[PATCH RFC (resend) net-next 1/6] virtio-net: Remove the use the padded vnet_header structure

[Vladislav Yasevich]

We can replace the structure with a properly aligned size instead.
The current structure attempts to align on a 16 byte boundary, so
preserve it.

Signed-off-by: Vlad Yaseivch <vyase...@redhat.com>
---
 drivers/net/virtio_net.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b0d241d..2937a98 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -174,15 +174,20 @@ struct virtnet_info {
        u32 speed;
 };
 
-struct padded_vnet_hdr {
-       struct virtio_net_hdr_mrg_rxbuf hdr;
+static inline u8 padded_vnet_hdr(struct virtnet_info *vi)
+{
+       u8 hdr_len = vi->hdr_len;
+
        /*
         * hdr is in a separate sg buffer, and data sg buffer shares same page
         * with this header sg. This padding makes next sg 16 byte aligned
         * after the header.
         */
-       char padding[4];
-};
+       if (!vi->mergeable_rx_bufs)
+               hdr_len = __ALIGN_KERNEL_MASK(hdr_len, 15);
+
+       return hdr_len;
+}
 
 /* Converting between virtqueue no. and kernel tx/rx queue no.
  * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
@@ -289,10 +294,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
        hdr = skb_vnet_hdr(skb);
 
        hdr_len = vi->hdr_len;
-       if (vi->mergeable_rx_bufs)
-               hdr_padded_len = sizeof *hdr;
-       else
-               hdr_padded_len = sizeof(struct padded_vnet_hdr);
+       hdr_padded_len = padded_vnet_hdr(vi);
 
        memcpy(hdr, p, hdr_len);
 
@@ -840,7 +842,7 @@ static int add_recvbuf_big(struct virtnet_info *vi, struct 
receive_queue *rq,
        sg_set_buf(&rq->sg[0], p, vi->hdr_len);
 
        /* rq->sg[1] for data packet, from offset */
-       offset = sizeof(struct padded_vnet_hdr);
+       offset = padded_vnet_hdr(vi);
        sg_set_buf(&rq->sg[1], p + offset, PAGE_SIZE - offset);
 
        /* chain first in list head */
@@ -1790,8 +1792,8 @@ static int virtnet_reset(struct virtnet_info *vi, int 
curr_qp, int xdp_qp)
 
 static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 {
-       unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr);
        struct virtnet_info *vi = netdev_priv(dev);
+       unsigned long int max_sz = PAGE_SIZE - padded_vnet_hdr(vi);
        struct bpf_prog *old_prog;
        u16 xdp_qp = 0, curr_qp;
        int i, err;
-- 
2.7.4