From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757903Ab3KMCaZ (ORCPT ); Tue, 12 Nov 2013 21:30:25 -0500 Received: from mail.linux-iscsi.org ([67.23.28.174]:36753 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757561Ab3KMCaM (ORCPT ); Tue, 12 Nov 2013 21:30:12 -0500 From: "Nicholas A. Bellinger" To: target-devel Cc: linux-scsi , linux-kernel , Moussa Ba , Or Gerlitz , Mike Christie , Nicholas Bellinger Subject: [PATCH 1/2] iscsi-target: Fix mutex_trylock usage in iscsit_increment_maxcmdsn Date: Wed, 13 Nov 2013 02:11:42 +0000 Message-Id: <1384308703-10034-2-git-send-email-nab@daterainc.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1384308703-10034-1-git-send-email-nab@daterainc.com> References: <1384308703-10034-1-git-send-email-nab@daterainc.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nicholas Bellinger 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 --- drivers/target/iscsi/iscsi_target_configfs.c | 5 +++++ drivers/target/iscsi/iscsi_target_device.c | 6 +----- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c index 1eec37c..fde3624 100644 --- a/drivers/target/iscsi/iscsi_target_configfs.c +++ b/drivers/target/iscsi/iscsi_target_configfs.c @@ -1790,6 +1790,11 @@ static int lio_queue_status(struct se_cmd *se_cmd) 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; diff --git a/drivers/target/iscsi/iscsi_target_device.c b/drivers/target/iscsi/iscsi_target_device.c index 6c7a510..7087c73 100644 --- a/drivers/target/iscsi/iscsi_target_device.c +++ b/drivers/target/iscsi/iscsi_target_device.c @@ -58,11 +58,7 @@ void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess 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); -- 1.7.10.4