From patchwork Thu Sep 17 18:16:49 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Leech X-Patchwork-Id: 7209671 Return-Path: X-Original-To: patchwork-linux-scsi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 1D0A59F380 for ; Thu, 17 Sep 2015 18:17:12 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2732520780 for ; Thu, 17 Sep 2015 18:17:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6FA32066D for ; Thu, 17 Sep 2015 18:17:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752785AbbIQSRC (ORCPT ); Thu, 17 Sep 2015 14:17:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42298 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751371AbbIQSRA (ORCPT ); Thu, 17 Sep 2015 14:17:00 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 934998E68D; Thu, 17 Sep 2015 18:17:00 +0000 (UTC) Received: from straylight.hirudinean.org.com (ovpn-113-78.phx2.redhat.com [10.3.113.78]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t8HIH07x025196; Thu, 17 Sep 2015 14:17:00 -0400 From: Chris Leech To: , Subject: [PATCH] iscsi: make mutex for target scanning and unbinding per-session Date: Thu, 17 Sep 2015 11:16:49 -0700 Message-Id: <1442513809-11467-1-git-send-email-cleech@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently the iSCSI transport class synchronises target scanning and unbinding with a host level mutex. For multi-session hosts (offloading iSCSI HBAs) connecting to storage arrays that may implement one target-per-lun, this can result in the target scan work for hundreds of sessions being serialized behind a single mutex. With slow enough response times, this can cause scan requests initiated from userspace to block on the mutex long enough to trigger 120 sec hung task warnings. I can't see any reason not to move this to a session level mutex and let the target scans run in parallel, speeding up connecting to a large number of targets. Note that as iscsi_tcp creates a virtual host for each session, software iSCSI is effectively doing this already. Signed-off-by: Chris Leech Reviewed-by: Mike Christie --- drivers/scsi/scsi_transport_iscsi.c | 19 ++++++------------- include/scsi/scsi_transport_iscsi.h | 2 +- 2 files changed, 7 insertions(+), 14 deletions(-) diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c index e4b3d8f..9daeb7f 100644 --- a/drivers/scsi/scsi_transport_iscsi.c +++ b/drivers/scsi/scsi_transport_iscsi.c @@ -1569,7 +1569,6 @@ static int iscsi_setup_host(struct transport_container *tc, struct device *dev, memset(ihost, 0, sizeof(*ihost)); atomic_set(&ihost->nr_scans, 0); - mutex_init(&ihost->mutex); iscsi_bsg_host_add(shost, ihost); /* ignore any bsg add error - we just can't do sgio */ @@ -1789,8 +1788,6 @@ static int iscsi_user_scan_session(struct device *dev, void *data) { struct iscsi_scan_data *scan_data = data; struct iscsi_cls_session *session; - struct Scsi_Host *shost; - struct iscsi_cls_host *ihost; unsigned long flags; unsigned int id; @@ -1801,10 +1798,7 @@ static int iscsi_user_scan_session(struct device *dev, void *data) ISCSI_DBG_TRANS_SESSION(session, "Scanning session\n"); - shost = iscsi_session_to_shost(session); - ihost = shost->shost_data; - - mutex_lock(&ihost->mutex); + mutex_lock(&session->mutex); spin_lock_irqsave(&session->lock, flags); if (session->state != ISCSI_SESSION_LOGGED_IN) { spin_unlock_irqrestore(&session->lock, flags); @@ -1823,7 +1817,7 @@ static int iscsi_user_scan_session(struct device *dev, void *data) } user_scan_exit: - mutex_unlock(&ihost->mutex); + mutex_unlock(&session->mutex); ISCSI_DBG_TRANS_SESSION(session, "Completed session scan\n"); return 0; } @@ -1999,26 +1993,24 @@ static void __iscsi_unbind_session(struct work_struct *work) struct iscsi_cls_session *session = container_of(work, struct iscsi_cls_session, unbind_work); - struct Scsi_Host *shost = iscsi_session_to_shost(session); - struct iscsi_cls_host *ihost = shost->shost_data; unsigned long flags; unsigned int target_id; ISCSI_DBG_TRANS_SESSION(session, "Unbinding session\n"); /* Prevent new scans and make sure scanning is not in progress */ - mutex_lock(&ihost->mutex); + mutex_lock(&session->mutex); spin_lock_irqsave(&session->lock, flags); if (session->target_id == ISCSI_MAX_TARGET) { spin_unlock_irqrestore(&session->lock, flags); - mutex_unlock(&ihost->mutex); + mutex_unlock(&session->mutex); return; } target_id = session->target_id; session->target_id = ISCSI_MAX_TARGET; spin_unlock_irqrestore(&session->lock, flags); - mutex_unlock(&ihost->mutex); + mutex_unlock(&session->mutex); if (session->ida_used) ida_simple_remove(&iscsi_sess_ida, target_id); @@ -2051,6 +2043,7 @@ iscsi_alloc_session(struct Scsi_Host *shost, struct iscsi_transport *transport, INIT_WORK(&session->unbind_work, __iscsi_unbind_session); INIT_WORK(&session->scan_work, iscsi_scan_session); spin_lock_init(&session->lock); + mutex_init(&session->mutex); /* this is released in the dev's release function */ scsi_host_get(shost); diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h index 6183d20..acf9d9d 100644 --- a/include/scsi/scsi_transport_iscsi.h +++ b/include/scsi/scsi_transport_iscsi.h @@ -238,6 +238,7 @@ struct iscsi_cls_session { struct work_struct unblock_work; struct work_struct scan_work; struct work_struct unbind_work; + struct mutex mutex; /* recovery fields */ int recovery_tmo; @@ -272,7 +273,6 @@ struct iscsi_cls_session { struct iscsi_cls_host { atomic_t nr_scans; - struct mutex mutex; struct request_queue *bsg_q; uint32_t port_speed; uint32_t port_state;