diff mbox series

[v2,5/7] vhost-scsi: Check for a cleared backend before queueing an event

Message ID 20230321020624.13323-6-michael.christie@oracle.com (mailing list archive)
State New, archived
Headers show
Series vhost-scsi: Fix crashes and management op hangs | expand

Commit Message

Mike Christie March 21, 2023, 2:06 a.m. UTC
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>
 drivers/vhost/scsi.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series


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;
+	/*
+	 * 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,