Re: rfkill rewrite bug

[Alan Jenkins <alan-jenkins@tuffmail.co.uk>]

Johannes Berg wrote:
> On Sat, 2009-04-18 at 10:43 +0100, Alan Jenkins wrote:
>
>   
>>>> When I looked at the code earlier, I saw no obvious replacement for 
>>>> rfkill_set_default().  So I tried disabling the wireless and rebooting 
>>>> to see what happened.  It didn't like that :-).
>>>>     
>>>>         
>>> Ok that wasn't too hard -- try this on top if you get a chance:
>>>   
>>>       
>> Great, that fixes the crash.
>>
>>
>> 1) I think we need to add a resume method to eeepc-laptop.
>>
>> Without this, funny things happen when I hibernate, disable wireless in
>> the BIOS, and resume:
>>
>>     ath5k phy0: failed to wake up the MAC chip
>>
>> It's an really stupid thing to do, but it can happen.  It's bad from a
>> UI point of view.  E.g. in network-manager, you can see a "wlan0"
>> device, but it doesn't work.
>>
>> The EEE rfkill is unusual in that it hotplugs the PCI device, making
>> eeepc-laptop something like a custom pci hotplug driver.  With your
>> rewrite, eeepc-laptop doesn't notice the state change on resume. 
>> Previously, the rfkill-core would restore the pre-hibernation state,
>> which would sort everything out.  I don't think anything else does this,
>> so we can just add a resume method to eeepc-laptop.  The resume method
>> would re-check the state and do the PCI hotplug dance if necessary.
>>
>> If you agree, I can do the patch for this and send it to you.
>>     
>
> Sounds good to me, yeah.
>
> I could make the rfkill core do that at resume, but I'm not really sure
> it's what we want -- there are too many cases imho:
>  * hard rfkill might have changed
>  * soft rfkill might still be ok in hw
>  * soft rfkill might need reconfiguring
> etc. I think generally it's saner to let the driver sort it out -- it
> can always ask for the current state by using set_hw_state() or so.
>
>   
>> 2) Do you have any thoughts about an rfkill_set_default() equivalent? 
>> AFAICS your current patch simply removes it.
>>
>> This means that when I boot linux, it doesn't respect the previous
>> rfkill state.  I can no longer disable the wireless in the BIOS setup
>> screen, and the rfkill state won't be preserved over reboots.
>>
>> I don't have a strong feeling about reboots _on their own_.  But I would
>> be annoyed if the option in the BIOS setup screen stopped working in a
>> future version of linux.  Admittedly it's only a matter of principle /
>> nostalgia - since the eeepc-laptop was fixed to implement rfkill
>> properly, I've never used the BIOS option in anger.
>>     
>
> That's odd, I thought I added a set_sw_state() to rfkill which would
> disable that rfkill. But there's rfkill_set_global_sw_state() which
> should do what you want -- can you try replacing the EEE set_sw_state
> call with that?
>
> johannes
>   

Well, I think the problem is clear :-P.

    if (!(rfkill_states_default_locked & BIT(rfkill->type))) {
        /* first of its kind */
        BUILD_BUG_ON(NUM_RFKILL_TYPES >
            sizeof(rfkill_states_default_locked) * 8);
        rfkill_states_default_locked |= BIT(rfkill->type);
        rfkill_global_states[rfkill->type].cur =
            rfkill_global_states[rfkill->type].def;
    }

One would expect to see a reference to rfkill->blocked in here.

Alan