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Message-Id: <4c424e0980420dfff194a9d1c8e66609b2fa6cba.1609837120.git.xuanzhuo@linux.alibaba.com>
Date: Tue, 5 Jan 2021 17:11:42 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: netdev@...r.kernel.org
Cc: dust.li@...ux.alibaba.com, tonylu@...ux.alibaba.com,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Björn Töpel <bjorn.topel@...el.com>,
Magnus Karlsson <magnus.karlsson@...el.com>,
Jonathan Lemon <jonathan.lemon@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
KP Singh <kpsingh@...nel.org>,
virtualization@...ts.linux-foundation.org (open list:VIRTIO CORE AND
NET DRIVERS), linux-kernel@...r.kernel.org (open list),
bpf@...r.kernel.org (open list:XDP SOCKETS (AF_XDP))
Subject: [PATCH netdev 4/5] xsk, virtio-net: prepare for support xsk
Split function free_old_xmit_skbs, add sub-function __free_old_xmit_ptr,
which is convenient to call with other statistical information, and
supports the parameter 'xsk_wakeup' required for processing xsk.
Use netif stop check as a function virtnet_sq_stop_check, which will be
used when adding xsk support.
Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
drivers/net/virtio_net.c | 95 ++++++++++++++++++++++++++----------------------
1 file changed, 52 insertions(+), 43 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index df38a9f..e744dce 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -263,6 +263,11 @@ struct padded_vnet_hdr {
char padding[4];
};
+static void __free_old_xmit_ptr(struct send_queue *sq, bool in_napi,
+ bool xsk_wakeup,
+ unsigned int *_packets, unsigned int *_bytes);
+static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi);
+
static bool is_xdp_frame(void *ptr)
{
return (unsigned long)ptr & VIRTIO_XDP_FLAG;
@@ -376,6 +381,37 @@ static void skb_xmit_done(struct virtqueue *vq)
netif_wake_subqueue(vi->dev, vq2txq(vq));
}
+static void virtnet_sq_stop_check(struct send_queue *sq, bool in_napi)
+{
+ struct virtnet_info *vi = sq->vq->vdev->priv;
+ struct net_device *dev = vi->dev;
+ int qnum = sq - vi->sq;
+
+ /* If running out of space, stop queue to avoid getting packets that we
+ * are then unable to transmit.
+ * An alternative would be to force queuing layer to requeue the skb by
+ * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
+ * returned in a normal path of operation: it means that driver is not
+ * maintaining the TX queue stop/start state properly, and causes
+ * the stack to do a non-trivial amount of useless work.
+ * 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) {
+ netif_stop_subqueue(dev, qnum);
+ if (!sq->napi.weight &&
+ unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
+ /* More just got used, free them then recheck. */
+ free_old_xmit_skbs(sq, in_napi);
+ if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) {
+ netif_start_subqueue(dev, qnum);
+ virtqueue_disable_cb(sq->vq);
+ }
+ }
+ }
+}
+
#define MRG_CTX_HEADER_SHIFT 22
static void *mergeable_len_to_ctx(unsigned int truesize,
unsigned int headroom)
@@ -543,13 +579,11 @@ static int virtnet_xdp_xmit(struct net_device *dev,
struct receive_queue *rq = vi->rq;
struct bpf_prog *xdp_prog;
struct send_queue *sq;
- unsigned int len;
int packets = 0;
int bytes = 0;
int drops = 0;
int kicks = 0;
int ret, err;
- void *ptr;
int i;
/* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
@@ -567,24 +601,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
goto out;
}
- /* Free up any pending old buffers before queueing new ones. */
- while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
- if (likely(is_xdp_frame(ptr))) {
- struct virtnet_xdp_type *xtype;
- struct xdp_frame *frame;
-
- xtype = ptr_to_xtype(ptr);
- frame = xtype_got_ptr(xtype);
- bytes += frame->len;
- xdp_return_frame(frame);
- } else {
- struct sk_buff *skb = ptr;
-
- bytes += skb->len;
- napi_consume_skb(skb, false);
- }
- packets++;
- }
+ __free_old_xmit_ptr(sq, false, true, &packets, &bytes);
for (i = 0; i < n; i++) {
struct xdp_frame *xdpf = frames[i];
@@ -1422,7 +1439,9 @@ static int virtnet_receive(struct receive_queue *rq, int budget,
return stats.packets;
}
-static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
+static void __free_old_xmit_ptr(struct send_queue *sq, bool in_napi,
+ bool xsk_wakeup,
+ unsigned int *_packets, unsigned int *_bytes)
{
unsigned int packets = 0;
unsigned int bytes = 0;
@@ -1456,6 +1475,17 @@ static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
packets++;
}
+ *_packets = packets;
+ *_bytes = bytes;
+}
+
+static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
+{
+ unsigned int packets = 0;
+ unsigned int bytes = 0;
+
+ __free_old_xmit_ptr(sq, in_napi, true, &packets, &bytes);
+
/* Avoid overhead when no packets have been processed
* happens when called speculatively from start_xmit.
*/
@@ -1672,28 +1702,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
nf_reset_ct(skb);
}
- /* If running out of space, stop queue to avoid getting packets that we
- * are then unable to transmit.
- * An alternative would be to force queuing layer to requeue the skb by
- * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
- * returned in a normal path of operation: it means that driver is not
- * maintaining the TX queue stop/start state properly, and causes
- * the stack to do a non-trivial amount of useless work.
- * 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) {
- netif_stop_subqueue(dev, qnum);
- if (!use_napi &&
- unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
- /* More just got used, free them then recheck. */
- free_old_xmit_skbs(sq, false);
- if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
- netif_start_subqueue(dev, qnum);
- virtqueue_disable_cb(sq->vq);
- }
- }
- }
+ virtnet_sq_stop_check(sq, false);
if (kick || netif_xmit_stopped(txq)) {
if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
--
1.8.3.1
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