+ make-cancel_rearming_delayed_work-reliable-fix.patch added to -mm tree

+ make-cancel_rearming_delayed_work-reliable-fix.patch added to -mm tree

[akpm]

The patch titled
     make-cancel_rearming_delayed_work-reliable fix
has been added to the -mm tree.  Its filename is
     make-cancel_rearming_delayed_work-reliable-fix.patch

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: make-cancel_rearming_delayed_work-reliable fix
From: Oleg Nesterov <oleg@tv-sign.ru>

Add cpu-relax() into spinloops, and a comments update.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/workqueue.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff -puN kernel/workqueue.c~make-cancel_rearming_delayed_work-reliable-fix kernel/workqueue.c
--- a/kernel/workqueue.c~make-cancel_rearming_delayed_work-reliable-fix
+++ a/kernel/workqueue.c
@@ -477,13 +477,16 @@ static void wait_on_work(struct work_str
  * case it only guarantees that work->func() has completed on the last queued
  * workqueue.
  *
+ * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not
+ * pending, otherwise it goes into a busy-wait loop until the timer expires.
+ *
  * The caller must ensure that workqueue_struct on which this work was last
  * queued can't be destroyed before this function returns.
  */
 void cancel_work_sync(struct work_struct *work)
 {
 	while (!try_to_grab_pending(work))
-		;
+		cpu_relax();
 	wait_on_work(work);
 	work_clear_pending(work);
 }
@@ -500,7 +503,7 @@ void cancel_rearming_delayed_work(struct
 {
 	while (!del_timer(&dwork->timer) &&
 	       !try_to_grab_pending(&dwork->work))
-		;
+		cpu_relax();
 	wait_on_work(&dwork->work);
 	work_clear_pending(&dwork->work);
 }
_

Patches currently in -mm which might be from oleg@tv-sign.ru are

origin.patch
fix-refrigerator-vs-thaw_process-race.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
allow-access-to-proc-pid-fd-after-setuid.patch
freezer-task-exit_state-should-be-treated-as-bolean.patch
softlockup-trivial-s-99-max_rt_prio.patch
merge-sys_clone-sys_unshare-nsproxy-and-namespace.patch
fix-race-between-proc_get_inode-and-remove_proc_entry.patch
getrusage-fill-ru_inblock-and-ru_oublock-fields-if-possible.patch
futex-restartable-futex_wait.patch
add-support-for-deferrable-timers-respun.patch
add-a-new-deferrable-delayed-work-init.patch
reimplement-flush_workqueue.patch
implement-flush_work.patch
flush_workqueue-use-preempt_disable-to-hold-off-cpu-hotplug.patch
flush_cpu_workqueue-dont-flush-an-empty-worklist.patch
aio-use-flush_work.patch
kblockd-use-flush_work.patch
relayfs-use-flush_keventd_work.patch
tg3-use-flush_keventd_work.patch
e1000-use-flush_keventd_work.patch
libata-use-flush_work.patch
phy-use-flush_work.patch
call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed.patch
slab-use-cpu_lock_.patch
workqueue-fix-freezeable-workqueues-implementation.patch
workqueue-fix-flush_workqueue-vs-cpu_dead-race.patch
workqueue-dont-clear-cwq-thread-until-it-exits.patch
workqueue-dont-migrate-pending-works-from-the-dead-cpu.patch
workqueue-kill-run_scheduled_work.patch
workqueue-dont-save-interrupts-in-run_workqueue.patch
workqueue-make-cancel_rearming_delayed_workqueue-work-on-idle-dwork.patch
workqueue-introduce-cpu_singlethread_map.patch
workqueue-introduce-workqueue_struct-singlethread.patch
workqueue-make-init_workqueues-__init.patch
workqueues-shift-kthread_bind-from-cpu_up_prepare-to-cpu_online.patch
make-queue_delayed_work-friendly-to-flush_fork.patch
unify-queue_delayed_work-and-queue_delayed_work_on.patch
workqueue-introduce-wq_per_cpu-helper.patch
make-cancel_rearming_delayed_work-work-on-any-workqueue-not-just-keventd_wq.patch
ipvs-flush-defense_work-before-module-unload.patch
workqueue-kill-noautorel-works.patch
worker_thread-dont-play-with-signals.patch
worker_thread-fix-racy-try_to_freeze-usage.patch
zap_other_threads-remove-unneeded-exit_signal-change.patch
slab-shutdown-cache_reaper-when-cpu-goes-down.patch
unify-flush_work-flush_work_keventd-and-rename-it-to-cancel_work_sync.patch
____call_usermodehelper-dont-flush_signals.patch
freezer-read-pf_borrowed_mm-in-a-nonracy-way.patch
freezer-close-theoretical-race-between-refrigerator-and-thaw_tasks.patch
freezer-remove-pf_nofreeze-from-rcutorture-thread.patch
freezer-remove-pf_nofreeze-from-bluetooth-threads.patch
freezer-add-try_to_freeze-calls-to-all-kernel-threads.patch
freezer-fix-vfork-problem.patch
freezer-take-kernel_execve-into-consideration.patch
kthread-dont-depend-on-work-queues-take-2.patch
change-reparent_to_init-to-reparent_to_kthreadd.patch
nlmclnt_recovery-dont-use-clone_sighand.patch
usbatm_heavy_init-dont-use-clone_sighand.patch
wait_for_helper-remove-unneeded-do_sigaction.patch
worker_thread-dont-play-with-sigchld-and-numa-policy.patch
change-kernel-threads-to-ignore-signals-instead-of-blocking-them.patch
fix-kthread_create-vs-freezer-theoretical-race.patch
fix-pf_nofreeze-and-freezeable-race-2.patch
freezer-document-task_lock-in-thaw_process.patch
move-frozen_process-to-kernel-power-processc.patch
remvoe-kthread_bind-call-from-_cpu_down.patch
separate-freezer-from-pm-code-rev-2.patch
introduce-freezer-flags-rev-2.patch
make-cancel_rearming_delayed_work-reliable.patch
make-cancel_rearming_delayed_work-reliable-spelling.patch
make-cancel_rearming_delayed_work-reliable-fix.patch
dont-init-pgrp-and-__session-in-init_signals.patch
add-suspend-related-notifications-for-cpu-hotplug-cleanup.patch