2015-08-13 18:03:31

by Sasha Levin

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 <[email protected]>
---
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

2015-08-13 18:46:22

by Tom Herbert

Subject: Re: [PATCH] net: allow sleeping when modifying store_rps_map

On Thu, Aug 13, 2015 at 11:03 AM, Sasha Levin <[email protected]> wrote:
> 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 <[email protected]>
> ---
> 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
>

Thanks Sasha!

Acked-by: Tom Herbert <[email protected]>

2015-08-14 04:56:19

by David Miller

Subject: Re: [PATCH] net: allow sleeping when modifying store_rps_map

From: Sasha Levin <[email protected]>
Date: Thu, 13 Aug 2015 14:03:16 -0400

> 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 <[email protected]>

Applied, thanks.