[PATCH v2 bpf-next 2/2] net: xdp: introduce xdp_build_skb_from_frame utility routine

[Lorenzo Bianconi]

Introduce xdp_build_skb_from_frame utility routine to build the skb
from xdp_frame. Respect to __xdp_build_skb_from_frame,
xdp_build_skb_from_frame will allocate the skb object. Rely on
xdp_build_skb_from_frame in veth driver.
Introduce missing xdp metadata support in veth_xdp_rcv_one routine.
Add missing metadata support in veth_xdp_rcv_one().

Reviewed-by: Toshiaki Makita <toshiaki.maki...@gmail.com>
Acked-by: Jesper Dangaard Brouer <bro...@redhat.com>
Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 drivers/net/veth.c | 18 +++---------------
 include/net/xdp.h  |  2 ++
 net/core/xdp.c     | 15 +++++++++++++++
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 99caae7d1641..6e03b619c93c 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -567,16 +567,10 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq 
*rq,
                                        struct veth_xdp_tx_bq *bq,
                                        struct veth_stats *stats)
 {
-       void *hard_start = frame->data - frame->headroom;
-       int len = frame->len, delta = 0;
        struct xdp_frame orig_frame;
        struct bpf_prog *xdp_prog;
-       unsigned int headroom;
        struct sk_buff *skb;
 
-       /* bpf_xdp_adjust_head() assures BPF cannot access xdp_frame area */
-       hard_start -= sizeof(struct xdp_frame);
-
        rcu_read_lock();
        xdp_prog = rcu_dereference(rq->xdp_prog);
        if (likely(xdp_prog)) {
@@ -590,8 +584,8 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,
 
                switch (act) {
                case XDP_PASS:
-                       delta = frame->data - xdp.data;
-                       len = xdp.data_end - xdp.data;
+                       if (xdp_update_frame_from_buff(&xdp, frame))
+                               goto err_xdp;
                        break;
                case XDP_TX:
                        orig_frame = *frame;
@@ -629,18 +623,12 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq 
*rq,
        }
        rcu_read_unlock();
 
-       headroom = sizeof(struct xdp_frame) + frame->headroom - delta;
-       skb = veth_build_skb(hard_start, headroom, len, frame->frame_sz);
+       skb = xdp_build_skb_from_frame(frame, rq->dev);
        if (!skb) {
                xdp_return_frame(frame);
                stats->rx_drops++;
-               goto err;
        }
 
-       xdp_release_frame(frame);
-       xdp_scrub_frame(frame);
-       skb->protocol = eth_type_trans(skb, rq->dev);
-err:
        return skb;
 err_xdp:
        rcu_read_unlock();
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 689206dee6de..c4bfdc9a8b79 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -167,6 +167,8 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct 
xdp_buff *xdp);
 struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
                                           struct sk_buff *skb,
                                           struct net_device *dev);
+struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+                                        struct net_device *dev);
 
 static inline
 void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
diff --git a/net/core/xdp.c b/net/core/xdp.c
index aeb09ed0704c..0d2630a35c3e 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -557,3 +557,18 @@ struct sk_buff *__xdp_build_skb_from_frame(struct 
xdp_frame *xdpf,
        return skb;
 }
 EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);
+
+struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+                                        struct net_device *dev)
+{
+       struct sk_buff *skb;
+
+       skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
+       if (unlikely(!skb))
+               return NULL;
+
+       memset(skb, 0, offsetof(struct sk_buff, tail));
+
+       return __xdp_build_skb_from_frame(xdpf, skb, dev);
+}
+EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);
-- 
2.29.2