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Commit 28b39bc7 authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

virtio-net: pack headroom into ctx for mergeable buffers 



Pack headroom into ctx - this way when we get a buffer we can figure out
the actual headroom that was allocated for the buffer. Will be helpful
to optimize switching between XDP and non-XDP modes which have different
headroom requirements.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 87646a34

drivers/net/virtio_net.c

+24 −5
Original line number Diff line number Diff line
@@ -270,6 +270,23 @@ static void skb_xmit_done(struct virtqueue *vq) 
		netif_wake_subqueue(vi->dev, vq2txq(vq));

}



#define MRG_CTX_HEADER_SHIFT 22

static void *mergeable_len_to_ctx(unsigned int truesize,

				  unsigned int headroom)

{

	return (void *)(unsigned long)((headroom << MRG_CTX_HEADER_SHIFT) | truesize);

}



static unsigned int mergeable_ctx_to_headroom(void *mrg_ctx)

{

	return (unsigned long)mrg_ctx >> MRG_CTX_HEADER_SHIFT;

}



static unsigned int mergeable_ctx_to_truesize(void *mrg_ctx)

{

	return (unsigned long)mrg_ctx & ((1 << MRG_CTX_HEADER_SHIFT) - 1);

}



/* Called from bottom half context */

static struct sk_buff *page_to_skb(struct virtnet_info *vi,

				   struct receive_queue *rq,
@@ -639,13 +656,14 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
	}

	rcu_read_unlock();



	if (unlikely(len > (unsigned long)ctx)) {

	truesize = mergeable_ctx_to_truesize(ctx);

	if (unlikely(len > truesize)) {

		pr_debug("%s: rx error: len %u exceeds truesize %lu\n",

			 dev->name, len, (unsigned long)ctx);

		dev->stats.rx_length_errors++;

		goto err_skb;

	}

	truesize = (unsigned long)ctx;



	head_skb = page_to_skb(vi, rq, page, offset, len, truesize);

	curr_skb = head_skb;
@@ -665,13 +683,14 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
		}



		page = virt_to_head_page(buf);

		if (unlikely(len > (unsigned long)ctx)) {



		truesize = mergeable_ctx_to_truesize(ctx);

		if (unlikely(len > truesize)) {

			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",

				 dev->name, len, (unsigned long)ctx);

			dev->stats.rx_length_errors++;

			goto err_skb;

		}

		truesize = (unsigned long)ctx;



		num_skb_frags = skb_shinfo(curr_skb)->nr_frags;

		if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
@@ -889,7 +908,7 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi, 


	buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;

	buf += headroom; /* advance address leaving hole at front of pkt */

	ctx = (void *)(unsigned long)len;

	ctx = mergeable_len_to_ctx(len, headroom);

	get_page(alloc_frag->page);

	alloc_frag->offset += len + headroom;

	hole = alloc_frag->size - alloc_frag->offset;