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Commit c818fa9e authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: cache skb_shinfo() in skb_try_coalesce() 



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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e9b871ee

net/core/skbuff.c

+16 −13
Original line number Diff line number Diff line
@@ -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;