virtio/vsock: send credit update during setting SO_RCVLOWAT

[ Upstream commit 0fe1798968115488c0c02f4633032a015b1faf97 ]

Send credit update message when SO_RCVLOWAT is updated and it is bigger
than number of bytes in rx queue. It is needed, because 'poll()' will
wait until number of bytes in rx queue will be not smaller than
O_RCVLOWAT, so kick sender to send more data. Otherwise mutual hungup
for tx/rx is possible: sender waits for free space and receiver is
waiting data in 'poll()'.

Rename 'set_rcvlowat' callback to 'notify_set_rcvlowat' and set
'sk->sk_rcvlowat' only in one place (i.e. 'vsock_set_rcvlowat'), so the
transport doesn't need to do it.

Fixes: b89d882dc9fc ("vsock/virtio: reduce credit update messages")
Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 817d377a3f360f6cd87f4da1d02debaac4d34545..61255855d4906d9c52c5a58845abcd4171fc0c12 100644 (file)
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -438,6 +438,7 @@ static struct virtio_transport vhost_transport = {
                .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
                .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
                .notify_buffer_size       = virtio_transport_notify_buffer_size,
+               .notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 
                .read_skb = virtio_transport_read_skb,
        },

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index c58453699ee9878168f97a4037894944b02e6008..fbf30721bac9e5be63290dcd855dd95f4a12cf87 100644 (file)
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -246,4 +246,5 @@ void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
 void virtio_transport_deliver_tap_pkt(struct sk_buff *skb);
 int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *list);
 int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t read_actor);
+int virtio_transport_notify_set_rcvlowat(struct vsock_sock *vsk, int val);
 #endif /* _LINUX_VIRTIO_VSOCK_H */

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index b01cf9ac243715489bacd8a66756905b275da9a2..dc3cb16835b637bc88798e50d0938f52bf7684f4 100644 (file)
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -137,7 +137,6 @@ struct vsock_transport {
        u64 (*stream_rcvhiwat)(struct vsock_sock *);
        bool (*stream_is_active)(struct vsock_sock *);
        bool (*stream_allow)(u32 cid, u32 port);
-       int (*set_rcvlowat)(struct vsock_sock *vsk, int val);
 
        /* SEQ_PACKET. */
        ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
@@ -168,6 +167,7 @@ struct vsock_transport {
                struct vsock_transport_send_notify_data *);
        /* sk_lock held by the caller */
        void (*notify_buffer_size)(struct vsock_sock *, u64 *);
+       int (*notify_set_rcvlowat)(struct vsock_sock *vsk, int val);
 
        /* Shutdown. */
        int (*shutdown)(struct vsock_sock *, int);

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index ccd8cefeea7ba07d8188da16e995c13cc4d5d8a8..4afb6a541cf38cacb84244819a7806ffeaea770f 100644 (file)
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2214,8 +2214,13 @@ static int vsock_set_rcvlowat(struct sock *sk, int val)
 
        transport = vsk->transport;
 
-       if (transport && transport->set_rcvlowat)
-               return transport->set_rcvlowat(vsk, val);
+       if (transport && transport->notify_set_rcvlowat) {
+               int err;
+
+               err = transport->notify_set_rcvlowat(vsk, val);
+               if (err)
+                       return err;
+       }
 
        WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
        return 0;

diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index 7cb1a9d2cdb4f8bf669c15a5227acfaca5f11c45..e2157e3872177056adc1f565a71f7d306ac95803 100644 (file)
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -816,7 +816,7 @@ int hvs_notify_send_post_enqueue(struct vsock_sock *vsk, ssize_t written,
 }
 
 static
-int hvs_set_rcvlowat(struct vsock_sock *vsk, int val)
+int hvs_notify_set_rcvlowat(struct vsock_sock *vsk, int val)
 {
        return -EOPNOTSUPP;
 }
@@ -856,7 +856,7 @@ static struct vsock_transport hvs_transport = {
        .notify_send_pre_enqueue  = hvs_notify_send_pre_enqueue,
        .notify_send_post_enqueue = hvs_notify_send_post_enqueue,
 
-       .set_rcvlowat             = hvs_set_rcvlowat
+       .notify_set_rcvlowat      = hvs_notify_set_rcvlowat
 };
 
 static bool hvs_check_transport(struct vsock_sock *vsk)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index b80bf681327bd31c48a7b3022a35faf32a009e5b..a64bf601b480d7cdcbeb896e3f1a149f0997116c 100644 (file)
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -457,6 +457,7 @@ static struct virtio_transport virtio_transport = {
                .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
                .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
                .notify_buffer_size       = virtio_transport_notify_buffer_size,
+               .notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 
                .read_skb = virtio_transport_read_skb,
        },

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 34a6d5e64ff2b0f630ab552fa3a9d7e364752c0c..e87fd9480acdac0b4de7cd6aeccbbe9f1f1fce10 100644 (file)
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1526,6 +1526,36 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto
 }
 EXPORT_SYMBOL_GPL(virtio_transport_read_skb);
 
+int virtio_transport_notify_set_rcvlowat(struct vsock_sock *vsk, int val)
+{
+       struct virtio_vsock_sock *vvs = vsk->trans;
+       bool send_update;
+
+       spin_lock_bh(&vvs->rx_lock);
+
+       /* If number of available bytes is less than new SO_RCVLOWAT value,
+        * kick sender to send more data, because sender may sleep in its
+        * 'send()' syscall waiting for enough space at our side. Also
+        * don't send credit update when peer already knows actual value -
+        * such transmission will be useless.
+        */
+       send_update = (vvs->rx_bytes < val) &&
+                     (vvs->fwd_cnt != vvs->last_fwd_cnt);
+
+       spin_unlock_bh(&vvs->rx_lock);
+
+       if (send_update) {
+               int err;
+
+               err = virtio_transport_send_credit_update(vsk);
+               if (err < 0)
+                       return err;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_set_rcvlowat);
+
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Asias He");
 MODULE_DESCRIPTION("common code for virtio vsock");

diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 5c6360df1f313739aa3726580156c4d004c7011d..0ce65d0a4a44ffa1641ab80b467a7fb8a4fe0046 100644 (file)
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -90,6 +90,7 @@ static struct virtio_transport loopback_transport = {
                .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
                .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
                .notify_buffer_size       = virtio_transport_notify_buffer_size,
+               .notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 
                .read_skb = virtio_transport_read_skb,
        },