wireguard: send/receive: use explicit unlikely branch instead of implicit coalescing

It's very unlikely that send will become true. It's nearly always false
between 0 and 120 seconds of a session, and in most cases becomes true
only between 120 and 121 seconds before becoming false again. So,
unlikely(send) is clearly the right option here.

What happened before was that we had this complex boolean expression
with multiple likely and unlikely clauses nested. Since this is
evaluated left-to-right anyway, the whole thing got converted to
unlikely. So, we can clean this up to better represent what's going on.

The generated code is the same.

Suggested-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c
index 2566e13a292dee09c7784d5e71832e252b248b7f..3bb5b9ae7cd15634df6f4700f223618e8f4b456b 100644 (file)
--- a/drivers/net/wireguard/receive.c
+++ b/drivers/net/wireguard/receive.c
@@ -226,21 +226,20 @@ void wg_packet_handshake_receive_worker(struct work_struct *work)
 static void keep_key_fresh(struct wg_peer *peer)
 {
        struct noise_keypair *keypair;
-       bool send = false;
+       bool send;
 
        if (peer->sent_lastminute_handshake)
                return;
 
        rcu_read_lock_bh();
        keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
-       if (likely(keypair && READ_ONCE(keypair->sending.is_valid)) &&
-           keypair->i_am_the_initiator &&
-           unlikely(wg_birthdate_has_expired(keypair->sending.birthdate,
-                       REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT)))
-               send = true;
+       send = keypair && READ_ONCE(keypair->sending.is_valid) &&
+              keypair->i_am_the_initiator &&
+              wg_birthdate_has_expired(keypair->sending.birthdate,
+                       REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT);
        rcu_read_unlock_bh();
 
-       if (send) {
+       if (unlikely(send)) {
                peer->sent_lastminute_handshake = true;
                wg_packet_send_queued_handshake_initiation(peer, false);
        }

diff --git a/drivers/net/wireguard/send.c b/drivers/net/wireguard/send.c
index dc3079e17c7fc6abef5d69853e9bc8adb5465a08..6687db69980351c6ba68bb5757626a7dbdbd0e56 100644 (file)
--- a/drivers/net/wireguard/send.c
+++ b/drivers/net/wireguard/send.c
@@ -124,20 +124,17 @@ void wg_packet_send_handshake_cookie(struct wg_device *wg,
 static void keep_key_fresh(struct wg_peer *peer)
 {
        struct noise_keypair *keypair;
-       bool send = false;
+       bool send;
 
        rcu_read_lock_bh();
        keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
-       if (likely(keypair && READ_ONCE(keypair->sending.is_valid)) &&
-           (unlikely(atomic64_read(&keypair->sending.counter.counter) >
-                     REKEY_AFTER_MESSAGES) ||
-            (keypair->i_am_the_initiator &&
-             unlikely(wg_birthdate_has_expired(keypair->sending.birthdate,
-                                               REKEY_AFTER_TIME)))))
-               send = true;
+       send = keypair && READ_ONCE(keypair->sending.is_valid) &&
+              (atomic64_read(&keypair->sending.counter.counter) > REKEY_AFTER_MESSAGES ||
+               (keypair->i_am_the_initiator &&
+                wg_birthdate_has_expired(keypair->sending.birthdate, REKEY_AFTER_TIME)));
        rcu_read_unlock_bh();
 
-       if (send)
+       if (unlikely(send))
                wg_packet_send_queued_handshake_initiation(peer, false);
 }