[PATCH net-next V2 06/11] tuntap: split out XDP logic

Jason Wang
2018-09-12T03:17:04Z

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@redhat.com>
---
drivers/net/tun.c | 88 +++++++++++++++++++++++++++--------------------
1 file changed, 51 insertions(+), 37 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 946c6148ed75..14fe94098180 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1636,14 +1636,14 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile,
}

static struct sk_buff *__tun_build_skb(struct page_frag *alloc_frag, char *buf,
- int buflen, int len, int pad, int delta)
+ int buflen, int len, int pad)
{
struct sk_buff *skb = build_skb(buf, buflen);

if (!skb)
return ERR_PTR(-ENOMEM);

- skb_reserve(skb, pad - delta);
+ skb_reserve(skb, pad);
skb_put(skb, len);

get_page(alloc_frag->page);
@@ -1652,6 +1652,39 @@ static struct sk_buff *__tun_build_skb(struct page_frag *alloc_frag, char *buf,
return skb;
}

+static int tun_xdp_act(struct tun_struct *tun, struct bpf_prog *xdp_prog,
+ struct xdp_buff *xdp, u32 act)
+{
+ int err;
+
+ switch (act) {
+ case XDP_REDIRECT:
+ err = xdp_do_redirect(tun->dev, xdp, xdp_prog);
+ xdp_do_flush_map();
+ if (err)
+ return err;
+ break;
+ case XDP_TX:
+ err = tun_xdp_tx(tun->dev, xdp);
+ if (err < 0)
+ return err;
+ break;
+ case XDP_PASS:
+ 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:
+ this_cpu_inc(tun->pcpu_stats->rx_dropped);
+ break;
+ }
+
+ return act;
+}
+
static struct sk_buff *tun_build_skb(struct tun_struct *tun,
struct tun_file *tfile,
struct iov_iter *from,
@@ -1661,10 +1694,10 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
struct page_frag *alloc_frag = &current->task_frag;
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);
@@ -1690,7 +1723,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
*/
if (hdr->gso_type || !xdp_prog) {
*skb_xdp = 1;
- return __tun_build_skb(alloc_frag, buf, buflen, len, pad, delta);
+ return __tun_build_skb(alloc_frag, buf, buflen, len, pad);
}

*skb_xdp = 0;
@@ -1698,9 +1731,8 @@ 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;
@@ -1708,49 +1740,31 @@ 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:
- get_page(alloc_frag->page);
- alloc_frag->offset += buflen;
- err = xdp_do_redirect(tun->dev, &xdp, xdp_prog);
- xdp_do_flush_map();
- if (err)
- goto err_redirect;
- goto out;
- case XDP_TX:
+ act = bpf_prog_run_xdp(xdp_prog, &xdp);
+ if (act == XDP_REDIRECT || act == XDP_TX) {
get_page(alloc_frag->page);
alloc_frag->offset += buflen;
- if (tun_xdp_tx(tun->dev, &xdp) < 0)
- goto err_redirect;
- 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:
- goto out;
}
+ err = tun_xdp_act(tun, xdp_prog, &xdp, act);
+ if (err < 0)
+ goto err_xdp;
+ if (err != XDP_PASS)
+ goto out;
+
+ pad = xdp.data - xdp.data_hard_start;
+ len = xdp.data_end - xdp.data;
}
rcu_read_unlock();
local_bh_enable();

- return __tun_build_skb(alloc_frag, buf, buflen, len, pad, delta);
+ return __tun_build_skb(alloc_frag, buf, buflen, len, pad);

-err_redirect:
+err_xdp:
put_page(alloc_frag->page);
out:
rcu_read_unlock();
local_bh_enable();
- this_cpu_inc(tun->pcpu_stats->rx_dropped);
return NULL;
}

--
2.17.1