Thread (82 messages) 82 messages, 3 authors, 2022-07-18
STALE1427d
Revisions (5)
  1. v10 [diff vs current]
  2. v11 current
  3. v12 [diff vs current]
  4. v13 [diff vs current]
  5. v14 [diff vs current]

[PATCH v11 39/40] virtio_net: support tx queue resize

From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Date: 2022-06-29 07:01:59
Also in: bpf, kvm, linux-remoteproc, linux-s390, linux-um, platform-driver-x86, virtualization
Subsystem: networking drivers, the rest, virtio net driver · Maintainers: Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, "Michael S. Tsirkin", Jason Wang

This patch implements the resize function of the tx queues.
Based on this function, it is possible to modify the ring num of the
queue.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 48 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 6ab16fd193e5..fd358462f802 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -135,6 +135,9 @@ struct send_queue {
 	struct virtnet_sq_stats stats;
 
 	struct napi_struct napi;
+
+	/* Record whether sq is in reset state. */
+	bool reset;
 };
 
 /* Internal representation of a receive virtqueue */
@@ -279,6 +282,7 @@ struct padded_vnet_hdr {
 };
 
 static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
+static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
 
 static bool is_xdp_frame(void *ptr)
 {
@@ -1603,6 +1607,11 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
 		return;
 
 	if (__netif_tx_trylock(txq)) {
+		if (READ_ONCE(sq->reset)) {
+			__netif_tx_unlock(txq);
+			return;
+		}
+
 		do {
 			virtqueue_disable_cb(sq->vq);
 			free_old_xmit_skbs(sq, true);
@@ -1868,6 +1877,45 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
 	return err;
 }
 
+static int virtnet_tx_resize(struct virtnet_info *vi,
+			     struct send_queue *sq, u32 ring_num)
+{
+	struct netdev_queue *txq;
+	int err, qindex;
+
+	qindex = sq - vi->sq;
+
+	virtnet_napi_tx_disable(&sq->napi);
+
+	txq = netdev_get_tx_queue(vi->dev, qindex);
+
+	/* 1. wait all ximt complete
+	 * 2. fix the race of netif_stop_subqueue() vs netif_start_subqueue()
+	 */
+	__netif_tx_lock_bh(txq);
+
+	/* Prevent rx poll from accessing sq. */
+	WRITE_ONCE(sq->reset, true);
+
+	/* Prevent the upper layer from trying to send packets. */
+	netif_stop_subqueue(vi->dev, qindex);
+
+	__netif_tx_unlock_bh(txq);
+
+	err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
+	if (err)
+		netdev_err(vi->dev, "resize tx fail: tx queue index: %d err: %d\n", qindex, err);
+
+	/* Memory barrier before set reset and start subqueue. */
+	smp_mb();
+
+	WRITE_ONCE(sq->reset, false);
+	netif_tx_wake_queue(txq);
+
+	virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
+	return err;
+}
+
 /*
  * Send command via the control virtqueue and check status.  Commands
  * supported by the hypervisor, as indicated by feature bits, should
-- 
2.31.0
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help