From: Jason Wang <jasowang@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>, netdev@vger.kernel.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
"Jakub Kicinski" <kuba@kernel.org>,
"Björn Töpel" <bjorn@kernel.org>,
"Magnus Karlsson" <magnus.karlsson@intel.com>,
"Jonathan Lemon" <jonathan.lemon@gmail.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"KP Singh" <kpsingh@kernel.org>,
virtualization@lists.linux-foundation.org, bpf@vger.kernel.org,
"Dust Li" <dust.li@linux.alibaba.com>
Subject: Re: [PATCH net-next v3 3/8] virtio-net: xsk zero copy xmit setup
Date: Tue, 6 Apr 2021 12:27:14 +0800 [thread overview]
Message-ID: <97a147bc-f9b8-ce95-889d-274893fd0444@redhat.com> (raw)
In-Reply-To: <20210331071139.15473-4-xuanzhuo@linux.alibaba.com>
在 2021/3/31 下午3:11, Xuan Zhuo 写道:
> xsk is a high-performance packet receiving and sending technology.
>
> This patch implements the binding and unbinding operations of xsk and
> the virtio-net queue for xsk zero copy xmit.
>
> The xsk zero copy xmit depends on tx napi. So if tx napi is not opened,
> an error will be reported. And the entire operation is under the
> protection of rtnl_lock
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
> ---
> drivers/net/virtio_net.c | 66 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 66 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index bb4ea9dbc16b..4e25408a2b37 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -22,6 +22,7 @@
> #include <net/route.h>
> #include <net/xdp.h>
> #include <net/net_failover.h>
> +#include <net/xdp_sock_drv.h>
>
> static int napi_weight = NAPI_POLL_WEIGHT;
> module_param(napi_weight, int, 0444);
> @@ -133,6 +134,11 @@ struct send_queue {
> struct virtnet_sq_stats stats;
>
> struct napi_struct napi;
> +
> + struct {
> + /* xsk pool */
> + struct xsk_buff_pool __rcu *pool;
> + } xsk;
> };
>
> /* Internal representation of a receive virtqueue */
> @@ -2526,11 +2532,71 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
> return err;
> }
>
> +static int virtnet_xsk_pool_enable(struct net_device *dev,
> + struct xsk_buff_pool *pool,
> + u16 qid)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + struct send_queue *sq;
> + int ret = -EBUSY;
I'd rather move this under the check of xsk.pool.
> +
> + if (qid >= vi->curr_queue_pairs)
> + return -EINVAL;
> +
> + sq = &vi->sq[qid];
> +
> + /* xsk zerocopy depend on the tx napi */
Need more comments to explain why tx NAPI is required here.
And what's more important, tx NAPI could be enabled/disable via ethtool,
what if the NAPI is disabled after xsk is enabled?
> + if (!sq->napi.weight)
> + return -EPERM;
> +
> + rcu_read_lock();
> + if (rcu_dereference(sq->xsk.pool))
> + goto end;
Under what condition can we reach here?
> +
> + /* Here is already protected by rtnl_lock, so rcu_assign_pointer is
> + * safe.
> + */
> + rcu_assign_pointer(sq->xsk.pool, pool);
> + ret = 0;
> +end:
> + rcu_read_unlock();
> +
> + return ret;
> +}
> +
> +static int virtnet_xsk_pool_disable(struct net_device *dev, u16 qid)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + struct send_queue *sq;
> +
> + if (qid >= vi->curr_queue_pairs)
> + return -EINVAL;
> +
> + sq = &vi->sq[qid];
> +
> + /* Here is already protected by rtnl_lock, so rcu_assign_pointer is
> + * safe.
> + */
> + rcu_assign_pointer(sq->xsk.pool, NULL);
> +
> + synchronize_rcu(); /* Sync with the XSK wakeup and with NAPI. */
Since rtnl is held here, I guess it's better to use synchornize_net().
> +
> + return 0;
> +}
> +
> static int virtnet_xdp(struct net_device *dev, struct netdev_bpf *xdp)
> {
> switch (xdp->command) {
> case XDP_SETUP_PROG:
> return virtnet_xdp_set(dev, xdp->prog, xdp->extack);
> + case XDP_SETUP_XSK_POOL:
> + /* virtio net not use dma before call vring api */
> + xdp->xsk.check_dma = false;
I think it's better not open code things like this. How about introduce
new parameters in xp_assign_dev()?
> + if (xdp->xsk.pool)
> + return virtnet_xsk_pool_enable(dev, xdp->xsk.pool,
> + xdp->xsk.queue_id);
> + else
> + return virtnet_xsk_pool_disable(dev, xdp->xsk.queue_id);
> default:
> return -EINVAL;
> }
Thanks
next prev parent reply other threads:[~2021-04-06 4:27 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-31 7:11 [PATCH net-next v3 0/8] virtio-net support xdp socket zero copy xmit Xuan Zhuo
2021-03-31 7:11 ` [PATCH net-next v3 1/8] xsk: XDP_SETUP_XSK_POOL support option check_dma Xuan Zhuo
2021-03-31 7:11 ` [PATCH net-next v3 2/8] xsk: support get page by addr Xuan Zhuo
2021-03-31 7:11 ` [PATCH net-next v3 3/8] virtio-net: xsk zero copy xmit setup Xuan Zhuo
2021-04-06 4:27 ` Jason Wang [this message]
2021-04-07 10:02 ` Magnus Karlsson
2021-03-31 7:11 ` [PATCH net-next v3 4/8] virtio-net: xsk zero copy xmit implement wakeup and xmit Xuan Zhuo
2021-04-06 6:19 ` Jason Wang
2021-04-07 9:56 ` Magnus Karlsson
2021-03-31 7:11 ` [PATCH net-next v3 5/8] virtio-net: xsk zero copy xmit support xsk unaligned mode Xuan Zhuo
2021-04-06 6:55 ` Jason Wang
2021-03-31 7:11 ` [PATCH net-next v3 6/8] virtio-net: xsk zero copy xmit kick by threshold Xuan Zhuo
2021-04-06 6:59 ` Jason Wang
2021-03-31 7:11 ` [PATCH net-next v3 7/8] virtio-net: poll tx call xsk zerocopy xmit Xuan Zhuo
2021-04-06 7:03 ` Jason Wang
2021-03-31 7:11 ` [PATCH net-next v3 8/8] virtio-net: free old xmit handle xsk Xuan Zhuo
2021-04-06 7:16 ` Jason Wang
[not found] <1617780476.5300975-1-xuanzhuo@linux.alibaba.com>
2021-04-07 9:00 ` [PATCH net-next v3 3/8] virtio-net: xsk zero copy xmit setup Jason Wang
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