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From: Nicholas Mc Guire <der.herr@hofr.at>
To: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	Pedro Roque <roque@di.fc.ul.pt>,
	Peter Zijlstra <peterz@infradead.org>,
	netdev@vger.kernel.org
Subject: [PATCH] rebalance locks by converting write_lock_bh to write_lock+local_bh_disable
Date: Fri, 22 Nov 2013 00:54:02 +0100	[thread overview]
Message-ID: <20131121235402.GA11774@opentech.at> (raw)

>From 2c8e669b691b825c0ed2a02bd7a698d8ed5c6d29 Mon Sep 17 00:00:00 2001
From: Nicholas Mc Guire <der.herr@hofr.at>
Date: Thu, 21 Nov 2013 18:22:55 -0500
Subject: [PATCH] rebalance locks by converting write_lock_bh to write_lock+local_bh_disable
 

 in __neigh_event_send write_lock_bh(&neigh->lock) is implicitly balanced by
 write_unlock(&neigh->lock)+local_bh_disable() - while this is equivalent with
 respect to the effective low level locking primitives it breaks balancing
 in the locking api. This makes automatic lock-checking trigger false 
 positives, creates an implicit dependency between *_lock_bh and *_lock 
 functions as well as making the extremly simply locking of net core even
 easier to understand.

 The api inbalance was introduced in:
 commit cd28ca0a3dd17c68d24b839602a0e6268ad28b5d
 Author: Eric Dumazet <eric.dumazet@gmail.com>
 This patch just rebalances the lock api

 No change of functionality

Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
---
 net/core/neighbour.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ca15f32..d681c75 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -966,7 +966,8 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
 	int rc;
 	bool immediate_probe = false;
 
-	write_lock_bh(&neigh->lock);
+	local_bh_disable();
+	write_lock(&neigh->lock);
 
 	rc = 0;
 	if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE))
-- 
1.7.2.5

             reply	other threads:[~2013-11-22  0:01 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-21 23:54 Nicholas Mc Guire [this message]
2013-11-23 22:39 ` [PATCH] rebalance locks by converting write_lock_bh to write_lock+local_bh_disable David Miller
2013-11-23 23:58   ` Nicholas Mc Guire
2013-11-25  9:40     ` [PATCH] rebalance locks by converting write_lock_bh towrite_lock+local_bh_disable David Laight
2013-11-25 10:37       ` Nicholas Mc Guire

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