Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932567AbVLGD2v (ORCPT ); Tue, 6 Dec 2005 22:28:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932247AbVLGD2v (ORCPT ); Tue, 6 Dec 2005 22:28:51 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:33001 "EHLO e3.ny.us.ibm.com") by vger.kernel.org with ESMTP id S932567AbVLGD2u (ORCPT ); Tue, 6 Dec 2005 22:28:50 -0500 Date: Wed, 7 Dec 2005 09:00:25 +0530 From: Ananth N Mavinakayanahalli To: Keshavamurthy Anil S Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, prasanna@in.ibm.com Subject: Re: [PATCH] kprobes: fix race in aggregate kprobe registration Message-ID: <20051207033025.GA2643@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20051206051711.GA3206@in.ibm.com> <20051206131823.A8726@unix-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051206131823.A8726@unix-os.sc.intel.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1849 Lines: 49 On Tue, Dec 06, 2005 at 01:18:24PM -0800, Keshavamurthy Anil S wrote: > 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. Your patch looks better. Andrew, Anil's patch depends on the list.h updates currently in -mm > Signed-off-by: Anil S Keshavamurthy Acked-by: Ananth N Mavinakayanahalli > > 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/