From patchwork Fri Apr 28 13:06:26 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 9704641 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 1F4A660225 for ; Fri, 28 Apr 2017 13:07:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 11D8228678 for ; Fri, 28 Apr 2017 13:07:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 06D2A28687; Fri, 28 Apr 2017 13:07:03 +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 B647828678 for ; Fri, 28 Apr 2017 13:07:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1164247AbdD1NHB (ORCPT ); Fri, 28 Apr 2017 09:07:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:46152 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932337AbdD1NG6 (ORCPT ); Fri, 28 Apr 2017 09:06:58 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1EA69AD25; Fri, 28 Apr 2017 13:06:57 +0000 (UTC) From: Martin Wilck To: "Martin K. Petersen" , Hannes Reinecke Cc: Bart Van Assche , Mauricio Faria de Oliveira , linux-scsi@vger.kernel.org Subject: [PATCH 3/3] scsi_dh_alua: do not call BUG_ON when updating port group Date: Fri, 28 Apr 2017 15:06:26 +0200 Message-Id: <20170428130626.32162-4-mwilck@suse.com> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170428130626.32162-1-mwilck@suse.com> References: <20170428130626.32162-1-mwilck@suse.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP alua_rtpg() can race with alua_bus_detach(). The assertion that alua_dh_data *h->sdev must be non-NULL is not guaranteed because alua_bus_detach sets this field to NULL before removing the entry from the port group's dh_list. This happens when a device is about to be removed, so don't BUG out but continue silently. Signed-off-by: Martin Wilck Reviewed-by: Hannes Reinecke --- drivers/scsi/device_handler/scsi_dh_alua.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 501855bde633..274fb49d0801 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -652,9 +652,13 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) rcu_read_lock(); list_for_each_entry_rcu(h, &tmp_pg->dh_list, node) { - /* h->sdev should always be valid */ - BUG_ON(!h->sdev); - h->sdev->access_state = desc[0]; + /* + * We might be racing with + * alua_bus_detach here + */ + if (h->sdev) + h->sdev->access_state = + desc[0]; } rcu_read_unlock(); } @@ -694,7 +698,8 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) pg->expiry = 0; rcu_read_lock(); list_for_each_entry_rcu(h, &pg->dh_list, node) { - BUG_ON(!h->sdev); + if (!h->sdev) + continue; h->sdev->access_state = (pg->state & SCSI_ACCESS_STATE_MASK); if (pg->pref)