From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Tucker Subject: Re: [PATCH 3/3] SUNRPC: svc_xprt_enqueue should not refuse to enqueue 'XPT_DEAD' transports Date: Fri, 02 Jan 2009 15:44:18 -0600 Message-ID: <495E8AB2.8020805@opengridcomputing.com> References: <20081017123207.GA14979@rabbit.intern.cm-ag> <1224484046.23068.14.camel@localhost.localdomain> <1225539927.2221.3.camel@localhost.localdomain> <1225546878.4390.3.camel@heimdal.trondhjem.org> <1227596962.16868.22.camel@localhost.localdomain> <1227619696.7057.19.camel@heimdal.trondhjem.org> <1227620339.9425.99.camel@zakaz.uk.xensource.com> <1227621434.7057.33.camel@heimdal.trondhjem.org> <1227621877.9425.102.camel@zakaz.uk.xensource.com> <1227737539.31008.2.camel@localhost.localdomain> <1228090631.7112.11.camel@heimdal.trondhjem.org> <1228090815.7112.15.camel@heimdal.trondhjem.org> <49491C58.9@opengridcomputing.com> <1229540877.7257.97.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linux-nfs@vger.kernel.org To: Trond Myklebust , "J. Bruce Fields" Return-path: Received: from smtp.opengridcomputing.com ([209.198.142.2]:50811 "EHLO smtp.opengridcomputing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758737AbZABVoV (ORCPT ); Fri, 2 Jan 2009 16:44:21 -0500 In-Reply-To: <1229540877.7257.97.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: Bruce/Trond: This is an alternative to patches 2 and 3 from Trond's fix. I think Trond's fix is correct, but I believe this approach to be simpler. From: Tom Tucker Date: Wed, 31 Dec 2008 17:18:33 -0600 Subject: [PATCH] svc: Clean up deferred requests on transport destruction A race between svc_revisit and svc_delete_xprt can result in deferred requests holding references on a transport that can never be recovered because dead transports are not enqueued for subsequent processing. Check for XPT_DEAD in revisit to clean up completing deferrals on a dead transport and sweep a transport's deferred queue to do the same for queued but unprocessed deferrals. Signed-off-by: Tom Tucker --- net/sunrpc/svc_xprt.c | 20 +++++++++++++++----- 1 files changed, 15 insertions(+), 5 deletions(-) diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index bf5b5cd..92ca5c6 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -837,6 +837,11 @@ static void svc_age_temp_xprts(unsigned long closure) void svc_delete_xprt(struct svc_xprt *xprt) { struct svc_serv *serv = xprt->xpt_server; + struct svc_deferred_req *dr; + + /* Only do this once */ + if (test_and_set_bit(XPT_DEAD, &xprt->xpt_flags)) + return; dprintk("svc: svc_delete_xprt(%p)\n", xprt); xprt->xpt_ops->xpo_detach(xprt); @@ -851,12 +856,16 @@ void svc_delete_xprt(struct svc_xprt *xprt) * while still attached to a queue, the queue itself * is about to be destroyed (in svc_destroy). */ - if (!test_and_set_bit(XPT_DEAD, &xprt->xpt_flags)) { - BUG_ON(atomic_read(&xprt->xpt_ref.refcount) < 2); - if (test_bit(XPT_TEMP, &xprt->xpt_flags)) - serv->sv_tmpcnt--; + if (test_bit(XPT_TEMP, &xprt->xpt_flags)) + serv->sv_tmpcnt--; + + for (dr = svc_deferred_dequeue(xprt); dr; + dr = svc_deferred_dequeue(xprt)) { svc_xprt_put(xprt); + kfree(dr); } + + svc_xprt_put(xprt); spin_unlock_bh(&serv->sv_lock); } @@ -902,7 +911,8 @@ static void svc_revisit(struct cache_deferred_req *dreq, int too_many) container_of(dreq, struct svc_deferred_req, handle); struct svc_xprt *xprt = dr->xprt; - if (too_many) { + if (too_many || test_bit(XPT_DEAD, &xprt->xpt_flags)) { + dprintk("revisit cancelled\n"); svc_xprt_put(xprt); kfree(dr); return;