From patchwork Mon Aug 7 03:21:01 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Nicholas A. Bellinger" X-Patchwork-Id: 9884343 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9F821603F9 for ; Mon, 7 Aug 2017 03:15:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9781828477 for ; Mon, 7 Aug 2017 03:15:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8C1EA2850E; Mon, 7 Aug 2017 03:15:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0614B28533 for ; Mon, 7 Aug 2017 03:15:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751493AbdHGDPG (ORCPT ); Sun, 6 Aug 2017 23:15:06 -0400 Received: from mail.linux-iscsi.org ([67.23.28.174]:42785 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751407AbdHGDPE (ORCPT ); Sun, 6 Aug 2017 23:15:04 -0400 Received: from linux-iscsi.org (localhost [127.0.0.1]) by linux-iscsi.org (Postfix) with ESMTP id 604C640B25; Mon, 7 Aug 2017 03:21:07 +0000 (UTC) From: "Nicholas A. Bellinger" To: target-devel Cc: stable , Greg-KH , Nicholas Bellinger , Mike Christie , Hannes Reinecke , Sagi Grimberg Subject: [PATCH-v4.4.y 5/6] iscsi-target: Fix delayed logout processing greater than SECONDS_FOR_LOGOUT_COMP Date: Mon, 7 Aug 2017 03:21:01 +0000 Message-Id: <1502076062-19911-6-git-send-email-nab@linux-iscsi.org> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1502076062-19911-1-git-send-email-nab@linux-iscsi.org> References: <1502076062-19911-1-git-send-email-nab@linux-iscsi.org> Sender: target-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Nicholas Bellinger commit 105fa2f44e504c830697b0c794822112d79808dc upstream. This patch fixes a BUG() in iscsit_close_session() that could be triggered when iscsit_logout_post_handler() execution from within tx thread context was not run for more than SECONDS_FOR_LOGOUT_COMP (15 seconds), and the TCP connection didn't already close before then forcing tx thread context to automatically exit. This would manifest itself during explicit logout as: [33206.974254] 1 connection(s) still exist for iSCSI session to iqn.1993-08.org.debian:01:3f5523242179 [33206.980184] INFO: NMI handler (kgdb_nmi_handler) took too long to run: 2100.772 msecs [33209.078643] ------------[ cut here ]------------ [33209.078646] kernel BUG at drivers/target/iscsi/iscsi_target.c:4346! Normally when explicit logout attempt fails, the tx thread context exits and iscsit_close_connection() from rx thread context does the extra cleanup once it detects conn->conn_logout_remove has not been cleared by the logout type specific post handlers. To address this special case, if the logout post handler in tx thread context detects conn->tx_thread_active has already been cleared, simply return and exit in order for existing iscsit_close_connection() logic from rx thread context do failed logout cleanup. Reported-by: Bart Van Assche Tested-by: Bart Van Assche Cc: Mike Christie Cc: Hannes Reinecke Cc: Sagi Grimberg Tested-by: Gary Guo Tested-by: Chu Yuan Lin Signed-off-by: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 7b42d12..31d5d9c 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -4591,8 +4591,11 @@ static void iscsit_logout_post_handler_closesession( * always sleep waiting for RX/TX thread shutdown to complete * within iscsit_close_connection(). */ - if (conn->conn_transport->transport_type == ISCSI_TCP) + if (conn->conn_transport->transport_type == ISCSI_TCP) { sleep = cmpxchg(&conn->tx_thread_active, true, false); + if (!sleep) + return; + } atomic_set(&conn->conn_logout_remove, 0); complete(&conn->conn_logout_comp); @@ -4608,8 +4611,11 @@ static void iscsit_logout_post_handler_samecid( { int sleep = 1; - if (conn->conn_transport->transport_type == ISCSI_TCP) + if (conn->conn_transport->transport_type == ISCSI_TCP) { sleep = cmpxchg(&conn->tx_thread_active, true, false); + if (!sleep) + return; + } atomic_set(&conn->conn_logout_remove, 0); complete(&conn->conn_logout_comp);