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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>
This commit is contained in:
Michael S. Tsirkin 2011-01-18 13:04:43 +02:00
parent fca540ab5f
commit 5e18247b02
2 changed files with 8 additions and 7 deletions
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9
drivers/vhost/net.c
View File

@ -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;

6
drivers/vhost/vhost.h
View File

@ -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);
}