From mboxrd@z Thu Jan 1 00:00:00 1970 From: frank.blaschka@de.ibm.com Subject: [patch 06/10] [PATCH] qeth: suspicious rcu_dereference_check in recovery Date: Tue, 20 Dec 2011 09:56:32 +0100 Message-ID: <20111220085736.122805720@de.ibm.com> References: <20111220085626.924756639@de.ibm.com> Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, Ursula Braun To: davem@davemloft.net Return-path: Received: from e06smtp14.uk.ibm.com ([195.75.94.110]:48963 "EHLO e06smtp14.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752724Ab1LTI6D (ORCPT ); Tue, 20 Dec 2011 03:58:03 -0500 Received: from /spool/local by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 20 Dec 2011 08:57:58 -0000 Content-Disposition: inline; filename=606-qeth-rtnl-lock.diff Sender: netdev-owner@vger.kernel.org List-ID: From: Ursula Braun qeth layer3 recovery invokes its set_multicast_list function, which invokes function __vlan_find_dev_deep requiring rcu_read_lock or rtnl lock. This causes kernel messages: kernel: [ INFO: suspicious rcu_dereference_check() usage. ] kernel: --------------------------------------------------- kernel: net/8021q/vlan_core.c:70 invoked rcu_dereference_check() without protection! kernel: stack backtrace: kernel: CPU: 0 Not tainted 3.1.0 #9 kernel: Process qeth_recover (pid: 2078, task: 000000007e584680, ksp: 000000007e3e3930) kernel: 000000007e3e3d08 000000007e3e3c88 0000000000000002 0000000000000000 kernel: 000000007e3e3d28 000000007e3e3ca0 000000007e3e3ca0 00000000005e77ce kernel: 0000000000000000 0000000000000001 ffffffffffffffff 0000000000000001 kernel: 000000000000000d 000000000000000c 000000007e3e3cf0 0000000000000000 kernel: 0000000000000000 0000000000100a18 000000007e3e3c88 000000007e3e3cc8 kernel: Call Trace: kernel: ([<0000000000100926>] show_trace+0xee/0x144) kernel: [<00000000005d395c>] __vlan_find_dev_deep+0xb0/0x108 kernel: [<00000000004acd3a>] qeth_l3_set_multicast_list+0x976/0xe38 kernel: [<00000000004ae0f4>] __qeth_l3_set_online+0x75c/0x1498 kernel: [<00000000004aefec>] qeth_l3_recover+0xc4/0x1d0 kernel: [<0000000000185372>] kthread+0xa6/0xb0 kernel: [<00000000005ed4c6>] kernel_thread_starter+0x6/0xc kernel: [<00000000005ed4c0>] kernel_thread_starter+0x0/0xc The patch makes sure the rtnl lock is held once qeth recovery invokes its set_multicast_list function. Signed-off-by: Ursula Braun Signed-off-by: Frank Blaschka --- drivers/s390/net/qeth_l3_main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -3492,14 +3492,13 @@ contin: else netif_carrier_off(card->dev); if (recover_flag == CARD_STATE_RECOVER) { + rtnl_lock(); if (recovery_mode) __qeth_l3_open(card->dev); - else { - rtnl_lock(); + else dev_open(card->dev); - rtnl_unlock(); - } qeth_l3_set_multicast_list(card->dev); + rtnl_unlock(); } /* let user_space know that device is online */ kobject_uevent(&gdev->dev.kobj, KOBJ_CHANGE);