From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934632AbdERLCG (ORCPT ); Thu, 18 May 2017 07:02:06 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:51788 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934534AbdERLBw (ORCPT ); Thu, 18 May 2017 07:01:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gary Guo , Nicholas Bellinger Subject: [PATCH 4.4 05/56] iscsi-target: Set session_fall_back_to_erl0 when forcing reinstatement Date: Thu, 18 May 2017 12:48:22 +0200 Message-Id: <20170518104840.609960885@linuxfoundation.org> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170518104840.395932131@linuxfoundation.org> References: <20170518104840.395932131@linuxfoundation.org> User-Agent: quilt/0.65 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 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Bellinger commit 197b806ae5db60c6f609d74da04ddb62ea5e1b00 upstream. While testing modification of per se_node_acl queue_depth forcing session reinstatement via lio_target_nacl_cmdsn_depth_store() -> core_tpg_set_initiator_node_queue_depth(), a hung task bug triggered when changing cmdsn_depth invoked session reinstatement while an iscsi login was already waiting for session reinstatement to complete. This can happen when an outstanding se_cmd descriptor is taking a long time to complete, and session reinstatement from iscsi login or cmdsn_depth change occurs concurrently. To address this bug, explicitly set session_fall_back_to_erl0 = 1 when forcing session reinstatement, so session reinstatement is not attempted if an active session is already being shutdown. This patch has been tested with two scenarios. The first when iscsi login is blocked waiting for iscsi session reinstatement to complete followed by queue_depth change via configfs, and second when queue_depth change via configfs us blocked followed by a iscsi login driven session reinstatement. Note this patch depends on commit d36ad77f702 to handle multiple sessions per se_node_acl when changing cmdsn_depth, and for pre v4.5 kernels will need to be included for stable as well. Reported-by: Gary Guo Tested-by: Gary Guo Cc: Gary Guo Signed-off-by: Nicholas Bellinger Signed-off-by: Greg Kroah-Hartman --- drivers/target/iscsi/iscsi_target.c | 1 + drivers/target/iscsi/iscsi_target_configfs.c | 1 + drivers/target/iscsi/iscsi_target_login.c | 1 + 3 files changed, 3 insertions(+) --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -4821,6 +4821,7 @@ int iscsit_release_sessions_for_tpg(stru continue; } atomic_set(&sess->session_reinstatement, 1); + atomic_set(&sess->session_fall_back_to_erl0, 1); spin_unlock(&sess->conn_lock); list_move_tail(&se_sess->sess_list, &free_list); --- a/drivers/target/iscsi/iscsi_target_configfs.c +++ b/drivers/target/iscsi/iscsi_target_configfs.c @@ -1608,6 +1608,7 @@ static int lio_tpg_shutdown_session(stru return 0; } atomic_set(&sess->session_reinstatement, 1); + atomic_set(&sess->session_fall_back_to_erl0, 1); spin_unlock(&sess->conn_lock); iscsit_stop_time2retain_timer(sess); --- a/drivers/target/iscsi/iscsi_target_login.c +++ b/drivers/target/iscsi/iscsi_target_login.c @@ -195,6 +195,7 @@ int iscsi_check_for_session_reinstatemen initiatorname_param->value) && (sess_p->sess_ops->SessionType == sessiontype))) { atomic_set(&sess_p->session_reinstatement, 1); + atomic_set(&sess_p->session_fall_back_to_erl0, 1); spin_unlock(&sess_p->conn_lock); iscsit_inc_session_usage_count(sess_p); iscsit_stop_time2retain_timer(sess_p);