Re: [-rt] Fix race condition and following BUG in PI-futex
From: Steven Rostedt
Date: Tue Aug 01 2006 - 17:05:42 EST
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.
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