On Thu, Sep 06, 2018 at 12:05:21PM +0800, Jason Wang wrote:
> This patch split out XDP logic into a single function. This make it to
> be reused by XDP batching path in the following patch.
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/net/tun.c | 84 ++++++++++++++++++++++++++++-------------------
> 1 file changed, 51 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 389aa0727cc6..21b125020b3b 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1635,6 +1635,44 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile,
> return true;
> }
>
> +static u32 tun_do_xdp(struct tun_struct *tun,
> + struct tun_file *tfile,
> + struct bpf_prog *xdp_prog,
> + struct xdp_buff *xdp,
> + int *err)
> +{
> + u32 act = bpf_prog_run_xdp(xdp_prog, xdp);
> +
> + switch (act) {
> + case XDP_REDIRECT:
> + *err = xdp_do_redirect(tun->dev, xdp, xdp_prog);
> + xdp_do_flush_map();
> + if (*err)
> + break;
> + goto out;
> + case XDP_TX:
> + *err = tun_xdp_tx(tun->dev, xdp);
> + if (*err < 0)
> + break;
> + *err = 0;
> + goto out;
> + case XDP_PASS:
> + goto out;
Do we need goto? why not just return?
> + default:
> + bpf_warn_invalid_xdp_action(act);
> + /* fall through */
> + case XDP_ABORTED:
> + trace_xdp_exception(tun->dev, xdp_prog, act);
> + /* fall through */
> + case XDP_DROP:
> + break;
> + }
> +
> + put_page(virt_to_head_page(xdp->data_hard_start));
put here because caller does get_page :( Not pretty.
I'd move this out to the caller.
> +out:
> + return act;
How about combining err and act? err is < 0 XDP_PASS is > 0.
No need for pointers then.
> +}
> +
> static struct sk_buff *tun_build_skb(struct tun_struct *tun,
> struct tun_file *tfile,
> struct iov_iter *from,
> @@ -1645,10 +1683,10 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
> struct sk_buff *skb = NULL;
> struct bpf_prog *xdp_prog;
> int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
> - unsigned int delta = 0;
> char *buf;
> size_t copied;
> - int err, pad = TUN_RX_PAD;
> + int pad = TUN_RX_PAD;
> + int err = 0;
>
> rcu_read_lock();
> xdp_prog = rcu_dereference(tun->xdp_prog);
> @@ -1685,9 +1723,8 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
> local_bh_disable();
> rcu_read_lock();
> xdp_prog = rcu_dereference(tun->xdp_prog);
> - if (xdp_prog && !*skb_xdp) {
> + if (xdp_prog) {
> struct xdp_buff xdp;
> - void *orig_data;
> u32 act;
>
> xdp.data_hard_start = buf;
> @@ -1695,33 +1732,14 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
> xdp_set_data_meta_invalid(&xdp);
> xdp.data_end = xdp.data + len;
> xdp.rxq = &tfile->xdp_rxq;
> - orig_data = xdp.data;
> - act = bpf_prog_run_xdp(xdp_prog, &xdp);
> -
> - switch (act) {
> - case XDP_REDIRECT:
> - err = xdp_do_redirect(tun->dev, &xdp, xdp_prog);
> - xdp_do_flush_map();
> - if (err)
> - goto err_xdp;
> - goto out;
> - case XDP_TX:
> - if (tun_xdp_tx(tun->dev, &xdp) < 0)
> - goto err_xdp;
> - goto out;
> - case XDP_PASS:
> - delta = orig_data - xdp.data;
> - len = xdp.data_end - xdp.data;
> - break;
> - default:
> - bpf_warn_invalid_xdp_action(act);
> - /* fall through */
> - case XDP_ABORTED:
> - trace_xdp_exception(tun->dev, xdp_prog, act);
> - /* fall through */
> - case XDP_DROP:
> + act = tun_do_xdp(tun, tfile, xdp_prog, &xdp, &err);
> + if (err)
> goto err_xdp;
> - }
> + if (act != XDP_PASS)
> + goto out;
likely?
> +
> + pad = xdp.data - xdp.data_hard_start;
> + len = xdp.data_end - xdp.data;
> }
> rcu_read_unlock();
> local_bh_enable();
> @@ -1729,18 +1747,18 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
> build:
> skb = build_skb(buf, buflen);
> if (!skb) {
> + put_page(alloc_frag->page);
> skb = ERR_PTR(-ENOMEM);
> goto out;
> }
>
> - skb_reserve(skb, pad - delta);
> + skb_reserve(skb, pad);
> skb_put(skb, len);
>
> return skb;
>
> err_xdp:
> - alloc_frag->offset -= buflen;
> - put_page(alloc_frag->page);
> + this_cpu_inc(tun->pcpu_stats->rx_dropped);
This fixes bug in previous patch which dropped it. OK :)
> out:
> rcu_read_unlock();
> local_bh_enable();
> --
> 2.17.1
