From mboxrd@z Thu Jan 1 00:00:00 1970 From: Samuel Ortiz Subject: Re: [PATCH -rt] Fix initialization of spinlock in irttp_dup() Date: Tue, 20 Mar 2007 23:50:12 +0200 Message-ID: <20070320215012.GA4089@sortiz.org> References: <20070320192233.GA14543@plexity.net> Reply-To: Samuel Ortiz Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, Andrew Morton , Ingo Molnar , Daniel Walker To: Deepak Saxena Return-path: Received: from smtp23.orange.fr ([80.12.242.50]:56718 "EHLO smtp23.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753913AbXCTVuU (ORCPT ); Tue, 20 Mar 2007 17:50:20 -0400 Content-Disposition: inline In-Reply-To: <20070320192233.GA14543@plexity.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Deepak, On Tue, Mar 20, 2007 at 12:22:33PM -0700, Deepak Saxena wrote: > This was found around the 2.6.10 timeframe when testing with the -rt patch > and I believe is still is an issue. irttp_dup() does a memcpy() of the tsap_cb > structure causing the spinlock protecting various fields in the structure to be > duped. This works OK in the non-RT case but in the RT case we end up with two > mutexes pointing to the same wait_list and leading to an OOPS. Fix is to simply > initialize the spinlock after the memcpy(). This has just made it to the netdev and stable trees. See: http://git.kernel.org/?p=linux/kernel/git/davem/net-2.6.git;a=commit;h=7bb1bbe615de25d955b974cb47d40fa198154bb9 Cheers, Samuel. > Signed-off-by: Deepak Saxena > > diff --git a/net/irda/irttp.c b/net/irda/irttp.c > index a7486b3..df2b2f7 100644 > --- a/net/irda/irttp.c > +++ b/net/irda/irttp.c > @@ -1441,6 +1441,7 @@ struct tsap_cb *irttp_dup(struct tsap_cb > } > /* Dup */ > memcpy(new, orig, sizeof(struct tsap_cb)); > + spin_lock_init(&new->lock); > > /* We don't need the old instance any more */ > spin_unlock_irqrestore(&irttp->tsaps->hb_spinlock, flags); > > > -- > Deepak Saxena - dsaxena@plexity.net - http://www.plexity.net > > In the end, they will not say, "those were dark times," they will ask > "why were their poets silent?" - Bertolt Brecht