Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull vhost fixes from Michael Tsirkin:
 "vhost: more fixes for 3.11

  This includes some fixes for vhost net and scsi drivers.

  The test module has already been reworked to avoid rcu usage, but the
  necessary core changes are missing, we fixed this.

  Unlikely to affect any real-world users, but it's early in the cycle
  so, let's merge them"

(It was earlier when Michael originally sent the email, but it somehot
got missed in the flood, so here it is after -rc2)

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost: Remove custom vhost rcu usage
  vhost-scsi: Always access vq->private_data under vq mutex
  vhost-net: Always access vq->private_data under vq mutex

1 files changed, 6 insertions, 11 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 06adf31a9248..0c27c7df1b09 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -902,19 +902,15 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
         int head, ret;
         u8 target;
 
+        mutex_lock(&vq->mutex);
         /*
          * We can handle the vq only after the endpoint is setup by calling the
          * VHOST_SCSI_SET_ENDPOINT ioctl.
-         *
-         * TODO: Check that we are running from vhost_worker which acts
-         * as read-side critical section for vhost kind of RCU.
-         * See the comments in struct vhost_virtqueue in drivers/vhost/vhost.h
          */
-        vs_tpg = rcu_dereference_check(vq->private_data, 1);
+        vs_tpg = vq->private_data;
         if (!vs_tpg)
-                return;
+                goto out;
 
-        mutex_lock(&vq->mutex);
         vhost_disable_notify(&vs->dev, vq);
 
         for (;;) {
@@ -1064,6 +1060,7 @@ err_free:
         vhost_scsi_free_cmd(cmd);
 err_cmd:
         vhost_scsi_send_bad_target(vs, vq, head, out);
+out:
         mutex_unlock(&vq->mutex);
 }
 
@@ -1232,9 +1229,8 @@ vhost_scsi_set_endpoint(struct vhost_scsi *vs,
                        sizeof(vs->vs_vhost_wwpn));
                 for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
                         vq = &vs->vqs[i].vq;
-                        /* Flushing the vhost_work acts as synchronize_rcu */
                         mutex_lock(&vq->mutex);
-                        rcu_assign_pointer(vq->private_data, vs_tpg);
+                        vq->private_data = vs_tpg;
                         vhost_init_used(vq);
                         mutex_unlock(&vq->mutex);
                 }
@@ -1313,9 +1309,8 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
         if (match) {
                 for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
                         vq = &vs->vqs[i].vq;
-                        /* Flushing the vhost_work acts as synchronize_rcu */
                         mutex_lock(&vq->mutex);
-                        rcu_assign_pointer(vq->private_data, NULL);
+                        vq->private_data = NULL;
                         mutex_unlock(&vq->mutex);
                 }
         }