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SubjectRe: [tip:sched/core] sched: Change wait_for_completion_*_timeout() to return a signed long
On Tue, 11 Jan 2011 16:44:58 -0500 "J. Bruce Fields" <bfields@fieldses.org>
wrote:

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

Yes indeed!
I should have tagged it for Cc:stable@kernel.org in the first place. I had
been meaning to forward it to stable@kernel.org, but you beat me to it!

Thanks,
NeilBrown


>
> --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)
> > {



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