[PATCH] cfg80211: Fix mutex locking in reg_last_request_cell_base

[PATCH] cfg80211: Fix mutex locking in reg_last_request_cell_base

[Mohammed Shafi Shajakhan]

From: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>

should fix the following issue

	[ 3229.815012] [ BUG: lock held when returning to user space! ]
	[ 3229.815016] 3.5.0-rc7-wl #28 Tainted: G        W  O
	[ 3229.815017]
	------------------------------------------------
	[ 3229.815019] wpa_supplicant/5783 is leaving the kernel with locks still held!
	[ 3229.815022] 1 lock held by wpa_supplicant/5783:
	[ 3229.815023]  #0: (reg_mutex){+.+.+.}, at: [<fa65834d>]
	reg_last_request_cell_base+0x1d/0x60 [cfg80211]

Cc: Luis Rodriguez <mcgrof@gmail.com>
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
---
 net/wireless/reg.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index dbb01df..2303ee7 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -929,11 +929,13 @@ static bool reg_request_cell_base(struct regulatory_request *request)
 
 bool reg_last_request_cell_base(void)
 {
+	bool val;
 	assert_cfg80211_lock();
 
 	mutex_lock(&reg_mutex);
-	return reg_request_cell_base(last_request);
+	val = reg_request_cell_base(last_request);
 	mutex_unlock(&reg_mutex);
+	return val;
 }
 
 #ifdef CONFIG_CFG80211_CERTIFICATION_ONUS
-- 
1.7.0.4

Re: [PATCH] cfg80211: Fix mutex locking in reg_last_request_cell_base

[Luciano Coelho]

On Wed, 2012-07-18 at 18:11 +0530, Mohammed Shafi Shajakhan wrote:
> From: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
> 
> should fix the following issue
> 
> 	[ 3229.815012] [ BUG: lock held when returning to user space! ]
> 	[ 3229.815016] 3.5.0-rc7-wl #28 Tainted: G        W  O
> 	[ 3229.815017]
> 	------------------------------------------------
> 	[ 3229.815019] wpa_supplicant/5783 is leaving the kernel with locks still held!
> 	[ 3229.815022] 1 lock held by wpa_supplicant/5783:
> 	[ 3229.815023]  #0: (reg_mutex){+.+.+.}, at: [<fa65834d>]
> 	reg_last_request_cell_base+0x1d/0x60 [cfg80211]
> 
> Cc: Luis Rodriguez <mcgrof@gmail.com>
> Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
> ---

Tested-by: Luciano Coelho <coelho@ti.com>

This actually also fixes a similar circular lock dependency bug when
starting AP mode with hostapd (which is the case I tested this patch
on): http://pastebin.com/AVczE1Ej

--
Luca.

Re: [PATCH] cfg80211: Fix mutex locking in reg_last_request_cell_base

[Mohammed Shafi]

Hi Luca,

On Wed, Jul 18, 2012 at 8:16 PM, Luciano Coelho <coelho@ti.com> wrote:
> On Wed, 2012-07-18 at 18:11 +0530, Mohammed Shafi Shajakhan wrote:
>> From: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
>>
>> should fix the following issue
>>
>>       [ 3229.815012] [ BUG: lock held when returning to user space! ]
>>       [ 3229.815016] 3.5.0-rc7-wl #28 Tainted: G        W  O
>>       [ 3229.815017]
>>       ------------------------------------------------
>>       [ 3229.815019] wpa_supplicant/5783 is leaving the kernel with locks still held!
>>       [ 3229.815022] 1 lock held by wpa_supplicant/5783:
>>       [ 3229.815023]  #0: (reg_mutex){+.+.+.}, at: [<fa65834d>]
>>       reg_last_request_cell_base+0x1d/0x60 [cfg80211]
>>
>> Cc: Luis Rodriguez <mcgrof@gmail.com>
>> Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
>> ---
>
> Tested-by: Luciano Coelho <coelho@ti.com>
>
> This actually also fixes a similar circular lock dependency bug when
> starting AP mode with hostapd (which is the case I tested this patch
> on): http://pastebin.com/AVczE1Ej

thanks !

>
> --
> Luca.
>
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-- 
thanks,
shafi

Re: [PATCH] cfg80211: Fix mutex locking in reg_last_request_cell_base

[Johannes Berg]

On Wed, 2012-07-18 at 18:11 +0530, Mohammed Shafi Shajakhan wrote:
> From: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
> 
> should fix the following issue
> 
> 	[ 3229.815012] [ BUG: lock held when returning to user space! ]
> 	[ 3229.815016] 3.5.0-rc7-wl #28 Tainted: G        W  O
> 	[ 3229.815017]
> 	------------------------------------------------
> 	[ 3229.815019] wpa_supplicant/5783 is leaving the kernel with locks still held!
> 	[ 3229.815022] 1 lock held by wpa_supplicant/5783:
> 	[ 3229.815023]  #0: (reg_mutex){+.+.+.}, at: [<fa65834d>]
> 	reg_last_request_cell_base+0x1d/0x60 [cfg80211]
> 
> Cc: Luis Rodriguez <mcgrof@gmail.com>
> Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>

Applied, thanks

johannes