net: make GRO aware of skb->head_frag GRO can check if skb to be merged has its skb->head mapped to a page fragment, instead of a kmalloc() area. We 'upgrade' skb->head as a fragment in itself This avoids the frag_list fallback, and permits to build true GRO skb (one sk_buff and up to 16 fragments), using less memory. This reduces number of cache misses when user makes its copy, since a single sk_buff is fetched. This is a followup of patch "net: allow skb->head to be a page fragment" Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Maciej Żenczykowski <maze@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Matt Carlson <mcarlson@broadcom.com> Cc: Michael Chan <mchan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index e0b70e9..7f377fb 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h
@@ -1509,6 +1509,8 @@ /* Free the skb? */ int free; +#define NAPI_GRO_FREE 1 +#define NAPI_GRO_FREE_STOLEN_HEAD 2 }; #define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 9d28a22..2c75e98 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h
@@ -561,6 +561,7 @@ extern void kfree_skb(struct sk_buff *skb); extern void consume_skb(struct sk_buff *skb); extern void __kfree_skb(struct sk_buff *skb); +extern struct kmem_cache *skbuff_head_cache; extern struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int fclone, int node); extern struct sk_buff *build_skb(void *data, unsigned int frag_size);
diff --git a/net/core/dev.c b/net/core/dev.c index 501f3cc..a2be59f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c
@@ -3546,7 +3546,10 @@ break; case GRO_MERGED_FREE: - consume_skb(skb); + if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD) + kmem_cache_free(skbuff_head_cache, skb); + else + __kfree_skb(skb); break; case GRO_HELD:
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index effa75d..09cc386 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c
@@ -69,7 +69,7 @@ #include <trace/events/skb.h> #include <linux/highmem.h> -static struct kmem_cache *skbuff_head_cache __read_mostly; +struct kmem_cache *skbuff_head_cache __read_mostly; static struct kmem_cache *skbuff_fclone_cache __read_mostly; static void sock_pipe_buf_release(struct pipe_inode_info *pipe, @@ -2901,6 +2901,31 @@ NAPI_GRO_CB(skb)->free = 1; goto done; + } else if (skb->head_frag) { + int nr_frags = pinfo->nr_frags; + skb_frag_t *frag = pinfo->frags + nr_frags; + struct page *page = virt_to_head_page(skb->head); + unsigned int first_size = headlen - offset; + unsigned int first_offset; + + if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS) + return -E2BIG; + + first_offset = skb->data - + (unsigned char *)page_address(page) + + offset; + + pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags; + + frag->page.p = page; + frag->page_offset = first_offset; + skb_frag_size_set(frag, first_size); + + memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags); + /* We dont need to clear skbinfo->nr_frags here */ + + NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD; + goto done; } else if (skb_gro_len(p) != pinfo->gso_size) return -E2BIG;