From patchwork Fri Jan 17 23:33:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gabriel Krisman Bertazi X-Patchwork-Id: 11339997 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7C93A138D for ; Fri, 17 Jan 2020 23:33:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A92A21835 for ; Fri, 17 Jan 2020 23:33:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730135AbgAQXdf (ORCPT ); Fri, 17 Jan 2020 18:33:35 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44820 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729798AbgAQXdf (ORCPT ); Fri, 17 Jan 2020 18:33:35 -0500 Received: from localhost (unknown [IPv6:2610:98:8005::787]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: krisman) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id D8BC0293EDA; Fri, 17 Jan 2020 23:33:32 +0000 (GMT) From: Gabriel Krisman Bertazi To: lduncan@suse.com Cc: cleech@redhat.com, jejb@linux.ibm.com, martin.petersen@oracle.com, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, Frank Mayhar , kernel@collabora.com, Khazhismel Kumykov , Gabriel Krisman Bertazi Subject: [PATCH] iscsi: Add support for asynchronous iSCSI session destruction Date: Fri, 17 Jan 2020 18:33:28 -0500 Message-Id: <20200117233328.1052604-1-krisman@collabora.com> X-Mailer: git-send-email 2.25.0.rc2 MIME-Version: 1.0 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org From: Frank Mayhar iSCSI session destruction can be arbitrarily slow, since it might require network operations and serialization inside the scsi layer. This patch adds a new user event to trigger the destruction work asynchronously, releasing the rx_queue_mutex as soon as the operation is queued and before it is performed. This change allow other operations to run in other sessions in the meantime, removing one of the major iSCSI bottlenecks for us. To prevent the session from being used after the destruction request, we remove it immediately from the sesslist. This simplifies the locking required during the asynchronous removal. Co-developed-by: Khazhismel Kumykov Signed-off-by: Khazhismel Kumykov Signed-off-by: Frank Mayhar Co-developed-by: Gabriel Krisman Bertazi Signed-off-by: Gabriel Krisman Bertazi --- This patch requires a patch that just went upstream to apply cleanly. it is ("iscsi: Don't destroy session if there are outstanding connections"), which was just merged by Martin into 5.6/scsi-queue. Please make sure you have it in your tree, otherwise this one won't apply. drivers/scsi/scsi_transport_iscsi.c | 36 +++++++++++++++++++++++++++++ include/scsi/iscsi_if.h | 1 + include/scsi/scsi_transport_iscsi.h | 1 + 3 files changed, 38 insertions(+) diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c index ba6cfaf71aef..e9a8e0317b0d 100644 --- a/drivers/scsi/scsi_transport_iscsi.c +++ b/drivers/scsi/scsi_transport_iscsi.c @@ -95,6 +95,8 @@ static DECLARE_WORK(stop_conn_work, stop_conn_work_fn); static atomic_t iscsi_session_nr; /* sysfs session id for next new session */ static struct workqueue_struct *iscsi_eh_timer_workq; +static struct workqueue_struct *iscsi_destroy_workq; + static DEFINE_IDA(iscsi_sess_ida); /* * list of registered transports and lock that must @@ -1615,6 +1617,7 @@ static struct sock *nls; static DEFINE_MUTEX(rx_queue_mutex); static LIST_HEAD(sesslist); +static LIST_HEAD(sessdestroylist); static DEFINE_SPINLOCK(sesslock); static LIST_HEAD(connlist); static LIST_HEAD(connlist_err); @@ -2035,6 +2038,14 @@ static void __iscsi_unbind_session(struct work_struct *work) ISCSI_DBG_TRANS_SESSION(session, "Completed target removal\n"); } +static void __iscsi_destroy_session(struct work_struct *work) +{ + struct iscsi_cls_session *session = + container_of(work, struct iscsi_cls_session, destroy_work); + + session->transport->destroy_session(session); +} + struct iscsi_cls_session * iscsi_alloc_session(struct Scsi_Host *shost, struct iscsi_transport *transport, int dd_size) @@ -2057,6 +2068,7 @@ iscsi_alloc_session(struct Scsi_Host *shost, struct iscsi_transport *transport, INIT_WORK(&session->block_work, __iscsi_block_session); INIT_WORK(&session->unbind_work, __iscsi_unbind_session); INIT_WORK(&session->scan_work, iscsi_scan_session); + INIT_WORK(&session->destroy_work, __iscsi_destroy_session); spin_lock_init(&session->lock); /* this is released in the dev's release function */ @@ -3617,6 +3629,23 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group) else transport->destroy_session(session); break; + case ISCSI_UEVENT_DESTROY_SESSION_ASYNC: + session = iscsi_session_lookup(ev->u.d_session.sid); + if (!session) + err = -EINVAL; + else if (iscsi_session_has_conns(ev->u.d_session.sid)) + err = -EBUSY; + else { + unsigned long flags; + + /* Prevent this session from being found again */ + spin_lock_irqsave(&sesslock, flags); + list_move(&session->sess_list, &sessdestroylist); + spin_unlock_irqrestore(&sesslock, flags); + + queue_work(iscsi_destroy_workq, &session->destroy_work); + } + break; case ISCSI_UEVENT_UNBIND_SESSION: session = iscsi_session_lookup(ev->u.d_session.sid); if (session) @@ -4662,8 +4691,14 @@ static __init int iscsi_transport_init(void) goto release_nls; } + iscsi_destroy_workq = create_singlethread_workqueue("iscsi_destroy"); + if (!iscsi_destroy_workq) + goto destroy_wq; + return 0; +destroy_wq: + destroy_workqueue(iscsi_eh_timer_workq); release_nls: netlink_kernel_release(nls); unregister_flashnode_bus: @@ -4685,6 +4720,7 @@ static __init int iscsi_transport_init(void) static void __exit iscsi_transport_exit(void) { + destroy_workqueue(iscsi_destroy_workq); destroy_workqueue(iscsi_eh_timer_workq); netlink_kernel_release(nls); bus_unregister(&iscsi_flashnode_bus); diff --git a/include/scsi/iscsi_if.h b/include/scsi/iscsi_if.h index 92b11c7e0b4f..deacaee53e61 100644 --- a/include/scsi/iscsi_if.h +++ b/include/scsi/iscsi_if.h @@ -60,6 +60,7 @@ enum iscsi_uevent_e { ISCSI_UEVENT_LOGOUT_FLASHNODE_SID = UEVENT_BASE + 30, ISCSI_UEVENT_SET_CHAP = UEVENT_BASE + 31, ISCSI_UEVENT_GET_HOST_STATS = UEVENT_BASE + 32, + ISCSI_UEVENT_DESTROY_SESSION_ASYNC = UEVENT_BASE + 33, /* up events */ ISCSI_KEVENT_RECV_PDU = KEVENT_BASE + 1, diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h index 2129dc9e2dec..fa8814245796 100644 --- a/include/scsi/scsi_transport_iscsi.h +++ b/include/scsi/scsi_transport_iscsi.h @@ -226,6 +226,7 @@ struct iscsi_cls_session { struct work_struct unblock_work; struct work_struct scan_work; struct work_struct unbind_work; + struct work_struct destroy_work; /* recovery fields */ int recovery_tmo;