From patchwork Fri May 12 13:15:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 9724117 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 706E3600CB for ; Fri, 12 May 2017 13:15:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 54AC52881E for ; Fri, 12 May 2017 13:15:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4913628820; Fri, 12 May 2017 13:15:51 +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 F2E5028823 for ; Fri, 12 May 2017 13:15:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756377AbdELNPs (ORCPT ); Fri, 12 May 2017 09:15:48 -0400 Received: from prv3-mh.provo.novell.com ([137.65.250.26]:36267 "EHLO prv3-mh.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755393AbdELNPq (ORCPT ); Fri, 12 May 2017 09:15:46 -0400 Received: from apollon.suse.de.de (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by prv3-mh.provo.novell.com with ESMTP (TLS encrypted); Fri, 12 May 2017 07:15:33 -0600 From: Martin Wilck To: "Martin K. Petersen" , Hannes Reinecke Cc: Bart Van Assche , Mauricio Faria de Oliveira , linux-scsi@vger.kernel.org Subject: [PATCH v2 3/4] scsi_dh_alua: do not call BUG_ON when updating port group Date: Fri, 12 May 2017 15:15:07 +0200 Message-Id: <20170512131508.3231-4-mwilck@suse.com> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170512131508.3231-1-mwilck@suse.com> References: <20170512131508.3231-1-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 | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 2b60f493f90e..a59783020c66 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -652,9 +652,15 @@ 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 + */ + struct scsi_device *sdev = + h->sdev; + if (sdev) + sdev->access_state = + desc[0]; } rcu_read_unlock(); } @@ -694,11 +700,13 @@ 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); - h->sdev->access_state = + struct scsi_device *sdev = h->sdev; + if (!sdev) + continue; + sdev->access_state = (pg->state & SCSI_ACCESS_STATE_MASK); if (pg->pref) - h->sdev->access_state |= + sdev->access_state |= SCSI_ACCESS_STATE_PREFERRED; } rcu_read_unlock();