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Subject[PATCH 4.17 060/101] virtio_net: split XDP_TX kick and XDP_REDIRECT map flushing
Date
4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jesper Dangaard Brouer <brouer@redhat.com>

[ Upstream commit 2471c75efed32529698c26da499954f0253cb401 ]

The driver was combining XDP_TX virtqueue_kick and XDP_REDIRECT
map flushing (xdp_do_flush_map). This is suboptimal, these two
flush operations should be kept separate.

The suboptimal behavior was introduced in commit 9267c430c6b6
("virtio-net: add missing virtqueue kick when flushing packets").

Fixes: 9267c430c6b6 ("virtio-net: add missing virtqueue kick when flushing packets")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/virtio_net.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -50,6 +50,10 @@ module_param(napi_tx, bool, 0644);
/* Amount of XDP headroom to prepend to packets for use by xdp_adjust_head */
#define VIRTIO_XDP_HEADROOM 256

+/* Separating two types of XDP xmit */
+#define VIRTIO_XDP_TX BIT(0)
+#define VIRTIO_XDP_REDIR BIT(1)
+
/* RX packet size EWMA. The average packet size is used to determine the packet
* buffer size when refilling RX rings. As the entire RX ring may be refilled
* at once, the weight is chosen so that the EWMA will be insensitive to short-
@@ -547,7 +551,7 @@ static struct sk_buff *receive_small(str
struct receive_queue *rq,
void *buf, void *ctx,
unsigned int len,
- bool *xdp_xmit)
+ unsigned int *xdp_xmit)
{
struct sk_buff *skb;
struct bpf_prog *xdp_prog;
@@ -615,14 +619,14 @@ static struct sk_buff *receive_small(str
trace_xdp_exception(vi->dev, xdp_prog, act);
goto err_xdp;
}
- *xdp_xmit = true;
+ *xdp_xmit |= VIRTIO_XDP_TX;
rcu_read_unlock();
goto xdp_xmit;
case XDP_REDIRECT:
err = xdp_do_redirect(dev, &xdp, xdp_prog);
if (err)
goto err_xdp;
- *xdp_xmit = true;
+ *xdp_xmit |= VIRTIO_XDP_REDIR;
rcu_read_unlock();
goto xdp_xmit;
default:
@@ -684,7 +688,7 @@ static struct sk_buff *receive_mergeable
void *buf,
void *ctx,
unsigned int len,
- bool *xdp_xmit)
+ unsigned int *xdp_xmit)
{
struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
@@ -772,7 +776,7 @@ static struct sk_buff *receive_mergeable
put_page(xdp_page);
goto err_xdp;
}
- *xdp_xmit = true;
+ *xdp_xmit |= VIRTIO_XDP_REDIR;
if (unlikely(xdp_page != page))
put_page(page);
rcu_read_unlock();
@@ -784,7 +788,7 @@ static struct sk_buff *receive_mergeable
put_page(xdp_page);
goto err_xdp;
}
- *xdp_xmit = true;
+ *xdp_xmit |= VIRTIO_XDP_TX;
if (unlikely(xdp_page != page))
put_page(page);
rcu_read_unlock();
@@ -893,7 +897,8 @@ xdp_xmit:
}

static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
- void *buf, unsigned int len, void **ctx, bool *xdp_xmit)
+ void *buf, unsigned int len, void **ctx,
+ unsigned int *xdp_xmit)
{
struct net_device *dev = vi->dev;
struct sk_buff *skb;
@@ -1186,7 +1191,8 @@ static void refill_work(struct work_stru
}
}

-static int virtnet_receive(struct receive_queue *rq, int budget, bool *xdp_xmit)
+static int virtnet_receive(struct receive_queue *rq, int budget,
+ unsigned int *xdp_xmit)
{
struct virtnet_info *vi = rq->vq->vdev->priv;
unsigned int len, received = 0, bytes = 0;
@@ -1275,7 +1281,7 @@ static int virtnet_poll(struct napi_stru
struct virtnet_info *vi = rq->vq->vdev->priv;
struct send_queue *sq;
unsigned int received, qp;
- bool xdp_xmit = false;
+ unsigned int xdp_xmit = 0;

virtnet_poll_cleantx(rq);

@@ -1285,12 +1291,14 @@ static int virtnet_poll(struct napi_stru
if (received < budget)
virtqueue_napi_complete(napi, rq->vq, received);

- if (xdp_xmit) {
+ if (xdp_xmit & VIRTIO_XDP_REDIR)
+ xdp_do_flush_map();
+
+ if (xdp_xmit & VIRTIO_XDP_TX) {
qp = vi->curr_queue_pairs - vi->xdp_queue_pairs +
smp_processor_id();
sq = &vi->sq[qp];
virtqueue_kick(sq->vq);
- xdp_do_flush_map();
}

return received;

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