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 at redhat.com>
---
Changes from v1: add TODO, fix more warnings.
drivers/vhost/net.c | 9 +++++----
drivers/vhost/vhost.h | 6 +++---
2 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 9b3ca10..f616cef 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 2af44b7..b3363ae 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);
}
--
1.7.3.2.91.g446ac
