Oleg Nesterov 8d1f431cbe sched: Fix the racy usage of thread_group_cputimer() in fastpath_timer_check() ...

fastpath_timer_check()->thread_group_cputimer() is racy and
unneeded.

It is racy because another thread can clear ->running before
thread_group_cputimer() takes cputimer->lock. In this case
thread_group_cputimer() will set ->running = true again and call
thread_group_cputime(). But since we do not hold tasklist or
siglock, we can race with fork/exit and copy the wrong results
into cputimer->cputime.

It is unneeded because if ->running == true we can just use
the numbers in cputimer->cputime we already have.

Change fastpath_timer_check() to copy cputimer->cputime into
the local variable under cputimer->lock. We do not re-check
->running under cputimer->lock, run_posix_cpu_timers() does
this check later.

Note: we can add more optimizations on top of this change.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100611180446.GA13025@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2010-06-18 10:46:57 +02:00

..

debug

module: fix kdb's illicit use of struct module_use.

2010-06-05 11:17:36 +09:30

gcov

microblaze: Enable GCOV_PROFILE_ALL

2009-09-21 14:29:21 +02:00

irq

genirq: Clear CPU mask in affinity_hint when none is provided

2010-05-12 11:23:34 +02:00

power

PM / Hibernate: Fix block_io.c printk warning

2010-05-10 23:08:18 +02:00

time

sched: Change nohz idle load balancing logic to push model

2010-06-09 10:34:52 +02:00

trace

sched_clock: Add local_clock() API and improve documentation

2010-06-09 10:34:49 +02:00

.gitignore

…

acct.c

Merge branch 'next' into for-linus

2010-05-18 08:57:00 +10:00

async.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

audit_tree.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

audit_watch.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

audit.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

audit.h

…

auditfilter.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

auditsc.c

audit: preface audit printk with audit

2010-04-05 13:19:45 -07:00

backtracetest.c

…

bounds.c

kbuild: move bounds.h to include/generated

2009-12-12 13:08:14 +01:00

capability.c

sched: Remove remaining USER_SCHED code

2010-04-02 20:12:00 +02:00

cgroup_freezer.c

Freezer / cgroup freezer: Update stale locking comments

2010-05-10 23:18:47 +02:00

cgroup.c

cgroups: alloc_css_id() increments hierarchy depth

2010-06-04 15:21:45 -07:00

compat.c

cpumask: fix compat getaffinity

2010-05-19 11:48:18 -07:00

configs.c

…

cpu.c

sched: adjust when cpu_active and cpuset configurations are updated during cpu on/offlining

2010-06-08 21:40:36 +02:00

cpuset.c

sched: adjust when cpu_active and cpuset configurations are updated during cpu on/offlining

2010-06-08 21:40:36 +02:00

cred.c

umh: creds: kill subprocess_info->cred logic

2010-05-27 09:12:45 -07:00

delayacct.c

…

dma.c

…

early_res.c

x86: Do not free zero sized per cpu areas

2010-03-29 18:55:40 +02:00

elfcore.c

elf coredump: add extended numbering support

2010-03-06 11:26:46 -08:00

exec_domain.c

sys_personality: change sys_personality() to accept "unsigned int" instead of u_long

2010-06-04 15:21:45 -07:00

exit.c

proc: turn signal_struct->count into "int nr_threads"

2010-05-27 09:12:47 -07:00

extable.c

…

fork.c

sched: add hooks for workqueue

2010-06-08 21:40:37 +02:00

freezer.c

…

futex_compat.c

futex: Protect pid lookup in compat code with RCU

2009-12-09 14:22:14 +01:00

futex.c

futex: Handle futex value corruption gracefully

2010-02-03 15:13:22 +01:00

groups.c

security: remove dead hook task_setgroups

2010-04-12 12:19:18 +10:00

hrtimer.c

sched: Change nohz idle load balancing logic to push model

2010-06-09 10:34:52 +02:00

hung_task.c

softlockup: Fix hung_task_check_count sysctl

2009-11-27 06:21:57 +01:00

hw_breakpoint.c

hw_breakpoints: Fix percpu build failure

2010-05-04 08:39:36 +02:00

itimer.c

itimers: Fix racy writes to cpu_itimer fields

2009-11-18 16:32:12 +01:00

kallsyms.c

kdb: core for kgdb back end (2 of 2)

