Re: [RFC Optimizing veth xsk performance 09/10] veth: support zero copy for af xdp
From: Simon Horman <horms@kernel.org>
Date: 2023-08-04 21:05:48
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On Thu, Aug 03, 2023 at 10:04:35PM +0800, huangjie.albert wrote: ...
+static struct sk_buff *veth_build_skb_zerocopy(struct net_device *dev, struct xsk_buff_pool *pool,
+ struct xdp_desc *desc)
+{
+ struct veth_seg_info *seg_info;
+ struct sk_buff *skb;
+ struct page *page;
+ void *hard_start;
+ u32 len, ts;
+ void *buffer;
+ int headroom;
+ u64 addr;
+ u32 index;
+
+ addr = desc->addr;
+ len = desc->len;
+ buffer = xsk_buff_raw_get_data(pool, addr);
+ ts = pool->unaligned ? len : pool->chunk_size;
+
+ headroom = offset_in_page(buffer);
+
+ /* offset in umem pool buffer */
+ addr = buffer - pool->addrs;
+
+ /* get the page of the desc */
+ page = pool->umem->pgs[addr >> PAGE_SHIFT];
+
+ /* in order to avoid to get freed by kfree_skb */
+ get_page(page);
+
+ hard_start = page_to_virt(page);
+
+ skb = veth_build_skb(hard_start, headroom, len, ts);
+ seg_info = (struct veth_seg_info *)kmalloc(struct_size(seg_info, desc, MAX_SKB_FRAGS), GFP_KERNEL);There is no need to explicitly case the return value of kmalloc, as it returns void *. seg_info = kmalloc(struct_size(seg_info, desc, MAX_SKB_FRAGS), GFP_KERNEL); ...