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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 27799C46470 for ; Tue, 14 Aug 2018 17:35:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D602421727 for ; Tue, 14 Aug 2018 17:35:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D602421727 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728970AbeHNUXH (ORCPT ); Tue, 14 Aug 2018 16:23:07 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57130 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725873AbeHNUXG (ORCPT ); Tue, 14 Aug 2018 16:23:06 -0400 Received: from localhost (unknown [194.244.16.108]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E48A3DF2; Tue, 14 Aug 2018 17:34:57 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Don Brace , Kashyap Desai , Paolo Bonzini , Mike Snitzer , Laurence Oberman , Ming Lei , Hannes Reinecke , Christoph Hellwig , "Martin K. Petersen" , Omar Sandoval , James Bottomley Subject: [PATCH 4.14 005/104] scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity Date: Tue, 14 Aug 2018 19:16:19 +0200 Message-Id: <20180814171515.629502779@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180814171515.270692185@linuxfoundation.org> References: <20180814171515.270692185@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei commit b5b6e8c8d3b4cbeb447a0f10c7d5de3caa573299 upstream. Since commit 84676c1f21e8ff5 ("genirq/affinity: assign vectors to all possible CPUs") it is possible to end up in a scenario where only offline CPUs are mapped to an interrupt vector. This is only an issue for the legacy I/O path since with blk-mq/scsi-mq an I/O can't be submitted to a hardware queue if the queue isn't mapped to an online CPU. Fix this issue by forcing virtio-scsi to use blk-mq. [mkp: commit desc] Cc: Omar Sandoval , Cc: "Martin K. Petersen" , Cc: James Bottomley , Cc: Christoph Hellwig , Cc: Don Brace Cc: Kashyap Desai Cc: Paolo Bonzini Cc: Mike Snitzer Cc: Laurence Oberman Fixes: 84676c1f21e8 ("genirq/affinity: assign vectors to all possible CPUs") Signed-off-by: Ming Lei Reviewed-by: Hannes Reinecke Acked-by: Paolo Bonzini Reviewed-by: Christoph Hellwig Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/virtio_scsi.c | 59 ++------------------------------------------- 1 file changed, 3 insertions(+), 56 deletions(-) --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -91,9 +91,6 @@ struct virtio_scsi_vq { struct virtio_scsi_target_state { seqcount_t tgt_seq; - /* Count of outstanding requests. */ - atomic_t reqs; - /* Currently active virtqueue for requests sent to this target. */ struct virtio_scsi_vq *req_vq; }; @@ -152,8 +149,6 @@ static void virtscsi_complete_cmd(struct struct virtio_scsi_cmd *cmd = buf; struct scsi_cmnd *sc = cmd->sc; struct virtio_scsi_cmd_resp *resp = &cmd->resp.cmd; - struct virtio_scsi_target_state *tgt = - scsi_target(sc->device)->hostdata; dev_dbg(&sc->device->sdev_gendev, "cmd %p response %u status %#02x sense_len %u\n", @@ -210,8 +205,6 @@ static void virtscsi_complete_cmd(struct } sc->scsi_done(sc); - - atomic_dec(&tgt->reqs); } static void virtscsi_vq_done(struct virtio_scsi *vscsi, @@ -580,10 +573,7 @@ static int virtscsi_queuecommand_single( struct scsi_cmnd *sc) { struct virtio_scsi *vscsi = shost_priv(sh); - struct virtio_scsi_target_state *tgt = - scsi_target(sc->device)->hostdata; - atomic_inc(&tgt->reqs); return virtscsi_queuecommand(vscsi, &vscsi->req_vqs[0], sc); } @@ -596,55 +586,11 @@ static struct virtio_scsi_vq *virtscsi_p return &vscsi->req_vqs[hwq]; } -static struct virtio_scsi_vq *virtscsi_pick_vq(struct virtio_scsi *vscsi, - struct virtio_scsi_target_state *tgt) -{ - struct virtio_scsi_vq *vq; - unsigned long flags; - u32 queue_num; - - local_irq_save(flags); - if (atomic_inc_return(&tgt->reqs) > 1) { - unsigned long seq; - - do { - seq = read_seqcount_begin(&tgt->tgt_seq); - vq = tgt->req_vq; - } while (read_seqcount_retry(&tgt->tgt_seq, seq)); - } else { - /* no writes can be concurrent because of atomic_t */ - write_seqcount_begin(&tgt->tgt_seq); - - /* keep previous req_vq if a reader just arrived */ - if (unlikely(atomic_read(&tgt->reqs) > 1)) { - vq = tgt->req_vq; - goto unlock; - } - - queue_num = smp_processor_id(); - while (unlikely(queue_num >= vscsi->num_queues)) - queue_num -= vscsi->num_queues; - tgt->req_vq = vq = &vscsi->req_vqs[queue_num]; - unlock: - write_seqcount_end(&tgt->tgt_seq); - } - local_irq_restore(flags); - - return vq; -} - static int virtscsi_queuecommand_multi(struct Scsi_Host *sh, struct scsi_cmnd *sc) { struct virtio_scsi *vscsi = shost_priv(sh); - struct virtio_scsi_target_state *tgt = - scsi_target(sc->device)->hostdata; - struct virtio_scsi_vq *req_vq; - - if (shost_use_blk_mq(sh)) - req_vq = virtscsi_pick_vq_mq(vscsi, sc); - else - req_vq = virtscsi_pick_vq(vscsi, tgt); + struct virtio_scsi_vq *req_vq = virtscsi_pick_vq_mq(vscsi, sc); return virtscsi_queuecommand(vscsi, req_vq, sc); } @@ -775,7 +721,6 @@ static int virtscsi_target_alloc(struct return -ENOMEM; seqcount_init(&tgt->tgt_seq); - atomic_set(&tgt->reqs, 0); tgt->req_vq = &vscsi->req_vqs[0]; starget->hostdata = tgt; @@ -823,6 +768,7 @@ static struct scsi_host_template virtscs .target_alloc = virtscsi_target_alloc, .target_destroy = virtscsi_target_destroy, .track_queue_depth = 1, + .force_blk_mq = 1, }; static struct scsi_host_template virtscsi_host_template_multi = { @@ -844,6 +790,7 @@ static struct scsi_host_template virtscs .target_destroy = virtscsi_target_destroy, .map_queues = virtscsi_map_queues, .track_queue_depth = 1, + .force_blk_mq = 1, }; #define virtscsi_config_get(vdev, fld) \