Commit b0727b0c authored by Paolo Abeni's avatar Paolo Abeni
Browse files

Merge branch 'virtio-fixes-for-tx-ring-sizing-and-resize-error-reporting' 

Laurent Vivier says:

====================
virtio: Fixes for TX ring sizing and resize error reporting

This patch series contains two fixes and a cleanup for the virtio subsystem.

The first patch fixes an error reporting bug in virtio_ring's
virtqueue_resize() function. Previously, errors from internal resize
helpers could be masked if the subsequent re-enabling of the virtqueue
succeeded. This patch restores the correct error propagation, ensuring that
callers of virtqueue_resize() are properly informed of underlying resize
failures.

The second patch does a cleanup of the use of '2+MAX_SKB_FRAGS'

The third patch addresses a reliability issue in virtio_net where the TX
ring size could be configured too small, potentially leading to
persistently stopped queues and degraded performance. It enforces a
minimum TX ring size to ensure there's always enough space for at least one
maximally-fragmented packet plus an additional slot.
====================

Link: https://patch.msgid.link/20250521092236.661410-1-lvivier@redhat.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parents 5177373c 24b2f5df

drivers/net/virtio_net.c

+10 −4
Original line number Diff line number Diff line
@@ -1104,7 +1104,7 @@ static bool tx_may_stop(struct virtnet_info *vi, 
	 * Since most packets only take 1 or 2 ring slots, stopping the queue

	 * early means 16 slots are typically wasted.

	 */

	if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {

	if (sq->vq->num_free < MAX_SKB_FRAGS + 2) {

		struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);



		netif_tx_stop_queue(txq);
@@ -1136,7 +1136,7 @@ static void check_sq_full_and_disable(struct virtnet_info *vi, 
		} else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {

			/* More just got used, free them then recheck. */

			free_old_xmit(sq, txq, false);

			if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {

			if (sq->vq->num_free >= MAX_SKB_FRAGS + 2) {

				netif_start_subqueue(dev, qnum);

				u64_stats_update_begin(&sq->stats.syncp);

				u64_stats_inc(&sq->stats.wake);
@@ -3021,7 +3021,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq, int budget) 
			free_old_xmit(sq, txq, !!budget);

		} while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));



		if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) {

		if (sq->vq->num_free >= MAX_SKB_FRAGS + 2) {

			if (netif_tx_queue_stopped(txq)) {

				u64_stats_update_begin(&sq->stats.syncp);

				u64_stats_inc(&sq->stats.wake);
@@ -3218,7 +3218,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) 
	else

		free_old_xmit(sq, txq, !!budget);



	if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) {

	if (sq->vq->num_free >= MAX_SKB_FRAGS + 2) {

		if (netif_tx_queue_stopped(txq)) {

			u64_stats_update_begin(&sq->stats.syncp);

			u64_stats_inc(&sq->stats.wake);
@@ -3504,6 +3504,12 @@ static int virtnet_tx_resize(struct virtnet_info *vi, struct send_queue *sq, 
{

	int qindex, err;



	if (ring_num <= MAX_SKB_FRAGS + 2) {

		netdev_err(vi->dev, "tx size (%d) cannot be smaller than %d\n",

			   ring_num, MAX_SKB_FRAGS + 2);

		return -EINVAL;

	}



	qindex = sq - vi->sq;



	virtnet_tx_pause(vi, sq);

drivers/virtio/virtio_ring.c

+6 −2
Original line number Diff line number Diff line
@@ -2797,7 +2797,7 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num, 
		     void (*recycle_done)(struct virtqueue *vq))

{

	struct vring_virtqueue *vq = to_vvq(_vq);

	int err;

	int err, err_reset;



	if (num > vq->vq.num_max)

		return -E2BIG;
@@ -2819,7 +2819,11 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num, 
	else

		err = virtqueue_resize_split(_vq, num);



	return virtqueue_enable_after_reset(_vq);

	err_reset = virtqueue_enable_after_reset(_vq);

	if (err_reset)

		return err_reset;



	return err;

}

EXPORT_SYMBOL_GPL(virtqueue_resize);