Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030248AbVLFVSj (ORCPT ); Tue, 6 Dec 2005 16:18:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030245AbVLFVSi (ORCPT ); Tue, 6 Dec 2005 16:18:38 -0500 Received: from fmr21.intel.com ([143.183.121.13]:54713 "EHLO scsfmr001.sc.intel.com") by vger.kernel.org with ESMTP id S1030248AbVLFVSh (ORCPT ); Tue, 6 Dec 2005 16:18:37 -0500 Date: Tue, 6 Dec 2005 13:18:24 -0800 From: Keshavamurthy Anil S To: Ananth N Mavinakayanahalli Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, prasanna@in.ibm.com, anil.s.keshavamurthy@intel.com Subject: Re: [PATCH] kprobes: fix race in aggregate kprobe registration Message-ID: <20051206131823.A8726@unix-os.sc.intel.com> Reply-To: Keshavamurthy Anil S References: <20051206051711.GA3206@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20051206051711.GA3206@in.ibm.com>; from ananth@in.ibm.com on Tue, Dec 06, 2005 at 10:47:11AM +0530 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1556 Lines: 41 On Tue, Dec 06, 2005 at 10:47:11AM +0530, Ananth N Mavinakayanahalli wrote: > From: Ananth N Mavinakayanahalli > > When registering multiple kprobes at the same address, we leave a small > window where the kprobe hlist will not contain a reference to the > registered kprobe, leading to potentially, a system crash if the > breakpoint is hit on another processor. > > Patch below changes the order of hlist updation to make sure that there > is always a reference to the kprobe at the location. Hi Ananth, How do you like this patch? Here the old entry will be replace with the new entry automically. Signed-off-by: Anil S Keshavamurthy kernel/kprobes.c | 5 +---- 1 files changed, 1 insertion(+), 4 deletions(-) Index: linux-2.6.15-rc5-mm1/kernel/kprobes.c =================================================================== --- linux-2.6.15-rc5-mm1.orig/kernel/kprobes.c +++ linux-2.6.15-rc5-mm1/kernel/kprobes.c @@ -399,10 +399,7 @@ static inline void add_aggr_kprobe(struc INIT_LIST_HEAD(&ap->list); list_add_rcu(&p->list, &ap->list); - INIT_HLIST_NODE(&ap->hlist); - hlist_del_rcu(&p->hlist); - hlist_add_head_rcu(&ap->hlist, - &kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]); + hlist_replace_rcu(&p->hlist, &ap->hlist); } /* - 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/