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Commit 5e18247b authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

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: default avatarMichael S. Tsirkin <mst@redhat.com>
parent fca540ab

drivers/vhost/net.c

+5 −4
Original line number Diff line number Diff line
@@ -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;

drivers/vhost/vhost.h

+3 −3
Original line number Diff line number Diff line
@@ -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);

}