virtio/vsock: send credit update during setting SO_RCVLOWAT

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>

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index f75731396b7eff89183783ac32b6866c4ae66c91..ec20ecff85c7f470edce5e2537f85e3b9a1f6c35 100644 (file)
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -449,6 +449,7 @@ 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 ebb3ce63d64dac9fce2b87fabb2a93b61c499310..c82089dee0c831af449de8a6cc410e86b660fea3 100644 (file)
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -256,4 +256,5 @@ 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 e302c0e804d0f2ce6ef45aae51a2d2c5ee7c2c23..535701efc1e5cec874b8b94088020b1199c8b8c0 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 816725af281f388f7f21d60806670843e79b6fcc..54ba7316f8085d7e1f7335611b8f88d853342696 100644 (file)
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2264,8 +2264,13 @@ 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 af5bab1acee17deafec1062aecf0477164e42eed..f495b9e5186b2e965d96cc95141fa15f2abbdfc7 100644 (file)
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -537,6 +537,7 @@ 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 b35306dfcebed3e928859c719f04cbf07869dbb8..16ff976a86e3ed73adaa7c4141189eecbbb74abb 100644 (file)
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1690,6 +1690,36 @@ 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 0486401674117d65f465a2fb20c41075d19df76a..6dea6119f5b2812f104298498eeb9d880da7400e 100644 (file)
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -96,6 +96,7 @@ 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,
        },