mptcp: optimize release_cb for the common case

The mptcp release callback checks several flags in atomic
context, but only MPTCP_CLEAN_UNA can be up frequently.

Reorganize the code to avoid multiple conditionals in the
most common scenarios.

Additional clarify a related comment.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 0cbea3b6d0a4254d522b056434ea59895f5c8f81..2a9335ce5df11c748c376eec85f9515fd3f0537f 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3092,15 +3092,17 @@ static void mptcp_release_cb(struct sock *sk)
                spin_lock_bh(&sk->sk_lock.slock);
        }
 
-       /* be sure to set the current sk state before tacking actions
-        * depending on sk_state
-        */
-       if (__test_and_clear_bit(MPTCP_CONNECTED, &msk->cb_flags))
-               __mptcp_set_connected(sk);
        if (__test_and_clear_bit(MPTCP_CLEAN_UNA, &msk->cb_flags))
                __mptcp_clean_una_wakeup(sk);
-       if (__test_and_clear_bit(MPTCP_ERROR_REPORT, &msk->cb_flags))
-               __mptcp_error_report(sk);
+       if (unlikely(&msk->cb_flags)) {
+               /* be sure to set the current sk state before tacking actions
+                * depending on sk_state, that is processing MPTCP_ERROR_REPORT
+                */
+               if (__test_and_clear_bit(MPTCP_CONNECTED, &msk->cb_flags))
+                       __mptcp_set_connected(sk);
+               if (__test_and_clear_bit(MPTCP_ERROR_REPORT, &msk->cb_flags))
+                       __mptcp_error_report(sk);
+       }
 
        __mptcp_update_rmem(sk);
 }