Messages in this thread | | | Date | Mon, 13 Aug 2012 10:13:49 +0100 | From | Will Deacon <> | Subject | Re: RFC: mutex: hung tasks on SMP platforms with asm-generic/mutex-xchg.h |
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Hi Peter,
On Mon, Aug 13, 2012 at 09:15:04AM +0100, Peter Zijlstra wrote: > On Thu, 2012-08-09 at 12:57 -0400, Nicolas Pitre wrote: > > > > In other words, I think this should look like this: > > > > diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h > > index 580a6d35c7..44a66c99c8 100644 > > --- a/include/asm-generic/mutex-xchg.h > > +++ b/include/asm-generic/mutex-xchg.h > > @@ -25,8 +25,11 @@ > > static inline void > > __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) > > { > > - if (unlikely(atomic_xchg(count, 0) != 1)) > > - fail_fn(count); > > + if (unlikely(atomic_xchg(count, 0) != 1)) { > > + /* Mark lock contention explicitly */ > > + if (likely(atomic_xchg(count, -1) != 1)) > > + fail_fn(count); > > + } > > } > > OK, I like this.. Thanks guys! Will will you send a final and complete > patch?
I sent one out on Friday but somehow managed to drop you from CC -- sorry about that:
http://thread.gmane.org/gmane.linux.kernel/1341305
Cheers,
Will
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