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

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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>
This commit is contained in:
Jason A. Donenfeld 2020-05-06 15:33:06 -06:00 committed by David S. Miller
parent 4fed818ef5
commit 243f214893
2 changed files with 12 additions and 16 deletions
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13
drivers/net/wireguard/receive.c
View file

@ -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);
}

15
drivers/net/wireguard/send.c
View file

@ -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);
}