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net: netdev_alloc_skb() use build_skb()
netdev_alloc_skb() is used by networks driver in their RX path to allocate an skb to receive an incoming frame. With recent skb->head_frag infrastructure, it makes sense to change netdev_alloc_skb() to use build_skb() and a frag allocator. This permits a zero copy splice(socket->pipe), and better GRO or TCP coalescing. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -293,6 +293,12 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size)
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}
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EXPORT_SYMBOL(build_skb);
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struct netdev_alloc_cache {
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struct page *page;
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unsigned int offset;
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};
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static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
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/**
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* __netdev_alloc_skb - allocate an skbuff for rx on a specific device
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* @dev: network device to receive on
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@ -310,8 +316,32 @@ struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
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unsigned int length, gfp_t gfp_mask)
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{
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struct sk_buff *skb;
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unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) +
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SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
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skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
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if (fragsz <= PAGE_SIZE && !(gfp_mask & __GFP_WAIT)) {
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struct netdev_alloc_cache *nc;
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void *data = NULL;
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nc = &get_cpu_var(netdev_alloc_cache);
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if (!nc->page) {
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refill: nc->page = alloc_page(gfp_mask);
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nc->offset = 0;
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}
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if (likely(nc->page)) {
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if (nc->offset + fragsz > PAGE_SIZE) {
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put_page(nc->page);
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goto refill;
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}
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data = page_address(nc->page) + nc->offset;
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nc->offset += fragsz;
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get_page(nc->page);
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}
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put_cpu_var(netdev_alloc_cache);
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skb = data ? build_skb(data, fragsz) : NULL;
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} else {
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skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
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}
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if (likely(skb)) {
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skb_reserve(skb, NET_SKB_PAD);
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skb->dev = dev;
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