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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 15 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7820f3a7dd70..993da005e087 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -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;