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authorArseniy Krasnov <avkrasnov@salutedevices.com>2023-12-14 15:52:28 +0300
committerDavid S. Miller <davem@davemloft.net>2023-12-15 13:37:35 +0300
commit93b80887668226180ea5f5349cc728ca6dc700ab (patch)
treee27164f79784c1b98c0d923d72f4defc1ea3684a
parentbb7403655b3c3eb245d0ee330047cd3e20b3c4af (diff)
downloadlinux-93b80887668226180ea5f5349cc728ca6dc700ab.tar.xz
virtio/vsock: fix logic which reduces credit update messages
Add one more condition for sending credit update during dequeue from stream socket: when number of bytes in the rx queue is smaller than SO_RCVLOWAT value of the socket. This is actual for non-default value of SO_RCVLOWAT (e.g. not 1) - idea is to "kick" peer to continue data transmission, because we need at least SO_RCVLOWAT bytes in our rx queue to wake up user for reading data (in corner case it is also possible to stuck both tx and rx sides, this is why 'Fixes' is used). 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>
-rw-r--r--net/vmw_vsock/virtio_transport_common.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 6df246b53260..b35306dfcebe 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -557,6 +557,8 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
struct virtio_vsock_sock *vvs = vsk->trans;
size_t bytes, total = 0;
struct sk_buff *skb;
+ u32 fwd_cnt_delta;
+ bool low_rx_bytes;
int err = -EFAULT;
u32 free_space;
@@ -600,7 +602,10 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
}
}
- free_space = vvs->buf_alloc - (vvs->fwd_cnt - vvs->last_fwd_cnt);
+ fwd_cnt_delta = vvs->fwd_cnt - vvs->last_fwd_cnt;
+ free_space = vvs->buf_alloc - fwd_cnt_delta;
+ low_rx_bytes = (vvs->rx_bytes <
+ sock_rcvlowat(sk_vsock(vsk), 0, INT_MAX));
spin_unlock_bh(&vvs->rx_lock);
@@ -610,9 +615,11 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
* too high causes extra messages. Too low causes transmitter
* stalls. As stalls are in theory more expensive than extra
* messages, we set the limit to a high value. TODO: experiment
- * with different values.
+ * with different values. Also send credit update message when
+ * number of bytes in rx queue is not enough to wake up reader.
*/
- if (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
+ if (fwd_cnt_delta &&
+ (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE || low_rx_bytes))
virtio_transport_send_credit_update(vsk);
return total;