linux-kernel - [PATCH] net: allow sleeping when modifying store_rps

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Date:	Thu, 13 Aug 2015 14:03:16 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	tom@...bertland.com, davem@...emloft.net
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] net: allow sleeping when modifying store_rps_map

Commit 10e4ea751 ("net: Fix race condition in store_rps_map") has moved the
manipulation of the rps_needed jump label under a spinlock. Since changing
the state of a jump label may sleep this is incorrect and causes warnings
during runtime.

Make rps_map_lock a mutex to allow sleeping under it.

Fixes: 10e4ea751 ("net: Fix race condition in store_rps_map")
Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 net/core/net-sysfs.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 39ec694..b279077 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -689,7 +689,7 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
 	struct rps_map *old_map, *map;
 	cpumask_var_t mask;
 	int err, cpu, i;
-	static DEFINE_SPINLOCK(rps_map_lock);
+	static DEFINE_MUTEX(rps_map_mutex);
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
@@ -722,9 +722,9 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
 		map = NULL;
 	}
 
-	spin_lock(&rps_map_lock);
+	mutex_lock(&rps_map_mutex);
 	old_map = rcu_dereference_protected(queue->rps_map,
-					    lockdep_is_held(&rps_map_lock));
+					    mutex_is_locked(&rps_map_mutex));
 	rcu_assign_pointer(queue->rps_map, map);
 
 	if (map)
@@ -732,7 +732,7 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
 	if (old_map)
 		static_key_slow_dec(&rps_needed);
 
-	spin_unlock(&rps_map_lock);
+	mutex_unlock(&rps_map_mutex);
 
 	if (old_map)
 		kfree_rcu(old_map, rcu);
-- 
1.7.10.4

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