make cancel_xxx_work_sync() return a boolean

Change cancel_work_sync() and cancel_delayed_work_sync() to return a boolean
indicating whether the work was actually cancelled.  A zero return value means
that the work was not pending/queued.

Without that kind of change it is not possible to avoid flush_workqueue()
sometimes, see the next patch as an example.

Also, this patch unifies both functions and kills the (unlikely) busy-wait
loop.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 5c89ac6e7f55..ce6badc98f6d 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -148,7 +148,7 @@ extern int keventd_up(void);
 extern void init_workqueues(void);
 int execute_in_process_context(work_func_t fn, struct execute_work *);
 
-extern void cancel_work_sync(struct work_struct *work);
+extern int cancel_work_sync(struct work_struct *work);
 
 /*
  * Kill off a pending schedule_delayed_work().  Note that the work callback
@@ -166,7 +166,7 @@ static inline int cancel_delayed_work(struct delayed_work *work)
         return ret;
 }
 
-extern void cancel_delayed_work_sync(struct delayed_work *work);
+extern int cancel_delayed_work_sync(struct delayed_work *work);
 
 /* Obsolete. use cancel_delayed_work_sync() */
 static inline