Re: [PATCH 3/4] Use devm_request_irq to avoid some checks

[Lars-Peter Clausen <lars@metafoo.de>]

On 10/19/2012 04:44 PM, Marcos Souza wrote:
> Hi Lars,
> 
> 2012/10/19 Lars-Peter Clausen <lars@metafoo.de>:
>> On 10/19/2012 01:41 AM, Marcos Paulo de Souza wrote:
>>> With this we can remove a lot of checks.
>>>
>>> Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
>>
>> This one is a bit more tricky and the driver currently gets it (partially
>> wrong). The issue is that since the power supply is referenced in the
>> interrupt handler, the IRQs should be requested after the power supply has
>> been registered and be freed before the power supply is unregistered.
>>
>> So devm can't really be used here. But as I said the current driver already
>> gets it wrong.
> 
> Tanks for all the reviews! I will resend these patches will your comments.
> 
> But in this case, there is a way that we can fix this issue about
> register/unregister IRQ?
> 
> Maybe another approach?
> 
> If you give some tips for me, my next patches will have this issue fixed too.
> 
> Thanks for all!
> 


To fix the potential race condition issue which the driver currently has, it is
necessary to request both IRQs only after the power supply has been registered.
This also means the power supply needs to be unregistered if requesting one of
the IRQs fails. Similar for the remove path the IRQs need to be freed before
the power supply is unregistered. And since the IRQs need to be freed before
the power supply is removed we can't use devm_request_irq.

- Lars

>>> ---
>>>  drivers/power/jz4740-battery.c |   25 ++++++++-----------------
>>>  1 file changed, 8 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/drivers/power/jz4740-battery.c b/drivers/power/jz4740-battery.c
>>> index 9d9b2a8..b80f7ed 100644
>>> --- a/drivers/power/jz4740-battery.c
>>> +++ b/drivers/power/jz4740-battery.c
>>> @@ -307,8 +307,8 @@ static int __devinit jz_battery_probe(struct platform_device *pdev)
>>>
>>>       INIT_DELAYED_WORK(&jz_battery->work, jz_battery_work);
>>>
>>> -     ret = request_irq(jz_battery->irq, jz_battery_irq_handler, 0, pdev->name,
>>> -                     jz_battery);
>>> +     ret = devm_request_irq(&pdev->dev, jz_battery->irq, jz_battery_irq_handler,
>>> +                             0, pdev->name, jz_battery);
>>>       if (ret) {
>>>               dev_err(&pdev->dev, "Failed to request irq %d\n", ret);
>>>               goto err;
>>> @@ -319,7 +319,7 @@ static int __devinit jz_battery_probe(struct platform_device *pdev)
>>>               ret = gpio_request(pdata->gpio_charge, dev_name(&pdev->dev));
>>>               if (ret) {
>>>                       dev_err(&pdev->dev, "charger state gpio request failed.\n");
>>> -                     goto err_free_irq;
>>> +                     goto err;
>>>               }
>>>               ret = gpio_direction_input(pdata->gpio_charge);
>>>               if (ret) {
>>> @@ -330,7 +330,8 @@ static int __devinit jz_battery_probe(struct platform_device *pdev)
>>>               jz_battery->charge_irq = gpio_to_irq(pdata->gpio_charge);
>>>
>>>               if (jz_battery->charge_irq >= 0) {
>>> -                     ret = request_irq(jz_battery->charge_irq,
>>> +                     ret = devm_request_irq(&pdev->dev,
>>> +                                 jz_battery->charge_irq,
>>>                                   jz_battery_charge_irq,
>>>                                   IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
>>>                                   dev_name(&pdev->dev), jz_battery);
>>> @@ -352,7 +353,7 @@ static int __devinit jz_battery_probe(struct platform_device *pdev)
>>>       ret = power_supply_register(&pdev->dev, &jz_battery->battery);
>>>       if (ret) {
>>>               dev_err(&pdev->dev, "power supply battery register failed.\n");
>>> -             goto err_free_charge_irq;
>>> +             goto err_free_gpio;
>>>       }
>>>
>>>       platform_set_drvdata(pdev, jz_battery);
>>> @@ -360,16 +361,11 @@ static int __devinit jz_battery_probe(struct platform_device *pdev)
>>>
>>>       return 0;
>>>
>>> -err_free_charge_irq:
>>> -     if (jz_battery->charge_irq >= 0)
>>> -             free_irq(jz_battery->charge_irq, jz_battery);
>>>  err_free_gpio:
>>>       if (gpio_is_valid(pdata->gpio_charge))
>>>               gpio_free(jz_battery->pdata->gpio_charge);
>>> -err_free_irq:
>>> -     free_irq(jz_battery->irq, jz_battery);
>>> -     platform_set_drvdata(pdev, NULL);
>>>  err:
>>> +     platform_set_drvdata(pdev, NULL);
>>>       return ret;
>>>  }
>>>
>>> @@ -379,16 +375,11 @@ static int __devexit jz_battery_remove(struct platform_device *pdev)
>>>
>>>       cancel_delayed_work_sync(&jz_battery->work);
>>>
>>> -     if (gpio_is_valid(jz_battery->pdata->gpio_charge)) {
>>> -             if (jz_battery->charge_irq >= 0)
>>> -                     free_irq(jz_battery->charge_irq, jz_battery);
>>> +     if (gpio_is_valid(jz_battery->pdata->gpio_charge))
>>>               gpio_free(jz_battery->pdata->gpio_charge);
>>> -     }
>>>
>>>       power_supply_unregister(&jz_battery->battery);
>>>
>>> -     free_irq(jz_battery->irq, jz_battery);
>>> -
>>>       return 0;
>>>  }
>>>
>>
> 
> 
>