Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750748AbWHAVHy (ORCPT ); Tue, 1 Aug 2006 17:07:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750769AbWHAVHy (ORCPT ); Tue, 1 Aug 2006 17:07:54 -0400 Received: from ms-smtp-04.nyroc.rr.com ([24.24.2.58]:27641 "EHLO ms-smtp-04.nyroc.rr.com") by vger.kernel.org with ESMTP id S1750748AbWHAVHx (ORCPT ); Tue, 1 Aug 2006 17:07:53 -0400 Subject: Re: [-rt] Fix race condition and following BUG in PI-futex From: Steven Rostedt To: Darren Hart Cc: Esben Nielsen , Ingo Molnar , Thomas Gleixner , LKML In-Reply-To: <200608011322.53638.dvhltc@us.ibm.com> References: <1154456580.25983.25.camel@localhost.localdomain> <200608011322.53638.dvhltc@us.ibm.com> Content-Type: text/plain Date: Tue, 01 Aug 2006 17:07:36 -0400 Message-Id: <1154466456.30391.12.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1058 Lines: 27 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. -- Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/