@@ -1691,11 +1691,10 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
if (!tpg)
continue;
- mutex_lock(&tpg->tv_tpg_mutex);
tv_tport = tpg->tport;
if (!tv_tport) {
ret = -ENODEV;
- goto err_tpg;
+ goto err_dev;
}
if (strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
@@ -1704,35 +1703,51 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
tv_tport->tport_name, tpg->tport_tpgt,
t->vhost_wwpn, t->vhost_tpgt);
ret = -EINVAL;
- goto err_tpg;
+ goto err_dev;
}
+ match = true;
+ }
+ if (!match)
+ goto free_vs_tpg;
+
+ /* Prevent new cmds from starting and accessing the tpgs/sessions */
+ for (i = 0; i < vs->dev.nvqs; i++) {
+ vq = &vs->vqs[i].vq;
+ mutex_lock(&vq->mutex);
+ vhost_vq_set_backend(vq, NULL);
+ mutex_unlock(&vq->mutex);
+ }
+ /* Make sure cmds are not running before tearing them down. */
+ vhost_scsi_flush(vs);
+
+ for (i = 0; i < vs->dev.nvqs; i++) {
+ vq = &vs->vqs[i].vq;
+ vhost_scsi_destroy_vq_cmds(vq);
+ }
+
+ /*
+ * We can now release our hold on the tpg and sessions and userspace
+ * can free them after this point.
+ */
+ for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
+ target = i;
+ tpg = vs->vs_tpg[target];
+ if (!tpg)
+ continue;
+
+ mutex_lock(&tpg->tv_tpg_mutex);
+
tpg->tv_tpg_vhost_count--;
tpg->vhost_scsi = NULL;
vs->vs_tpg[target] = NULL;
- match = true;
+
mutex_unlock(&tpg->tv_tpg_mutex);
- /*
- * Release se_tpg->tpg_group.cg_item configfs dependency now
- * to allow vhost-scsi WWPN se_tpg->tpg_group shutdown to occur.
- */
+
se_tpg = &tpg->se_tpg;
target_undepend_item(&se_tpg->tpg_group.cg_item);
}
- if (match) {
- for (i = 0; i < vs->dev.nvqs; i++) {
- vq = &vs->vqs[i].vq;
- mutex_lock(&vq->mutex);
- vhost_vq_set_backend(vq, NULL);
- mutex_unlock(&vq->mutex);
- }
- /* Make sure cmds are not running before tearing them down. */
- vhost_scsi_flush(vs);
- for (i = 0; i < vs->dev.nvqs; i++) {
- vq = &vs->vqs[i].vq;
- vhost_scsi_destroy_vq_cmds(vq);
- }
- }
+free_vs_tpg:
/*
* Act as synchronize_rcu to make sure access to
* old vs->vs_tpg is finished.
@@ -1745,8 +1760,6 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
mutex_unlock(&vhost_scsi_mutex);
return 0;
-err_tpg:
- mutex_unlock(&tpg->tv_tpg_mutex);
err_dev:
mutex_unlock(&vs->dev.mutex);
mutex_unlock(&vhost_scsi_mutex);
We currently hold the vhost_scsi_mutex the entire time we are running vhost_scsi_clear_endpoint. One of the reasons for this is that it prevents userspace from being able to free the se_tpg from under us after we have called target_undepend_item. However, it forces management operations for for other devices to have to wait on a flakey device's: vhost_scsi_clear_endpoint -> vhost_scsi_flush() call which can which can take a long time. This moves the target_undepend_item call and the tpg unsetup code to after we have stopped new IO from starting up and after we have waited on running IO. We can then release our refcount on the tpg and session knowing our device is no longer accessing them. We can then drop the vhost_scsi_mutex use during thee flush call in later patches in this set, when we have removed other reasons for holding it. Signed-off-by: Mike Christie <michael.christie@oracle.com> --- drivers/vhost/scsi.c | 61 +++++++++++++++++++++++++++----------------- 1 file changed, 37 insertions(+), 24 deletions(-)