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    SubjectRe: RFC: mutex: hung tasks on SMP platforms with asm-generic/mutex-xchg.h
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    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?


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