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author | Ming Lei <ming.lei@redhat.com> | 2018-03-13 17:42:42 +0800 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2018-03-14 23:31:13 -0400 |
commit | b5b6e8c8d3b4cbeb447a0f10c7d5de3caa573299 (patch) | |
tree | 50a246c6410e50d21c359d84b328b722860627d2 /drivers/scsi | |
parent | 2f31115e940c4afd49b99c33123534e2ac924ffb (diff) | |
download | linux-b5b6e8c8d3b4cbeb447a0f10c7d5de3caa573299.tar.gz linux-b5b6e8c8d3b4cbeb447a0f10c7d5de3caa573299.tar.bz2 linux-b5b6e8c8d3b4cbeb447a0f10c7d5de3caa573299.zip |
scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity
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 <osandov@fb.com>,
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Cc: James Bottomley <james.bottomley@hansenpartnership.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: Don Brace <don.brace@microsemi.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Fixes: 84676c1f21e8 ("genirq/affinity: assign vectors to all possible CPUs")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r-- | drivers/scsi/virtio_scsi.c | 59 |
1 files changed, 3 insertions, 56 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 7c28e8d4955a..54e3a0f6844c 100644 --- 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 virtio_scsi *vscsi, void *buf) 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 virtio_scsi *vscsi, void *buf) } 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_Host *sh, 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_pick_vq_mq(struct virtio_scsi *vscsi, 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 scsi_target *starget) 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 virtscsi_host_template_single = { .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 virtscsi_host_template_multi = { .target_destroy = virtscsi_target_destroy, .map_queues = virtscsi_map_queues, .track_queue_depth = 1, + .force_blk_mq = 1, }; #define virtscsi_config_get(vdev, fld) \ |