vhost: rcu annotation fixup

When built with rcu checks enabled, vhost triggers
bogus warnings as vhost features are read without
dev->mutex sometimes, and private pointer is read
with our kind of rcu where work serves as a
read side critical section.

Fixing it properly is not trivial.
Disable the warnings by stubbing out the checks for now.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 8 insertions, 7 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 9b3ca103135f..f616cefc95ba 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -128,8 +128,7 @@ static void handle_tx(struct vhost_net *net)
         size_t hdr_size;
         struct socket *sock;
 
-        /* TODO: check that we are running from vhost_worker?
-         * Not sure it's worth it, it's straight-forward enough. */
+        /* TODO: check that we are running from vhost_worker? */
         sock = rcu_dereference_check(vq->private_data, 1);
         if (!sock)
                 return;
@@ -306,7 +305,8 @@ static void handle_rx_big(struct vhost_net *net)
         size_t len, total_len = 0;
         int err;
         size_t hdr_size;
-        struct socket *sock = rcu_dereference(vq->private_data);
+        /* TODO: check that we are running from vhost_worker? */
+        struct socket *sock = rcu_dereference_check(vq->private_data, 1);
         if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
                 return;
 
@@ -415,7 +415,8 @@ static void handle_rx_mergeable(struct vhost_net *net)
         int err, headcount;
         size_t vhost_hlen, sock_hlen;
         size_t vhost_len, sock_len;
-        struct socket *sock = rcu_dereference(vq->private_data);
+        /* TODO: check that we are running from vhost_worker? */
+        struct socket *sock = rcu_dereference_check(vq->private_data, 1);
         if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
                 return;
 
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 2af44b7b1f3f..b3363ae38518 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -173,9 +173,9 @@ static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 {
         unsigned acked_features;
 
-        acked_features =
-                rcu_dereference_index_check(dev->acked_features,
-                                            lockdep_is_held(&dev->mutex));
+        /* TODO: check that we are running from vhost_worker or dev mutex is
+         * held? */
+        acked_features = rcu_dereference_index_check(dev->acked_features, 1);
         return acked_features & (1 << bit);
 }