vhost-net: flush outstanding DMAs on memory change

[~andy/linux] / drivers / vhost / net.c

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 1802ab662082ab9e741cd24be8b894f13e05b2ce..6a86deb39a7246f6dd2f7418e7fd3745f04277cd 100644 (file)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -83,6 +83,8 @@ struct vhost_net {
        /* Number of times zerocopy TX recently failed.
         * Protected by tx vq lock. */
        unsigned tx_zcopy_err;
+       /* Flush in progress. Protected by tx vq lock. */
+       bool tx_flush;
 };
 
 static void vhost_net_tx_packet(struct vhost_net *net)
@@ -101,7 +103,11 @@ static void vhost_net_tx_err(struct vhost_net *net)
 
 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 {
-       return net->tx_packets / 64 >= net->tx_zcopy_err;
+       /* TX flush waits for outstanding DMAs to be done.
+        * Don't start new DMAs.
+        */
+       return !net->tx_flush &&
+               net->tx_packets / 64 >= net->tx_zcopy_err;
 }
 
 static bool vhost_sock_zcopy(struct socket *sock)
@@ -679,6 +685,17 @@ static void vhost_net_flush(struct vhost_net *n)
 {
        vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
        vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
+       if (n->dev.vqs[VHOST_NET_VQ_TX].ubufs) {
+               mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+               n->tx_flush = true;
+               mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+               /* Wait for all lower device DMAs done. */
+               vhost_ubuf_put_and_wait(n->dev.vqs[VHOST_NET_VQ_TX].ubufs);
+               mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+               n->tx_flush = false;
+               kref_init(&n->dev.vqs[VHOST_NET_VQ_TX].ubufs->kref);
+               mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+       }
 }
 
 static int vhost_net_release(struct inode *inode, struct file *f)
@@ -686,18 +703,10 @@ static int vhost_net_release(struct inode *inode, struct file *f)
        struct vhost_net *n = f->private_data;
        struct socket *tx_sock;
        struct socket *rx_sock;
-       int i;
 
        vhost_net_stop(n, &tx_sock, &rx_sock);
        vhost_net_flush(n);
        vhost_dev_stop(&n->dev);
-       for (i = 0; i < n->dev.nvqs; ++i) {
-               /* Wait for all lower device DMAs done. */
-               if (n->dev.vqs[i].ubufs)
-                       vhost_ubuf_put_and_wait(n->dev.vqs[i].ubufs);
-
-               vhost_zerocopy_signal_used(n, &n->dev.vqs[i]);
-       }
        vhost_dev_cleanup(&n->dev, false);
        if (tx_sock)
                fput(tx_sock->file);
@@ -826,6 +835,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 
                n->tx_packets = 0;
                n->tx_zcopy_err = 0;
+               n->tx_flush = false;
        }
 
        mutex_unlock(&vq->mutex);