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Commit 7b7fc97a authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: optimize some skb_shinfo(skb) uses 



Compiler doesn't know skb_shinfo(skb) pointer is usually constant.

By using a temporary variable, we help generating smaller code.

For example, tcp_init_nondata_skb() is inlined after this patch.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84b9cd63

net/ipv4/tcp_output.c

+21 −15
Original line number Diff line number Diff line
@@ -363,15 +363,17 @@ static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, 
 */

static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)

{

	struct skb_shared_info *shinfo = skb_shinfo(skb);



	skb->ip_summed = CHECKSUM_PARTIAL;

	skb->csum = 0;



	TCP_SKB_CB(skb)->tcp_flags = flags;

	TCP_SKB_CB(skb)->sacked = 0;



	skb_shinfo(skb)->gso_segs = 1;

	skb_shinfo(skb)->gso_size = 0;

	skb_shinfo(skb)->gso_type = 0;

	shinfo->gso_segs = 1;

	shinfo->gso_size = 0;

	shinfo->gso_type = 0;



	TCP_SKB_CB(skb)->seq = seq;

	if (flags & (TCPHDR_SYN | TCPHDR_FIN))
@@ -986,6 +988,8 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 
static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,

				 unsigned int mss_now)

{

	struct skb_shared_info *shinfo = skb_shinfo(skb);



	/* Make sure we own this skb before messing gso_size/gso_segs */

	WARN_ON_ONCE(skb_cloned(skb));
@@ -993,13 +997,13 @@ static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, 
		/* Avoid the costly divide in the normal

		 * non-TSO case.

		 */

		skb_shinfo(skb)->gso_segs = 1;

		skb_shinfo(skb)->gso_size = 0;

		skb_shinfo(skb)->gso_type = 0;

		shinfo->gso_segs = 1;

		shinfo->gso_size = 0;

		shinfo->gso_type = 0;

	} else {

		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now);

		skb_shinfo(skb)->gso_size = mss_now;

		skb_shinfo(skb)->gso_type = sk->sk_gso_type;

		shinfo->gso_segs = DIV_ROUND_UP(skb->len, mss_now);

		shinfo->gso_size = mss_now;

		shinfo->gso_type = sk->sk_gso_type;

	}

}
@@ -1146,6 +1150,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 
 */

static void __pskb_trim_head(struct sk_buff *skb, int len)

{

	struct skb_shared_info *shinfo;

	int i, k, eat;



	eat = min_t(int, len, skb_headlen(skb));
@@ -1157,23 +1162,24 @@ static void __pskb_trim_head(struct sk_buff *skb, int len) 
	}

	eat = len;

	k = 0;

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {

		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);

	shinfo = skb_shinfo(skb);

	for (i = 0; i < shinfo->nr_frags; i++) {

		int size = skb_frag_size(&shinfo->frags[i]);



		if (size <= eat) {

			skb_frag_unref(skb, i);

			eat -= size;

		} else {

			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];

			shinfo->frags[k] = shinfo->frags[i];

			if (eat) {

				skb_shinfo(skb)->frags[k].page_offset += eat;

				skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);

				shinfo->frags[k].page_offset += eat;

				skb_frag_size_sub(&shinfo->frags[k], eat);

				eat = 0;

			}

			k++;

		}

	}

	skb_shinfo(skb)->nr_frags = k;

	shinfo->nr_frags = k;



	skb_reset_tail_pointer(skb);

	skb->data_len -= len;