From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Elder Subject: Re: [PATCH 6/8] libceph: avoid dropping con mutex before fault Date: Mon, 30 Jul 2012 19:12:16 -0500 Message-ID: <501722E0.1080203@inktank.com> References: <1343663971-3221-1-git-send-email-sage@inktank.com> <1343663971-3221-7-git-send-email-sage@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-gh0-f174.google.com ([209.85.160.174]:45013 "EHLO mail-gh0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752308Ab2GaAMR (ORCPT ); Mon, 30 Jul 2012 20:12:17 -0400 Received: by ghrr11 with SMTP id r11so5492088ghr.19 for ; Mon, 30 Jul 2012 17:12:16 -0700 (PDT) In-Reply-To: <1343663971-3221-7-git-send-email-sage@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Sage Weil Cc: ceph-devel@vger.kernel.org On 07/30/2012 10:59 AM, Sage Weil wrote: > The ceph_fault() function takes the con mutex, so we should avoid > dropping it before calling it. This fixes a potential race with > another thread calling ceph_con_close(), or _open(), or similar (we > don't reverify con->state after retaking the lock). > > Add annotation so that lockdep realizes we will drop the mutex before > returning. > > Signed-off-by: Sage Weil Looks good. Reviewed-by: Alex Elder > --- > net/ceph/messenger.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c > index feb5a2a..c3b628c 100644 > --- a/net/ceph/messenger.c > +++ b/net/ceph/messenger.c > @@ -2336,7 +2336,6 @@ done_unlocked: > return; > > fault: > - mutex_unlock(&con->mutex); > ceph_fault(con); /* error/fault path */ > goto done_unlocked; > } > @@ -2347,9 +2346,8 @@ fault: > * exponential backoff > */ > static void ceph_fault(struct ceph_connection *con) > + __releases(con->mutex) > { > - mutex_lock(&con->mutex); > - > pr_err("%s%lld %s %s\n", ENTITY_NAME(con->peer_name), > ceph_pr_addr(&con->peer_addr.in_addr), con->error_msg); > dout("fault %p state %lu to peer %s\n", >