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authorMike Christie <michael.christie@oracle.com>2023-03-21 05:06:22 +0300
committerMichael S. Tsirkin <mst@redhat.com>2023-04-21 10:02:30 +0300
commitced9eb376ab716ec5b06bef8c3e05608b8eb6700 (patch)
tree195dc0c8936a0ff8e62f418dae25e7d1d35c4267 /drivers/vhost
parenteb1b291466376ad4d2f0a42392a2cd9f0e4983e5 (diff)
downloadlinux-ced9eb376ab716ec5b06bef8c3e05608b8eb6700.tar.xz
vhost-scsi: Check for a cleared backend before queueing an event
We currenly hold the vhost_scsi_mutex while clearing the endpoint and while performing vhost_scsi_do_plug, so tpg->vhost_scsi can't be freed from uder us, and to make sure anything queued is handled by the full call in vhost_scsi_clear_endpoint. This patch removes the need for the vhost_scsi_mutex for the latter case. In the next patches, we won't hold the vhost_scsi_mutex while flushing so this patch adds a check for the clearing of the virtqueue from vhost_scsi_clear_endpoint. We then know that once vhost_scsi_clear_endpoint has cleared the backend that no new events will be queued, and the flush after the vhost_vq_set_backend(vq, NULL) call will see everything that's been queued to that point. So the flush will then handle all events without the need for the vhost_scsi_mutex. Signed-off-by: Mike Christie <michael.christie@oracle.com> Message-Id: <20230321020624.13323-6-michael.christie@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/scsi.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index c945136ecf18..ba8097fcea43 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -2010,9 +2010,17 @@ vhost_scsi_do_plug(struct vhost_scsi_tpg *tpg,
vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
mutex_lock(&vq->mutex);
+ /*
+ * We can't queue events if the backend has been cleared, because
+ * we could end up queueing an event after the flush.
+ */
+ if (!vhost_vq_get_backend(vq))
+ goto unlock;
+
if (vhost_has_feature(vq, VIRTIO_SCSI_F_HOTPLUG))
vhost_scsi_send_evt(vs, tpg, lun,
VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
+unlock:
mutex_unlock(&vq->mutex);
}