From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 6 May 2020 15:33:06 -0600 Subject: [PATCH] wireguard: send/receive: use explicit unlikely branch instead of implicit coalescing commit 243f2148937adc72bcaaa590d482d599c936efde upstream. 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 Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller Signed-off-by: Jason A. Donenfeld --- drivers/net/wireguard/receive.c | 13 ++++++------- drivers/net/wireguard/send.c | 15 ++++++--------- 2 files changed, 12 insertions(+), 16 deletions(-) --- a/drivers/net/wireguard/receive.c +++ b/drivers/net/wireguard/receive.c @@ -226,21 +226,20 @@ void wg_packet_handshake_receive_worker( 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); } --- a/drivers/net/wireguard/send.c +++ b/drivers/net/wireguard/send.c @@ -124,20 +124,17 @@ void wg_packet_send_handshake_cookie(str 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); }