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Subject[GIT PULL] workqueue changes for v3.14-rc1
Hello, Linus.

Just one patch to add destroy_work_on_stack() annotations to help
debugobj debugging. The change is almost trivial but unfortunately
causes the following merge conflict.

long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
{
struct work_for_cpu wfc = { .fn = fn, .arg = arg };

INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
schedule_work_on(cpu, &wfc.work);
<<<<<<< HEAD
flush_work(&wfc.work);
=======

/*
* The work item is on-stack and can't lead to deadlock through
* flushing. Use __flush_work() to avoid spurious lockdep warnings
* when work_on_cpu()s are nested.
*/
__flush_work(&wfc.work);

destroy_work_on_stack(&wfc.work);
>>>>>>> 440a11360326044a9addf1c652a0364aad0be90c
return wfc.ret;
}

The conflict is between the following two commits.

* master 12997d1a999c ("Revert "workqueue: allow work_on_cpu() to be called recursively"")
* wq/for-3.14 440a11360326 ("workqueue: Calling destroy_work_on_stack() to pair with INIT_WORK_ONSTACK()")

The former updated work_on_cpu() to drop __flush_work() change to
allow recursive work_on_cpu() usage which no longer was necessary
after PCI update. The latter added destroy_work_on_stack() call to
the function thus causing context conflict. It can be easily resolved
by adding destroy_work_on_stack() to the version in master.

long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
{
struct work_for_cpu wfc = { .fn = fn, .arg = arg };

INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
schedule_work_on(cpu, &wfc.work);
flush_work(&wfc.work);
destroy_work_on_stack(&wfc.work);
return wfc.ret;
}

The merge is also available in the test-merge-3.14 branch of wq tree.

The changes are available in the following git branch.

git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-3.14

for you to fetch changes up to 440a11360326044a9addf1c652a0364aad0be90c:

workqueue: Calling destroy_work_on_stack() to pair with INIT_WORK_ONSTACK() (2014-01-11 22:26:33 -0500)

Thanks.
----------------------------------------------------------------
Chuansheng Liu (1):
workqueue: Calling destroy_work_on_stack() to pair with INIT_WORK_ONSTACK()

kernel/workqueue.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 987293d..00df112 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4776,6 +4776,7 @@ static int workqueue_cpu_down_callback(struct notifier_block *nfb,

/* wait for per-cpu unbinding to finish */
flush_work(&unbind_work);
+ destroy_work_on_stack(&unbind_work);
break;
}
return NOTIFY_OK;
@@ -4822,6 +4823,7 @@ long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
*/
__flush_work(&wfc.work);

+ destroy_work_on_stack(&wfc.work);
return wfc.ret;
}
EXPORT_SYMBOL_GPL(work_on_cpu);

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