Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737Ab2HNWuf (ORCPT ); Tue, 14 Aug 2012 18:50:35 -0400 Received: from mga02.intel.com ([134.134.136.20]:7736 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751863Ab2HNWuc (ORCPT ); Tue, 14 Aug 2012 18:50:32 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.77,769,1336374000"; d="scan'208";a="186459212" From: John Fastabend Subject: [net PATCH v3 3/3] net: netprio: fix cgrp create and write priomap race To: viro@ZenIV.linux.org.uk, nhorman@tuxdriver.com Cc: netdev@vger.kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org, joe@perches.com Date: Tue, 14 Aug 2012 15:34:35 -0700 Message-ID: <20120814223435.3551.62387.stgit@jf-dev1-dcblab> In-Reply-To: <20120814223424.3551.21608.stgit@jf-dev1-dcblab> References: <20120814223424.3551.21608.stgit@jf-dev1-dcblab> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1682 Lines: 58 A race exists where creating cgroups and also updating the priomap may result in losing a priomap update. This is because priomap writers are not protected by rtnl_lock. Move priority writer into rtnl_lock()/rtnl_unlock(). CC: Neil Horman Reported-by: Al Viro Signed-off-by: John Fastabend --- net/core/netprio_cgroup.c | 8 +++----- 1 files changed, 3 insertions(+), 5 deletions(-) diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c index f65dba3..c75e3f9 100644 --- a/net/core/netprio_cgroup.c +++ b/net/core/netprio_cgroup.c @@ -101,12 +101,10 @@ static int write_update_netdev_table(struct net_device *dev) u32 max_len; struct netprio_map *map; - rtnl_lock(); max_len = atomic_read(&max_prioidx) + 1; map = rtnl_dereference(dev->priomap); if (!map || map->priomap_len < max_len) ret = extend_netdev_table(dev, max_len); - rtnl_unlock(); return ret; } @@ -256,17 +254,17 @@ static int write_priomap(struct cgroup *cgrp, struct cftype *cft, if (!dev) goto out_free_devname; + rtnl_lock(); ret = write_update_netdev_table(dev); if (ret < 0) goto out_put_dev; - rcu_read_lock(); - map = rcu_dereference(dev->priomap); + map = rtnl_dereference(dev->priomap); if (map) map->priomap[prioidx] = priority; - rcu_read_unlock(); out_put_dev: + rtnl_unlock(); dev_put(dev); out_free_devname: -- 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/