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    SubjectRe: [PATCH] bug in futex unqueue_me

    * Christian Borntraeger <> wrote:

    > On Sunday 30 July 2006 08:38, Ingo Molnar wrote:
    > > interesting, how is this possible? We do a spin_lock(lock_ptr), and
    > > taking a spinlock is an implicit barrier(). So gcc must not delay
    > > evaluating lock_ptr to inside the critical section. And as far as i can
    > > see the s390 spinlock implementation goes through an 'asm volatile'
    > > piece of code, which is a barrier already. So how could this have
    > > happened?
    > spin_lock is a barrier, but isnt the barrierness too late here? The
    > compiler reloads the value of lock_ptr after the "if(lock_ptr)" and
    > *before* calling spin_lock(lock_ptr):

    ah, indeed. So your patch is a real fix. Thanks,

    Acked-by: Ingo Molnar <>

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