ipv4: gso: send_check() & segment() cleanups

inet_gso_segment() and inet_gso_send_check() are called by
skb_mac_gso_segment() under rcu lock, no need to use
rcu_read_lock() / rcu_read_unlock()

Avoid calling ip_hdr() twice per function.

We can use ip_send_check() helper.

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

1 files changed, 11 insertions, 13 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 35913fb77dc8..4f8cd4fc451d 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1254,20 +1254,19 @@ static int inet_gso_send_check(struct sk_buff *skb)
         if (ihl < sizeof(*iph))
                 goto out;
 
+        proto = iph->protocol;
+
+        /* Warning: after this point, iph might be no longer valid */
         if (unlikely(!pskb_may_pull(skb, ihl)))
                 goto out;
-
         __skb_pull(skb, ihl);
+
         skb_reset_transport_header(skb);
-        iph = ip_hdr(skb);
-        proto = iph->protocol;
         err = -EPROTONOSUPPORT;
 
-        rcu_read_lock();
         ops = rcu_dereference(inet_offloads[proto]);
         if (likely(ops && ops->callbacks.gso_send_check))
                 err = ops->callbacks.gso_send_check(skb);
-        rcu_read_unlock();
 
 out:
         return err;
@@ -1305,23 +1304,23 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
         if (ihl < sizeof(*iph))
                 goto out;
 
+        id = ntohs(iph->id);
+        proto = iph->protocol;
+
+        /* Warning: after this point, iph might be no longer valid */
         if (unlikely(!pskb_may_pull(skb, ihl)))
                 goto out;
+        __skb_pull(skb, ihl);
 
         tunnel = !!skb->encapsulation;
 
-        __skb_pull(skb, ihl);
         skb_reset_transport_header(skb);
-        iph = ip_hdr(skb);
-        id = ntohs(iph->id);
-        proto = iph->protocol;
+
         segs = ERR_PTR(-EPROTONOSUPPORT);
 
-        rcu_read_lock();
         ops = rcu_dereference(inet_offloads[proto]);
         if (likely(ops && ops->callbacks.gso_segment))
                 segs = ops->callbacks.gso_segment(skb, features);
-        rcu_read_unlock();
 
         if (IS_ERR_OR_NULL(segs))
                 goto out;
@@ -1339,8 +1338,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
                         iph->id = htons(id++);
                 }
                 iph->tot_len = htons(skb->len - skb->mac_len);
-                iph->check = 0;
-                iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
+                ip_send_check(iph);
         } while ((skb = skb->next));
 
 out: