From 28b39bc7c57e7920b0cbba3d79ba0f134e0f76f0 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 19 Jul 2017 16:54:46 +0800 Subject: [PATCH] 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: Jason Wang Signed-off-by: David S. Miller --- drivers/net/virtio_net.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 99830167ea2f..3223a36ad9a8 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -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;