Return-Path: Received: from fieldses.org ([174.143.236.118]:53777 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755695Ab0HCVXo (ORCPT ); Tue, 3 Aug 2010 17:23:44 -0400 Date: Tue, 3 Aug 2010 17:22:20 -0400 From: "J. Bruce Fields" To: Trond Myklebust Cc: Jeff Layton , linux-nfs@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH] SUNRPC: prevent task_cleanup running on freed xprt Message-ID: <20100803212220.GI31579@fieldses.org> References: <20100803132453.4fa18444@tlielax.poochiereds.net> <1280860815.9771.25.camel@heimdal.trondhjem.org> <1280861363.12283.2.camel@heimdal.trondhjem.org> Content-Type: text/plain; charset=us-ascii In-Reply-To: <1280861363.12283.2.camel@heimdal.trondhjem.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 From: J. Bruce Fields We saw a report of a NULL dereference in xprt_autoclose: https://bugzilla.redhat.com/show_bug.cgi?id=611938 This appears to be the result of an xprt's task_cleanup running after the xprt is destroyed. Nothing in the current code appears to prevent that. Signed-off-by: J. Bruce Fields --- net/sunrpc/xprt.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) On Tue, Aug 03, 2010 at 02:49:23PM -0400, Trond Myklebust wrote: > Hmm... On the other hand, since xprt_destroy() may get called from > inside the rpciod_workqueue, the wait_on_bit_lock() may end up > deadlocking. > > Nevermind, then. Let's go with the cancel_work_sync(). Here you are--only if you don't have something equivalent already queued up.--b. diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index dcd0132..2a1f664 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1129,6 +1129,7 @@ static void xprt_destroy(struct kref *kref) rpc_destroy_wait_queue(&xprt->sending); rpc_destroy_wait_queue(&xprt->resend); rpc_destroy_wait_queue(&xprt->backlog); + cancel_work_sync(&xprt->task_cleanup); /* * Tear down transport state and free the rpc_xprt */ -- 1.7.0.4