tuntap: split out XDP logic

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>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 946c6148ed75fa8a56150538a7ca0c1742f24eac..14fe94098180ddcf4b75580e45c0e7aa0fbfd5f9 100644 (file)
--- 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;
 }