Commit d8b0c963 authored by Paolo Abeni's avatar Paolo Abeni
Browse files

Merge branch 'allocate-multiple-skbuffs-on-tx' 

Arseniy Krasnov says:

====================
allocate multiple skbuffs on tx

This adds small optimization for tx path: instead of allocating single
skbuff on every call to transport, allocate multiple skbuff's until
credit space allows, thus trying to send as much as possible data without
return to af_vsock.c.

Also this patchset includes second patch which adds check and return from
'virtio_transport_get_credit()' and 'virtio_transport_put_credit()' when
these functions are called with 0 argument. This is needed, because zero
argument makes both functions to behave as no-effect, but both of them
always tries to acquire spinlock. Moreover, first patch always calls
function 'virtio_transport_put_credit()' with zero argument in case of
successful packet transmission.
====================

Link: https://lore.kernel.org/r/b0d15942-65ba-3a32-ba8d-fed64332d8f6@sberdevices.ru


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parents 4cee0fb9 e3ec366e

net/vmw_vsock/virtio_transport_common.c

+49 −14
Original line number Diff line number Diff line
@@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, 
	const struct virtio_transport *t_ops;

	struct virtio_vsock_sock *vvs;

	u32 pkt_len = info->pkt_len;

	struct sk_buff *skb;

	u32 rest_len;

	int ret;



	info->type = virtio_transport_get_type(sk_vsock(vsk));
@@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, 


	vvs = vsk->trans;



	/* we can send less than pkt_len bytes */

	if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)

		pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;



	/* virtio_transport_get_credit might return less than pkt_len credit */

	pkt_len = virtio_transport_get_credit(vvs, pkt_len);
@@ -227,17 +224,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, 
	if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)

		return pkt_len;



	skb = virtio_transport_alloc_skb(info, pkt_len,

	rest_len = pkt_len;



	do {

		struct sk_buff *skb;

		size_t skb_len;



		skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);



		skb = virtio_transport_alloc_skb(info, skb_len,

						 src_cid, src_port,

						 dst_cid, dst_port);

		if (!skb) {

		virtio_transport_put_credit(vvs, pkt_len);

		return -ENOMEM;

			ret = -ENOMEM;

			break;

		}



		virtio_transport_inc_tx_pkt(vvs, skb);



	return t_ops->send_pkt(skb);

		ret = t_ops->send_pkt(skb);

		if (ret < 0)

			break;



		/* Both virtio and vhost 'send_pkt()' returns 'skb_len',

		 * but for reliability use 'ret' instead of 'skb_len'.

		 * Also if partial send happens (e.g. 'ret' != 'skb_len')

		 * somehow, we break this loop, but account such returned

		 * value in 'virtio_transport_put_credit()'.

		 */

		rest_len -= ret;



		if (WARN_ONCE(ret != skb_len,

			      "'send_pkt()' returns %i, but %zu expected\n",

			      ret, skb_len))

			break;

	} while (rest_len);



	virtio_transport_put_credit(vvs, rest_len);



	/* Return number of bytes, if any data has been sent. */

	if (rest_len != pkt_len)

		ret = pkt_len - rest_len;



	return ret;

}



static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
@@ -273,6 +302,9 @@ u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 credit) 
{

	u32 ret;



	if (!credit)

		return 0;



	spin_lock_bh(&vvs->tx_lock);

	ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);

	if (ret > credit)
@@ -286,6 +318,9 @@ EXPORT_SYMBOL_GPL(virtio_transport_get_credit); 


void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit)

{

	if (!credit)

		return;



	spin_lock_bh(&vvs->tx_lock);

	vvs->tx_cnt -= credit;

	spin_unlock_bh(&vvs->tx_lock);