tcp: remove some dead code

Now all skbs in write queue do not contain any payload in skb->head,
we can remove some dead code.

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

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d039663..fedbe84 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1530,7 +1530,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *buff;
-       int nsize, old_factor;
+       int old_factor;
        long limit;
        int nlen;
        u8 flags;
@@ -1538,9 +1538,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
        if (WARN_ON(len > skb->len))
                return -EINVAL;
 
-       nsize = skb_headlen(skb) - len;
-       if (nsize < 0)
-               nsize = 0;
+       DEBUG_NET_WARN_ON_ONCE(skb_headlen(skb));
 
        /* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb.
         * We need some allowance to not penalize applications setting small
@@ -1560,7 +1558,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
                return -ENOMEM;
 
        /* Get a new skb... force flag on. */
-       buff = tcp_stream_alloc_skb(sk, nsize, gfp, true);
+       buff = tcp_stream_alloc_skb(sk, 0, gfp, true);
        if (!buff)
                return -ENOMEM; /* We'll just try again later. */
        skb_copy_decrypted(buff, skb);
@@ -1568,7 +1566,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
 
        sk_wmem_queued_add(sk, buff->truesize);
        sk_mem_charge(sk, buff->truesize);
-       nlen = skb->len - len - nsize;
+       nlen = skb->len - len;
        buff->truesize += nlen;
        skb->truesize -= nlen;
 
@@ -1626,13 +1624,7 @@ static int __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));
-       if (eat) {
-               __skb_pull(skb, eat);
-               len -= eat;
-               if (!len)
-                       return 0;
-       }
+       DEBUG_NET_WARN_ON_ONCE(skb_headlen(skb));
        eat = len;
        k = 0;
        shinfo = skb_shinfo(skb);
@@ -1671,12 +1663,10 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
 
        TCP_SKB_CB(skb)->seq += len;
 
-       if (delta_truesize) {
-               skb->truesize      -= delta_truesize;
-               sk_wmem_queued_add(sk, -delta_truesize);
-               if (!skb_zcopy_pure(skb))
-                       sk_mem_uncharge(sk, delta_truesize);
-       }
+       skb->truesize      -= delta_truesize;
+       sk_wmem_queued_add(sk, -delta_truesize);
+       if (!skb_zcopy_pure(skb))
+               sk_mem_uncharge(sk, delta_truesize);
 
        /* Any change of skb->len requires recalculation of tso factor. */
        if (tcp_skb_pcount(skb) > 1)
@@ -2126,9 +2116,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
        u8 flags;
 
        /* All of a TSO frame must be composed of paged data.  */
-       if (skb->len != skb->data_len)
-               return tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE,
-                                   skb, len, mss_now, gfp);
+       DEBUG_NET_WARN_ON_ONCE(skb->len != skb->data_len);
 
        buff = tcp_stream_alloc_skb(sk, 0, gfp, true);
        if (unlikely(!buff))
@@ -2487,12 +2475,8 @@ static int tcp_mtu_probe(struct sock *sk)
                } else {
                        TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags &
                                                   ~(TCPHDR_FIN|TCPHDR_PSH);
-                       if (!skb_shinfo(skb)->nr_frags) {
-                               skb_pull(skb, copy);
-                       } else {
-                               __pskb_trim_head(skb, copy);
-                               tcp_set_skb_tso_segs(skb, mss_now);
-                       }
+                       __pskb_trim_head(skb, copy);
+                       tcp_set_skb_tso_segs(skb, mss_now);
                        TCP_SKB_CB(skb)->seq += copy;
                }