[PATCH]: suspicious unlikely usage in tcp_transmit_skb()

[Hua Zhong <hzhong@gmail.com>]

Hi,

I am developing a profiling tool to check if likely/unlikely usages are wise. I find that the following one is always a miss:

      # Hit    # miss Function:Filename@Line
!         0     50505 tcp_transmit_skb():net/ipv4/tcp_output.c@468

There is a chance that my tool is buggy, but I just want to confirm with you whether this does look suspicious and what your opinion is.

Signed-off-by: Hua Zhong <hzhong@gmail.com>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a28ae59..743016b 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -465,7 +465,7 @@ #define SYSCTL_FLAG_SACK    0x4
        TCP_INC_STATS(TCP_MIB_OUTSEGS);
 
        err = icsk->icsk_af_ops->queue_xmit(skb, 0);
-       if (unlikely(err <= 0))
+       if (likely(err <= 0))
                return err;
 
        tcp_enter_cwr(sk);