU_CPU_STALL_DETECTOR_RUNNABLE
kernel config parameters.  The RCU_CPU_STALL_TIMEOUT parameter remains
to allow the timeout to be tuned and the RCU_CPU_STALL_VERBOSE parameter
remains to allow task-stall information to be suppressed if desired.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05 23:16:54 -07:00
Ingo Molnar 4d70230bb4 Merge branch 'master' of ssh://master.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into perf/urgent 2011-05-06 08:11:28 +02:00