Re: [-rt] Fix race condition and following BUG in PI-futex

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On Tue, 1 Aug 2006, Steven Rostedt wrote:

On Tue, 2006-08-01 at 13:22 -0700, Darren Hart wrote:


  	list_del_init(&pi_state->owner->pi_state_list);
  	list_add(&pi_state->list, &new_owner->pi_state_list);
  	pi_state->owner = new_owner;
+	atomic_inc(&pi_state->refcount);

There really needs to be a get_pi_state() or some variant. Having to do
a manual atomic_inc is very dangerous.

I understand the need to grab the wait_lock in order to serialize
rt_mutex_next_owner(), but why the addition of of the atomic_inc() and the
free_pi_state() ?  And if we do need them, shouldn't we place them around the
use of the pi_state, rather than just before the unlock calls?

Hmm, is the inc really needed?  The hb->lock is held through this and
the pi_state can't go away while that lock is held.

I was going to ask about that... If you say so they can go. I just added the inc/dec to be sure.

Esben


-- Steve


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