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/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;