Re: [tip:sched/core] sched: Change wait_for_completion_*_timeout() to return a signed long

["J. Bruce Fields" <bfields@fieldses.org>]

Doesn't this belong in 2.6.37.y as well?

--b.

On Wed, Jan 05, 2011 at 02:07:12PM +0000, tip-bot for NeilBrown wrote:
> Commit-ID:  6bf4123760a5aece6e4829ce90b70b6ffd751d65
> Gitweb:     http://git.kernel.org/tip/6bf4123760a5aece6e4829ce90b70b6ffd751d65
> Author:     NeilBrown <neilb@suse.de>
> AuthorDate: Wed, 5 Jan 2011 12:50:16 +1100
> Committer:  Ingo Molnar <mingo@elte.hu>
> CommitDate: Wed, 5 Jan 2011 14:15:50 +0100
> 
> 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>
> ---
>  include/linux/completion.h |    8 ++++----
>  kernel/sched.c             |    4 ++--
>  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/completion.h b/include/linux/completion.h
> index 36d57f7..51494e6 100644
> --- 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 f2f914e..114a0de 100644
> --- 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)
>  {