Messages in this thread | | | Date | Tue, 29 Jul 2008 09:21:02 -0700 | From | Randy Dunlap <> | Subject | Re: [PATCH] Introduce down_try() so we can move away from down_trylock() |
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On Tue, 29 Jul 2008 23:01:17 +1000 Rusty Russell wrote:
> 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.
Hi Rusty,
Will you also be making updates to Documentation/DocBook/kernel-locking.tmpl ?
> 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 */
--- ~Randy Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA http://linuxplumbersconf.org/
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