2010-05-20 21:04:21 -05:00

Kconfig.freezer

…

Kconfig.hz

…

Kconfig.locks

mutex: Better control mutex adaptive spinning config

2009-12-03 11:50:11 +01:00

Kconfig.preempt

…

kexec.c

kexec: fix OOPS in crash_kernel_shrink

2010-05-11 17:33:42 -07:00

kfifo.c

kfifo: Don't use integer as NULL pointer

2010-02-16 15:11:08 -08:00

kmod.c

call_usermodehelper: UMH_WAIT_EXEC ignores kernel_thread() failure

2010-05-27 09:12:45 -07:00

kprobes.c

kprobes: Move enable/disable_kprobe() out from debugfs code

2010-05-08 18:08:30 +02:00

ksysfs.c

sysfs: add struct file* to bin_attr callbacks

2010-05-21 09:37:31 -07:00

kthread.c

cpuset: fix the problem that cpuset_mem_spread_node() returns an offline node

2010-03-24 16:31:21 -07:00

latencytop.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

lockdep_internals.h

lockdep: No need to disable preemption in debug atomic ops

2010-05-04 05:38:16 +02:00

lockdep_proc.c

lockstat: Make lockstat counting per cpu

2010-04-06 00:15:37 +02:00

lockdep_states.h

…

lockdep.c

sched_clock: Add local_clock() API and improve documentation

2010-06-09 10:34:49 +02:00

Makefile

Move kernel/kgdb.c to kernel/debug/debug_core.c

2010-05-20 21:04:18 -05:00

module.c

module: fix bne2 "gave up waiting for init of module libcrc32c"

2010-06-05 11:17:37 +09:30

mutex-debug.c

headers: remove sched.h from interrupt.h

2009-10-11 11:20:58 -07:00

mutex-debug.h

locking: Implement new raw_spinlock

2009-12-14 23:55:32 +01:00

mutex.c

mutex: Fix optimistic spinning vs. BKL

2010-05-19 08:18:44 +02:00

mutex.h

…

notifier.c

sched: Use lockdep-based checking on rcu_dereference()

2010-02-25 10:34:26 +01:00

ns_cgroup.c

cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time

2009-09-24 07:20:58 -07:00

nsproxy.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

padata.c

kernel/: convert cpu notifier to return encapsulate errno value

2010-05-27 09:12:48 -07:00

panic.c

panic: call console_verbose() in panic

2010-05-27 09:12:53 -07:00

params.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2010-03-12 16:04:50 -08:00

perf_event.c

Merge commit 'v2.6.35-rc3' into sched/core

2010-06-18 10:46:35 +02:00

pid_namespace.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

pid.c

pids: increase pid_max based on num_possible_cpus

2010-05-27 09:12:51 -07:00

pm_qos_params.c

PM: PM QOS update fix

2010-05-17 00:21:03 +02:00

posix-cpu-timers.c

sched: Fix the racy usage of thread_group_cputimer() in fastpath_timer_check()

2010-06-18 10:46:57 +02:00

posix-timers.c

posix_timer: Fix error path in timer_create

2010-05-27 22:38:15 +02:00

printk.c

printk,kdb: capture printk() when in kdb shell

2010-05-20 21:04:27 -05:00

profile.c

numa: in-kernel profiling: use cpu_to_mem() for per cpu allocations

2010-05-27 09:12:57 -07:00

ptrace.c

ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm

2010-05-27 09:12:44 -07:00

range.c

x86: Change range end to start+size

2010-02-10 17:47:17 -08:00

rcupdate.c

rcu: slim down rcutiny by removing rcu_scheduler_active and friends

2010-05-10 11:08:34 -07:00

rcutiny_plugin.h

rcu: slim down rcutiny by removing rcu_scheduler_active and friends

2010-05-10 11:08:34 -07:00

rcutiny.c

rcu: remove all rcu head initializations, except on_stack initializations

2010-05-11 16:10:47 -07:00

rcutorture.c

sched_clock: Add local_clock() API and improve documentation

2010-06-09 10:34:49 +02:00

rcutree_plugin.h

rcu: remove all rcu head initializations, except on_stack initializations

2010-05-11 16:10:47 -07:00

rcutree_trace.c

rcu: reduce the number of spurious RCU_SOFTIRQ invocations

2010-05-10 11:08:35 -07:00

rcutree.c

rcu: remove all rcu head initializations, except on_stack initializations

2010-05-11 16:10:47 -07:00

rcutree.h

rcu: reduce the number of spurious RCU_SOFTIRQ invocations

2010-05-10 11:08:35 -07:00

relay.c

kernel/: convert cpu notifier to return encapsulate errno value

2010-05-27 09:12:48 -07:00

res_counter.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

resource.c

resource: shared I/O region support

2010-05-11 12:01:10 -07:00

rtmutex_common.h

…

rtmutex-debug.c

sched: Convert pi_lock to raw_spinlock

2009-12-14 23:55:33 +01:00

rtmutex-debug.h

…

rtmutex-tester.c

…

rtmutex.c

rtmutes: Convert rtmutex.lock to raw_spinlock

2009-12-14 23:55:33 +01:00

rtmutex.h

…

rwsem.c

…

sched_clock.c

sched_clock: Add local_clock() API and improve documentation

2010-06-09 10:34:49 +02:00

sched_cpupri.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

sched_cpupri.h

sched: Convert cpupri lock to raw_spinlock

2009-12-14 23:55:33 +01:00

sched_debug.c

proc_sched_show_task(): use get_nr_threads()

