Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | Re: [PATCH] Introduce down_try() so we can move away from down_trylock() | Date | Tue, 29 Jul 2008 23:01:17 +1000 |
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On Tuesday 29 July 2008 10:27:15 Paul Menage wrote: > On Mon, Jul 28, 2008 at 5:15 PM, Rusty Russell <rusty@rustcorp.com.au> wrote: > > +/** > > + * down_try - try to down a semaphore, but don't block > > + * @sem: the semaphore > > Is there a reason to avoid using a return type of "bool" for this?
Probably, but not a good one.
This incorporates Andrew's whitespace fix as well (ie: introduce-down_try-so-we-can-move-away-from-down_trylock.patch and introduce-down_try-so-we-can-move-away-from-down_trylock-checkpatch-fixes.patch)
Introduce down_try()
I planned on removing the much-disliked down_trylock() (with its backwards return codes) in 2.6.27, but it's creating something of a logjam with other patches in -mm and linux-next.
Andrew suggested introducing "down_try" as a wrapper now, to make the transition easier.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Stephen Rothwell <sfr@canb.auug.org.au> --- include/linux/semaphore.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff -r 92664ae4130b include/linux/semaphore.h --- a/include/linux/semaphore.h Wed May 21 14:54:40 2008 +1000 +++ b/include/linux/semaphore.h Wed May 21 15:07:31 2008 +1000 @@ -48,4 +48,18 @@ extern int __must_check down_timeout(str extern int __must_check down_timeout(struct semaphore *sem, long jiffies); extern void up(struct semaphore *sem); +/** + * down_try - try to down a semaphore, but don't block + * @sem: the semaphore + * + * This is equivalent to down_trylock(), but has the same return codes as + * spin_trylock and mutex_trylock: 1 if semaphore acquired, 0 if not. + * + * down_trylock() with its confusing return codes will be deprecated + * soon. It will not be missed. + */ +static inline bool __must_check down_try(struct semaphore *sem) +{ + return !down_trylock(sem); +} #endif /* __LINUX_SEMAPHORE_H */
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