diff mbox series

[RFC,v3,2/3] virtio/vsock: send credit update during setting SO_RCVLOWAT

Message ID 20231122180510.2297075-3-avkrasnov@salutedevices.com (mailing list archive)
State New, archived
Headers show
Series send credit update during setting SO_RCVLOWAT | expand

Commit Message

Arseniy Krasnov Nov. 22, 2023, 6:05 p.m. UTC 
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
SO_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()'.

Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
---
 Changelog:
 v1 -> v2:
  * Update commit message by removing 'This patch adds XXX' manner.
  * Do not initialize 'send_update' variable - set it directly during
    first usage.

 drivers/vhost/vsock.c                   |  2 ++
 include/linux/virtio_vsock.h            |  1 +
 net/vmw_vsock/virtio_transport.c        |  2 ++
 net/vmw_vsock/virtio_transport_common.c | 28 +++++++++++++++++++++++++
 net/vmw_vsock/vsock_loopback.c          |  2 ++
 5 files changed, 35 insertions(+)

Comments

Stefano Garzarella Nov. 29, 2023, 9:01 a.m. UTC | #1 
On Wed, Nov 22, 2023 at 09:05:09PM +0300, Arseniy Krasnov wrote:
>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
>SO_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()'.
>
>Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
>---
> Changelog:
> v1 -> v2:
>  * Update commit message by removing 'This patch adds XXX' manner.
>  * Do not initialize 'send_update' variable - set it directly during
>    first usage.
>
> drivers/vhost/vsock.c                   |  2 ++
> include/linux/virtio_vsock.h            |  1 +
> net/vmw_vsock/virtio_transport.c        |  2 ++
> net/vmw_vsock/virtio_transport_common.c | 28 +++++++++++++++++++++++++
> net/vmw_vsock/vsock_loopback.c          |  2 ++
> 5 files changed, 35 insertions(+)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index f75731396b7e..ecfa5c11f5ee 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -451,6 +451,8 @@ static struct virtio_transport vhost_transport = {
> 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
>
> 		.read_skb = virtio_transport_read_skb,
>+
>+		.set_rcvlowat             = virtio_transport_set_rcvlowat

Since now we don't set it anymore in the callback, what about following
the notify_* callbacks and rename it in `notify_set_rcvlowat`?

Eventually I think we can rename it in the previous patch.

> 	},
>
> 	.send_pkt = vhost_transport_send_pkt,
>diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>index ebb3ce63d64d..97dc1bebc69c 100644
>--- 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_set_rcvlowat(struct vsock_sock *vsk, int val);
> #endif /* _LINUX_VIRTIO_VSOCK_H */
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index af5bab1acee1..cf3431189d0c 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -539,6 +539,8 @@ static struct virtio_transport virtio_transport = {
> 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
>
> 		.read_skb = virtio_transport_read_skb,
>+
>+		.set_rcvlowat             = virtio_transport_set_rcvlowat
> 	},
>
> 	.send_pkt = virtio_transport_send_pkt,
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index f6dc896bf44c..4acee21b4350 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -1684,6 +1684,34 @@ 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_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.
>+	 */

Let's try to use at least the full 80 characters so we can reduce the
lines in this comment block.

>+	send_update = vvs->rx_bytes < val;
>+
>+	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_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 048640167411..388c157f6633 100644
>--- a/net/vmw_vsock/vsock_loopback.c
>+++ b/net/vmw_vsock/vsock_loopback.c
>@@ -98,6 +98,8 @@ static struct virtio_transport loopback_transport = {
> 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
>
> 		.read_skb = virtio_transport_read_skb,
>+
>+		.set_rcvlowat             = virtio_transport_set_rcvlowat
> 	},
>
> 	.send_pkt = vsock_loopback_send_pkt,
>-- 
>2.25.1
>
diff mbox series

Patch

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index f75731396b7e..ecfa5c11f5ee 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -451,6 +451,8 @@  static struct virtio_transport vhost_transport = {
 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
 
 		.read_skb = virtio_transport_read_skb,
+
+		.set_rcvlowat             = virtio_transport_set_rcvlowat
 	},
 
 	.send_pkt = vhost_transport_send_pkt,
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index ebb3ce63d64d..97dc1bebc69c 100644
--- 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_set_rcvlowat(struct vsock_sock *vsk, int val);
 #endif /* _LINUX_VIRTIO_VSOCK_H */
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index af5bab1acee1..cf3431189d0c 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -539,6 +539,8 @@  static struct virtio_transport virtio_transport = {
 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
 
 		.read_skb = virtio_transport_read_skb,
+
+		.set_rcvlowat             = virtio_transport_set_rcvlowat
 	},
 
 	.send_pkt = virtio_transport_send_pkt,
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index f6dc896bf44c..4acee21b4350 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1684,6 +1684,34 @@  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_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.
+	 */
+	send_update = vvs->rx_bytes < val;
+
+	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_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 048640167411..388c157f6633 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -98,6 +98,8 @@  static struct virtio_transport loopback_transport = {
 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
 
 		.read_skb = virtio_transport_read_skb,
+
+		.set_rcvlowat             = virtio_transport_set_rcvlowat
 	},
 
 	.send_pkt = vsock_loopback_send_pkt,