2010-05-27 09:12:47 -07:00

sched_fair.c

sched: Fix comments to make them DocBook happy

2010-06-18 10:46:55 +02:00

sched_features.h

sched: Remove ASYM_GRAN feature

2010-03-11 18:32:53 +01:00

sched_idletask.c

sched: Cure load average vs NO_HZ woes

2010-04-23 11:02:02 +02:00

sched_rt.c

sched: task_tick_rt: Remove the obsolete ->signal != NULL check

2010-06-18 10:46:56 +02:00

sched_stats.h

sched: Remove the obsolete exit_state/signal hacks

2010-06-18 10:46:56 +02:00

sched.c

sched: __sched_setscheduler: Read the RLIMIT_RTPRIO value lockless

2010-06-18 10:46:55 +02:00

seccomp.c

…

semaphore.c

…

signal.c

exit: change zap_other_threads() to count sub-threads

2010-05-27 09:12:46 -07:00

slow-work-debugfs.c

SLOW_WORK: Move slow_work's proc file to debugfs

2009-12-01 08:20:31 -08:00

slow-work.c

slow-work: use get_ref wrapper instead of directly calling get_ref

2010-03-29 09:13:30 -07:00

slow-work.h

SLOW_WORK: CONFIG_SLOW_WORK_PROC should be CONFIG_SLOW_WORK_DEBUG

2010-03-29 09:14:47 -07:00

smp.c

kernel/: convert cpu notifier to return encapsulate errno value

2010-05-27 09:12:48 -07:00

softirq.c

kernel/: fix BUG_ON checks for cpu notifier callbacks direct call

2010-06-04 15:21:45 -07:00

softlockup.c

softlockup: Stop spurious softlockup messages due to overflow

2010-03-21 19:30:13 +01:00

spinlock.c

locking: Cleanup the name space completely

2009-12-14 23:55:33 +01:00

srcu.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

stacktrace.c

…

stop_machine.c

sched: Make sure timers have migrated before killing the migration_thread

2010-05-31 08:37:44 +02:00

sys_ni.c

Add generic sys_ipc wrapper

2010-03-12 15:52:32 -08:00

sys.c

kmod: add init function to usermodehelper

2010-05-27 09:12:44 -07:00

sysctl_binary.c

sysctl: don't use own implementation of hex_to_bin()

2010-05-25 08:07:05 -07:00

sysctl_check.c

ipv4 05/05: add sysctl to accept packets with local source addresses

2009-12-03 12:14:38 -08:00

sysctl.c

pipe: change /proc/sys/fs/pipe-max-pages to byte sized interface

2010-06-03 14:54:39 +02:00

taskstats.c

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30 22:02:32 +09:00

test_kprobes.c

…

time.c

timekeeping: Fix timezone update

2010-05-24 11:50:38 +02:00

timeconst.pl

…

timer.c

sched: Change nohz idle load balancing logic to push model

2010-06-09 10:34:52 +02:00

tracepoint.c

tracing: Let tracepoints have data passed to tracepoint callbacks

2010-05-14 09:50:34 -04:00

tsacct.c

mm: clean up mm_counter

2010-03-06 11:26:23 -08:00

uid16.c

headers: utsname.h redux

2009-09-23 18:13:10 -07:00

up.c

…

user_namespace.c

kref: remove kref_set

2010-05-21 09:37:29 -07:00

user-return-notifier.c

core: Clean up user return notifers use of per_cpu

2009-12-02 10:22:59 +01:00

user.c

sched: Remove a stale comment

2010-05-10 08:48:39 +02:00

utsname_sysctl.c

sysctl kernel: Remove binary sysctl logic

2009-11-12 02:04:55 -08:00

utsname.c

…

wait.c

…

workqueue_sched.h

sched: add hooks for workqueue

2010-06-08 21:40:37 +02:00

workqueue.c

kernel/: convert cpu notifier to return encapsulate errno value

2010-05-27 09:12:48 -07:00