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net: cache skb_shinfo() in skb_try_coalesce()

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Compiler does not really know that skb_shinfo(to|from) are constants
in skb_try_coalesce(), lets cache their values to shrink code.

We might even take care of skb_zcopy() calls later.

$ size net/core/skbuff.o.before net/core/skbuff.o
   text	   data	    bss	    dec	    hex	filename
  40727	   1298	      0	  42025	   a429	net/core/skbuff.o.before
  40631	   1298	      0	  41929	   a3c9	net/core/skbuff.o

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-10-04 10:48:35 -07:00 committed by David S. Miller
parent e9b871ee09
commit c818fa9e28
1 changed files with 16 additions and 13 deletions
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29
net/core/skbuff.c
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@ -4767,6 +4767,7 @@ EXPORT_SYMBOL(kfree_skb_partial);
bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
bool *fragstolen, int *delta_truesize)
{
struct skb_shared_info *to_shinfo, *from_shinfo;
int i, delta, len = from->len;
*fragstolen = false;
@ -4781,7 +4782,9 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
return true;
}
if (skb_has_frag_list(to) || skb_has_frag_list(from))
to_shinfo = skb_shinfo(to);
from_shinfo = skb_shinfo(from);
if (to_shinfo->frag_list || from_shinfo->frag_list)
return false;
if (skb_zcopy(to) || skb_zcopy(from))
return false;
@ -4790,8 +4793,8 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
struct page *page;
unsigned int offset;
if (skb_shinfo(to)->nr_frags +
skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
if (to_shinfo->nr_frags +
from_shinfo->nr_frags >= MAX_SKB_FRAGS)
return false;
if (skb_head_is_locked(from))
@ -4802,12 +4805,12 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
page = virt_to_head_page(from->head);
offset = from->data - (unsigned char *)page_address(page);
skb_fill_page_desc(to, skb_shinfo(to)->nr_frags,
skb_fill_page_desc(to, to_shinfo->nr_frags,
page, offset, skb_headlen(from));
*fragstolen = true;
} else {
if (skb_shinfo(to)->nr_frags +
skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS)
if (to_shinfo->nr_frags +
from_shinfo->nr_frags > MAX_SKB_FRAGS)
return false;
delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
@ -4815,19 +4818,19 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
WARN_ON_ONCE(delta < len);
memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags,
skb_shinfo(from)->frags,
skb_shinfo(from)->nr_frags * sizeof(skb_frag_t));
skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags;
memcpy(to_shinfo->frags + to_shinfo->nr_frags,
from_shinfo->frags,
from_shinfo->nr_frags * sizeof(skb_frag_t));
to_shinfo->nr_frags += from_shinfo->nr_frags;
if (!skb_cloned(from))
skb_shinfo(from)->nr_frags = 0;
from_shinfo->nr_frags = 0;
/* if the skb is not cloned this does nothing
* since we set nr_frags to 0.
*/
for (i = 0; i < skb_shinfo(from)->nr_frags; i++)
skb_frag_ref(from, i);
for (i = 0; i < from_shinfo->nr_frags; i++)
__skb_frag_ref(&from_shinfo->frags[i]);
to->truesize += delta;
to->len += len;