ixgbe: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb

{__,}napi_alloc_skb() allocates and reserves additional NET_SKB_PAD
+ NET_IP_ALIGN for any skb.
OTOH, ixgbe_construct_skb_zc() currently allocates and reserves
additional `xdp->data - xdp->data_hard_start`, which is
XDP_PACKET_HEADROOM for XSK frames.
There's no need for that at all as the frame is post-XDP and will
go only to the networking stack core.
Pass the size of the actual data only to __napi_alloc_skb() and
don't reserve anything. This will give enough headroom for stack
processing.

Fixes: d0bcacd0a130 ("ixgbe: add AF_XDP zero-copy Rx support")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
index 5447bfb318383284ca0294409a64acc755b234c3..80078762ed24e8549527800f188624fe449d9579 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
@@ -214,13 +214,11 @@ static struct sk_buff *ixgbe_construct_skb_zc(struct ixgbe_ring *rx_ring,
        struct sk_buff *skb;
 
        /* allocate a skb to store the frags */
-       skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
-                              xdp->data_end - xdp->data_hard_start,
+       skb = __napi_alloc_skb(&rx_ring->q_vector->napi, datasize,
                               GFP_ATOMIC | __GFP_NOWARN);
        if (unlikely(!skb))
                return NULL;
 
-       skb_reserve(skb, xdp->data - xdp->data_hard_start);
        memcpy(__skb_put(skb, datasize), xdp->data, datasize);
        if (metasize)
                skb_metadata_set(skb, metasize);