| Message ID | 20190807065449.23373-8-jasowang@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fixes for metadata accelreation | expand |
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c12cdadb0855..cfc11f9ed9c9 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -333,7 +333,9 @@ static void vhost_uninit_vq_maps(struct vhost_virtqueue *vq) } spin_unlock(&vq->mmu_lock); - synchronize_rcu(); + /* No need for synchronize_rcu() or kfree_rcu() since we are + * serialized with memory accessors (e.g vq mutex held). + */ for (i = 0; i < VHOST_NUM_ADDRS; i++) if (map[i])
There's no need for RCU synchronization in vhost_uninit_vq_maps() since we've already serialized with readers (memory accessors). This also avoid the possible userspace DOS through ioctl() because of the possible high latency caused by synchronize_rcu(). Reported-by: Michael S. Tsirkin <mst@redhat.com> Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address") Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/vhost.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)