sched: Change wait_for_completion_*_timeout() to return a signed long

wait_for_completion_*_timeout() can return:

   0: if the wait timed out
 -ve: if the wait was interrupted
 +ve: if the completion was completed.

As they currently return an 'unsigned long', the last two cases
are not easily distinguished which can easily result in buggy
code, as is the case for the recently added
wait_for_completion_interruptible_timeout() call in
net/sunrpc/cache.c

So change them both to return 'long'.  As MAX_SCHEDULE_TIMEOUT
is LONG_MAX, a large +ve return value should never overflow.

Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: J.  Bruce Fields <bfields@fieldses.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110105125016.64ccab0e@notabene.brown>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/completion.h b/include/linux/completion.h
index 36d57f74cd01c6c126ee2f7c2ea2c98f66868b2f..51494e6b55487f30496c8870165dd75f8ba4c7b1 100644 (file)
--- a/include/linux/completion.h
+++ b/include/linux/completion.h
@@ -81,10 +81,10 @@ extern int wait_for_completion_interruptible(struct completion *x);
 extern int wait_for_completion_killable(struct completion *x);
 extern unsigned long wait_for_completion_timeout(struct completion *x,
                                                   unsigned long timeout);
-extern unsigned long wait_for_completion_interruptible_timeout(
-                       struct completion *x, unsigned long timeout);
-extern unsigned long wait_for_completion_killable_timeout(
-                       struct completion *x, unsigned long timeout);
+extern long wait_for_completion_interruptible_timeout(
+       struct completion *x, unsigned long timeout);
+extern long wait_for_completion_killable_timeout(
+       struct completion *x, unsigned long timeout);
 extern bool try_wait_for_completion(struct completion *x);
 extern bool completion_done(struct completion *x);
 

diff --git a/kernel/sched.c b/kernel/sched.c
index f2f914e0c47c87ac6aa4a326d5c61d3c25bc2155..114a0deb2b01d2083d26cbcfcab3f6e1c844b8f6 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4395,7 +4395,7 @@ EXPORT_SYMBOL(wait_for_completion_interruptible);
  * This waits for either a completion of a specific task to be signaled or for a
  * specified timeout to expire. It is interruptible. The timeout is in jiffies.
  */
-unsigned long __sched
+long __sched
 wait_for_completion_interruptible_timeout(struct completion *x,
                                          unsigned long timeout)
 {
@@ -4428,7 +4428,7 @@ EXPORT_SYMBOL(wait_for_completion_killable);
  * signaled or for a specified timeout to expire. It can be
  * interrupted by a kill signal. The timeout is in jiffies.
  */
-unsigned long __sched
+long __sched
 wait_for_completion_killable_timeout(struct completion *x,
                                     unsigned long timeout)
 {