From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755426AbcBCXGu (ORCPT ); Wed, 3 Feb 2016 18:06:50 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:47146 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757643AbcBCWhk (ORCPT ); Wed, 3 Feb 2016 17:37:40 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Christoph Hellwig , Hannes Reinecke , Andy Grover , Mike Christie , Nicholas Bellinger , Luis Henriques Subject: [PATCH 3.16.y-ckt 135/180] iscsi-target: Fix potential dead-lock during node acl delete Date: Wed, 3 Feb 2016 22:32:21 +0000 Message-Id: <1454538786-12215-136-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1454538786-12215-1-git-send-email-luis.henriques@canonical.com> References: <1454538786-12215-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt24 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Nicholas Bellinger commit 26a99c19f810b2593410899a5b304b21b47428a6 upstream. This patch is a iscsi-target specific bug-fix for a dead-lock that can occur during explicit struct se_node_acl->acl_group se_session deletion via configfs rmdir(2), when iscsi-target time2retain timer is still active. It changes iscsi-target to obtain se_portal_group->session_lock internally using spin_in_locked() to check for the specific se_node_acl configfs shutdown rmdir(2) case. Note this patch is intended for stable, and the subsequent v4.5-rc patch converts target_core_tpg.c to use proper se_sess->sess_kref reference counting for both se_node_acl deletion + se_node_acl->queue_depth se_session restart. Reported-by:: Sagi Grimberg Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Andy Grover Cc: Mike Christie Signed-off-by: Nicholas Bellinger Signed-off-by: Luis Henriques --- drivers/target/iscsi/iscsi_target_configfs.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c index ae03f3e5de1e..e7785e29a858 100644 --- a/drivers/target/iscsi/iscsi_target_configfs.c +++ b/drivers/target/iscsi/iscsi_target_configfs.c @@ -1889,7 +1889,8 @@ static void lio_tpg_release_fabric_acl( } /* - * Called with spin_lock_bh(struct se_portal_group->session_lock) held.. + * Called with spin_lock_irq(struct se_portal_group->session_lock) held + * or not held. * * Also, this function calls iscsit_inc_session_usage_count() on the * struct iscsi_session in question. @@ -1897,19 +1898,32 @@ static void lio_tpg_release_fabric_acl( static int lio_tpg_shutdown_session(struct se_session *se_sess) { struct iscsi_session *sess = se_sess->fabric_sess_ptr; + struct se_portal_group *se_tpg = se_sess->se_tpg; + bool local_lock = false; + + if (!spin_is_locked(&se_tpg->session_lock)) { + spin_lock_irq(&se_tpg->session_lock); + local_lock = true; + } spin_lock(&sess->conn_lock); if (atomic_read(&sess->session_fall_back_to_erl0) || atomic_read(&sess->session_logout) || (sess->time2retain_timer_flags & ISCSI_TF_EXPIRED)) { spin_unlock(&sess->conn_lock); + if (local_lock) + spin_unlock_irq(&sess->conn_lock); return 0; } atomic_set(&sess->session_reinstatement, 1); spin_unlock(&sess->conn_lock); iscsit_stop_time2retain_timer(sess); + spin_unlock_irq(&se_tpg->session_lock); + iscsit_stop_session(sess, 1, 1); + if (!local_lock) + spin_lock_irq(&se_tpg->session_lock); return 1; }