From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756603Ab3LBVHI (ORCPT ); Mon, 2 Dec 2013 16:07:08 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38531 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754001Ab3LBTNO (ORCPT ); Mon, 2 Dec 2013 14:13:14 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Moussa Ba , Nicholas Bellinger Subject: [PATCH 3.10 048/173] iscsi-target: Fix mutex_trylock usage in iscsit_increment_maxcmdsn Date: Mon, 2 Dec 2013 11:10:31 -0800 Message-Id: <20131202191148.165675508@linuxfoundation.org> X-Mailer: git-send-email 1.8.4.3.gca3854a In-Reply-To: <20131202191142.873808297@linuxfoundation.org> References: <20131202191142.873808297@linuxfoundation.org> User-Agent: quilt/0.60-8.1.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Bellinger commit 5e8e6b4b3adebf01a9d97056cbbfd8c44330df99 upstream. This patch fixes a >= v3.10 regression bug with mutex_trylock() usage within iscsit_increment_maxcmdsn(), that was originally added to allow for a special case where ->cmdsn_mutex was already held from the iscsit_execute_cmd() exception path for ib_isert. When !mutex_trylock() was occuring under contention during normal RX/TX process context codepaths, the bug was manifesting itself as the following protocol error: Received CmdSN: 0x000fcbb7 is greater than MaxCmdSN: 0x000fcbb6, protocol error. Received CmdSN: 0x000fcbb8 is greater than MaxCmdSN: 0x000fcbb6, protocol error. This patch simply avoids the direct ib_isert callback in lio_queue_status() for the special iscsi_execute_cmd() exception cases, that allows the problematic mutex_trylock() usage in iscsit_increment_maxcmdsn() to go away. Reported-by: Moussa Ba Tested-by: Moussa Ba Signed-off-by: Nicholas Bellinger Signed-off-by: Greg Kroah-Hartman --- drivers/target/iscsi/iscsi_target_configfs.c | 5 +++++ drivers/target/iscsi/iscsi_target_device.c | 6 +----- 2 files changed, 6 insertions(+), 5 deletions(-) --- a/drivers/target/iscsi/iscsi_target_configfs.c +++ b/drivers/target/iscsi/iscsi_target_configfs.c @@ -1650,6 +1650,11 @@ static int lio_queue_status(struct se_cm struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd); cmd->i_state = ISTATE_SEND_STATUS; + + if (cmd->se_cmd.scsi_status || cmd->sense_reason) { + iscsit_add_cmd_to_response_queue(cmd, cmd->conn, cmd->i_state); + return 0; + } cmd->conn->conn_transport->iscsit_queue_status(cmd->conn, cmd); return 0; --- a/drivers/target/iscsi/iscsi_target_device.c +++ b/drivers/target/iscsi/iscsi_target_device.c @@ -60,11 +60,7 @@ void iscsit_increment_maxcmdsn(struct is cmd->maxcmdsn_inc = 1; - if (!mutex_trylock(&sess->cmdsn_mutex)) { - sess->max_cmd_sn += 1; - pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn); - return; - } + mutex_lock(&sess->cmdsn_mutex); sess->max_cmd_sn += 1; pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn); mutex_unlock(&sess->cmdsn_mutex);