From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932738AbcECAOi (ORCPT ); Mon, 2 May 2016 20:14:38 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59585 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932605AbcECAMr (ORCPT ); Mon, 2 May 2016 20:12:47 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , "J. Bruce Fields" Subject: [PATCH 3.14 37/37] sunrpc/cache: drop reference when sunrpc_cache_pipe_upcall() detects a race Date: Mon, 2 May 2016 17:12:26 -0700 Message-Id: <20160503000424.754358710@linuxfoundation.org> X-Mailer: git-send-email 2.8.2 In-Reply-To: <20160503000423.577563140@linuxfoundation.org> References: <20160503000423.577563140@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit a6ab1e8126d205238defbb55d23661a3a5c6a0d8 upstream. sunrpc_cache_pipe_upcall() can detect a race if CACHE_PENDING is no longer set. In this case it aborts the queuing of the upcall. However it has already taken a new counted reference on "h" and doesn't "put" it, even though it frees the data structure holding the reference. So let's delay the "cache_get" until we know we need it. Fixes: f9e1aedc6c79 ("sunrpc/cache: remove races with queuing an upcall.") Signed-off-by: NeilBrown Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/cache.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -1187,14 +1187,14 @@ int sunrpc_cache_pipe_upcall(struct cach } crq->q.reader = 0; - crq->item = cache_get(h); crq->buf = buf; crq->len = 0; crq->readers = 0; spin_lock(&queue_lock); - if (test_bit(CACHE_PENDING, &h->flags)) + if (test_bit(CACHE_PENDING, &h->flags)) { + crq->item = cache_get(h); list_add_tail(&crq->q.list, &detail->queue); - else + } else /* Lost a race, no longer PENDING, so don't enqueue */ ret = -EAGAIN; spin_unlock(&queue_lock);