Subject: Re: [PATCH] drivers:net:wireless: Add proper locking for the function, b43_op_beacon_set_tim in main.c

From: nick <[email-masked]>
Date: Fri, 02 Jan 2015 12:13:33 -0500

Michael,
My fault I wasn't aware we were in atomic context, however if we are then why
not just remove the comment. If you want I can send in a patch explaining why
this comment is no longer needed.
Regards,
Nick

On 2015-01-02 04:27 AM, Michael Büsch wrote:
> On Fri,  2 Jan 2015 02:34:01 -0500
> Nicholas Krause <[email-masked]> wrote:
> 
>> This adds proper locking for the function, b43_op_beacon_set_tim in main.c by using the mutex lock
>> in the structure pointer wl, as embedded into this pointer as a mutex in order to protect against
>> multiple access to the pointer wl when updating the templates for this pointer in the function,
>> b43_update_templates internally in the function, b43_op_beacon_set_tim.
>>
>> Signed-off-by: Nicholas Krause <[email-masked]>
>> ---
>>  drivers/net/wireless/b43/main.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
>> index 47731cb..d568fc8 100644
>> --- a/drivers/net/wireless/b43/main.c
>> +++ b/drivers/net/wireless/b43/main.c
>> @@ -5094,8 +5094,9 @@ static int b43_op_beacon_set_tim(struct ieee80211_hw *hw,
>>  {
>>  	struct b43_wl *wl = hw_to_b43_wl(hw);
>>  
>> -	/* FIXME: add locking */
>> +	mutex_lock(&wl->mutex);
>>  	b43_update_templates(wl);
>> +	mutex_unlock(&wl->mutex);
>>  
>>  	return 0;
>>  }
> 
> Thanks for the patch.
> 
> However, this does not work. We are in atomic context here.
> Please see the b43-dev mailing list archives for a recent thread about that.
> I'm also pretty sure that this is safe without lock, due to the higher level locks in mac80211.
>