From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B66BC43381 for ; Wed, 6 Mar 2019 18:23:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D70C205F4 for ; Wed, 6 Mar 2019 18:23:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726384AbfCFSXx (ORCPT ); Wed, 6 Mar 2019 13:23:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38672 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725747AbfCFSXx (ORCPT ); Wed, 6 Mar 2019 13:23:53 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E4BA680B55; Wed, 6 Mar 2019 18:23:52 +0000 (UTC) Received: from straylight.hirudinean.org (ovpn-123-76.rdu2.redhat.com [10.10.123.76]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D9FD860E3D; Wed, 6 Mar 2019 18:23:51 +0000 (UTC) Date: Wed, 6 Mar 2019 10:23:49 -0800 From: Chris Leech To: Lee Duncan Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, hare@suse.de, Lee Duncan Subject: Re: [PATCH v2] scsi:libiscsi: Hold back_lock when calling iscsi_complete_task Message-ID: <20190306182349.GB68002@straylight.hirudinean.org> Mail-Followup-To: Chris Leech , Lee Duncan , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, hare@suse.de, Lee Duncan References: <20190225174130.29496-1-leeman.duncan@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190225174130.29496-1-leeman.duncan@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Wed, 06 Mar 2019 18:23:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 25, 2019 at 09:41:30AM -0800, Lee Duncan wrote: > From: Lee Duncan > > If there is an error queueing an iscsi command in > iscsi_queuecommand(), for example if the transport fails > to take the command in sessuin->tt->xmit_task(), then > the error path can call iscsi_complete_task() without > first aquiring the back_lock as required. This can > lead to things like ITT pool can get corrupt, resulting > in duplicate ITTs being sent out. > > The solution is to hold the back_lock around > iscsi_complete_task() calls, and to add a little commenting > to help others understand when back_lock must be held. > > Signed-off-by: Lee Duncan > --- Lee, Quick question, can you confirm that you tested this with lockdep? It seems right to me, it's just that we've been hit with lockdep problems dealing with these locks before. - Chris > drivers/scsi/libiscsi.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c > index b8d325ce8754..ef7871e8c6bd 100644 > --- a/drivers/scsi/libiscsi.c > +++ b/drivers/scsi/libiscsi.c > @@ -838,7 +838,7 @@ EXPORT_SYMBOL_GPL(iscsi_conn_send_pdu); > * @datalen: len of buffer > * > * iscsi_cmd_rsp sets up the scsi_cmnd fields based on the PDU and > - * then completes the command and task. > + * then completes the command and task. called under back_lock > **/ > static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr, > struct iscsi_task *task, char *data, > @@ -941,6 +941,9 @@ static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr, > * @conn: iscsi connection > * @hdr: iscsi pdu > * @task: scsi command task > + * > + * iscsi_data_in_rsp sets up the scsi_cmnd fields based on the data received > + * then completes the command and task. called under back_lock > **/ > static void > iscsi_data_in_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr, > @@ -1025,6 +1028,16 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr) > return 0; > } > > +/** > + * iscsi_nop_out_rsp - SCSI NOP Response processing > + * @task: scsi command task > + * @nop: the nop structure > + * @data: where to put the data > + * @datalen: length of data > + * > + * iscsi_nop_out_rsp handles nop response from use or > + * from user space. called under back_lock > + **/ > static int iscsi_nop_out_rsp(struct iscsi_task *task, > struct iscsi_nopin *nop, char *data, int datalen) > { > @@ -1791,7 +1804,9 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc) > return 0; > > prepd_reject: > + spin_lock_bh(&session->back_lock); > iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ); > + spin_unlock_bh(&session->back_lock); > reject: > spin_unlock_bh(&session->frwd_lock); > ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n", > @@ -1799,7 +1814,9 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc) > return SCSI_MLQUEUE_TARGET_BUSY; > > prepd_fault: > + spin_lock_bh(&session->back_lock); > iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ); > + spin_unlock_bh(&session->back_lock); > fault: > spin_unlock_bh(&session->frwd_lock); > ISCSI_DBG_SESSION(session, "iscsi: cmd 0x%x is not queued (%d)\n", > @@ -3121,8 +3138,9 @@ fail_mgmt_tasks(struct iscsi_session *session, struct iscsi_conn *conn) > state = ISCSI_TASK_ABRT_SESS_RECOV; > if (task->state == ISCSI_TASK_PENDING) > state = ISCSI_TASK_COMPLETED; > + spin_lock_bh(&session->back_lock); > iscsi_complete_task(task, state); > - > + spin_unlock_bh(&session->back_lock); > } > } > > -- > 2.16.4 >