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authorOleg Nesterov <oleg@tv-sign.ru>2008-07-25 12:47:49 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 21:53:40 +0400
commitdb700897224b5ebdf852f2d38920ce428940d059 (patch)
tree98f0052929e79b35393352addde70fa5e97b8dee /include/linux
parent1a4d9b0aa0d3c50314e57525a5e5ec2cfc48b4c8 (diff)
downloadlinux-db700897224b5ebdf852f2d38920ce428940d059.tar.xz
workqueues: implement flush_work()
Most of users of flush_workqueue() can be changed to use cancel_work_sync(), but sometimes we really need to wait for the completion and cancelling is not an option. schedule_on_each_cpu() is good example. Add the new helper, flush_work(work), which waits for the completion of the specific work_struct. More precisely, it "flushes" the result of of the last queue_work() which is visible to the caller. For example, this code queue_work(wq, work); /* WINDOW */ queue_work(wq, work); flush_work(work); doesn't necessary work "as expected". What can happen in the WINDOW above is - wq starts the execution of work->func() - the caller migrates to another CPU now, after the 2nd queue_work() this work is active on the previous CPU, and at the same time it is queued on another. In this case flush_work(work) may return before the first work->func() completes. It is trivial to add another helper int flush_work_sync(struct work_struct *work) { return flush_work(work) || wait_on_work(work); } which works "more correctly", but it has to iterate over all CPUs and thus it much slower than flush_work(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Max Krasnyansky <maxk@qualcomm.com> Acked-by: Jarek Poplawski <jarkao2@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/workqueue.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 14d47120682b..5c158c477ac7 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -201,6 +201,8 @@ extern int keventd_up(void);
extern void init_workqueues(void);
int execute_in_process_context(work_func_t fn, struct execute_work *);
+extern int flush_work(struct work_struct *work);
+
extern int cancel_work_sync(struct work_struct *work);
/*