netdev - [PATCH] netfilter: use likely() in xt_info_rdlock

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Message-ID: <49FAB4FC.6040907@cosmosbay.com>
Date:	Fri, 01 May 2009 10:38:20 +0200
From:	Eric Dumazet <dada1@...mosbay.com>
To:	David Miller <davem@...emloft.net>
CC:	shemminger@...tta.com, kaber@...sh.net,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH] netfilter: use likely()  in xt_info_rdlock_bh()

David Miller a écrit :
> From: Linus Torvalds <torvalds@...ux-foundation.org>
> Date: Tue, 28 Apr 2009 09:55:32 -0700 (PDT)
> 
>> On Tue, 28 Apr 2009, Linus Torvalds wrote:
>>> Ack. 
>>>
>>> It could do with the update from Eric about how non-current CPU writelocks 
>>> only require preemp-disable around get_counters() (and then the 
>>> local_bh_disable() only around the current-CPU case).
>> Btw, regardless, that's an incremental improvement, and does not negate 
>> the "Ack" part.
> 
> I've applied this, thanks everyone!

Small followup on this one, since the likely() were forgotten.
(I trimmed down CCed list, which was insane)

It makes a difference on my x86_32 machine, gcc-4.4.0

Thank you

[PATCH] netfilter: use likely() in xt_info_rdlock_bh()

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
---

diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index 1b2e435..c9efe03 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -472,7 +472,7 @@ static inline void xt_info_rdlock_bh(void)
 
 	local_bh_disable();
 	lock = &__get_cpu_var(xt_info_locks);
-	if (!lock->readers++)
+	if (likely(!lock->readers++))
 		spin_lock(&lock->lock);
 }
 
@@ -480,7 +480,7 @@ static inline void xt_info_rdunlock_bh(void)
 {
 	struct xt_info_lock *lock = &__get_cpu_var(xt_info_locks);
 
-	if (!--lock->readers)
+	if (likely(!--lock->readers))
 		spin_unlock(&lock->lock);
 	local_bh_enable();
 }

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