Re: [BUG] futex_unlock_pi() hurts my brain and may causeapplication deadlock

From: Steven Rostedt
Date: Wed May 30 2007 - 21:31:01 EST


On Wed, 2007-05-30 at 17:49 -0700, john stultz wrote:

> ...
> retry_locked:
> /*
> * To avoid races, try to do the TID -> 0 atomic transition
> * again. If it succeeds then we can return without waking
> * anyone else up:
> */
> if (!(uval & FUTEX_OWNER_DIED)) {
> pagefault_disable();
> uval = futex_atomic_cmpxchg_inatomic(uaddr, current->pid, 0);
> pagefault_enable();
> }

My question is to all the futex gurus out there.

This code is in futex_unlock_pi. Can the owner of the mutex really die?
Isn't the owner the one doing the unlock?

-- Steve


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