Patchwork net: Fix locking bug in netif_set_xps_queue

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Submitter Alexander Duyck
Date Feb. 22, 2013, 4:38 p.m.
Message ID <20130222163806.7590.98066.stgit@ahduyck-cp1.jf.intel.com>
Download mbox | patch
Permalink /patch/222557/
State Accepted
Delegated to: David Miller
Headers show

Comments

Alexander Duyck - Feb. 22, 2013, 4:38 p.m.
Smatch found a locking bug in netif_set_xps_queue in which we were not
releasing the lock in the case of an allocation failure.

This change corrects that so that we release the xps_map_mutex before
returning -ENOMEM in the case of an allocation failure.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
 net/core/dev.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)


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David Miller - Feb. 22, 2013, 8:14 p.m.
From: Alexander Duyck <alexander.h.duyck@intel.com>
Date: Fri, 22 Feb 2013 08:38:44 -0800

> Smatch found a locking bug in netif_set_xps_queue in which we were not
> releasing the lock in the case of an allocation failure.
> 
> This change corrects that so that we release the xps_map_mutex before
> returning -ENOMEM in the case of an allocation failure.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>

Applied and queue up for -stable, thanks Alex.
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Alexander Duyck - Feb. 22, 2013, 9:21 p.m.
On 02/22/2013 12:14 PM, David Miller wrote:
> From: Alexander Duyck <alexander.h.duyck@intel.com>
> Date: Fri, 22 Feb 2013 08:38:44 -0800
>
>> Smatch found a locking bug in netif_set_xps_queue in which we were not
>> releasing the lock in the case of an allocation failure.
>>
>> This change corrects that so that we release the xps_map_mutex before
>> returning -ENOMEM in the case of an allocation failure.
>>
>> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Applied and queue up for -stable, thanks Alex.

No patch is needed for -stable.  This was something I had introduced
into net-next when I moved the XPS logic into its own function.

Thanks,

Alex
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David Miller - Feb. 22, 2013, 9:44 p.m.
From: Alexander Duyck <alexander.h.duyck@intel.com>
Date: Fri, 22 Feb 2013 13:21:09 -0800

> On 02/22/2013 12:14 PM, David Miller wrote:
>> From: Alexander Duyck <alexander.h.duyck@intel.com>
>> Date: Fri, 22 Feb 2013 08:38:44 -0800
>>
>>> Smatch found a locking bug in netif_set_xps_queue in which we were not
>>> releasing the lock in the case of an allocation failure.
>>>
>>> This change corrects that so that we release the xps_map_mutex before
>>> returning -ENOMEM in the case of an allocation failure.
>>>
>>> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
>> Applied and queue up for -stable, thanks Alex.
> 
> No patch is needed for -stable.  This was something I had introduced
> into net-next when I moved the XPS logic into its own function.

Great, thanks for letting me know.
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Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index 17bc535..18d8b5a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1882,8 +1882,10 @@  int netif_set_xps_queue(struct net_device *dev, struct cpumask *mask, u16 index)
 
 		if (!new_dev_maps)
 			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
-		if (!new_dev_maps)
+		if (!new_dev_maps) {
+			mutex_unlock(&xps_map_mutex);
 			return -ENOMEM;
+		}
 
 		map = dev_maps ? xmap_dereference(dev_maps->cpu_map[cpu]) :
 				 NULL;