linux-kernel - Re: [PATCH] pinctrl: qcom: Release pin ranges when gpiochip_irqchip

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Date:	Fri, 29 Aug 2014 12:49:27 +0530
From:	Pramod Gurav <pramod.gurav@...rtplayin.com>
To:	Bjorn Andersson <bjorn.andersson@...ymobile.com>
CC:	Bjorn Andersson <bjorn@...o.se>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	"Ivan T. Ivanov" <iivanov@...sol.com>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] pinctrl: qcom: Release pin ranges when gpiochip_irqchip_add
 fails



On 29-08-2014 09:19 AM, Bjorn Andersson wrote:
> On Thu 28 Aug 00:13 PDT 2014, Pramod Gurav wrote:
> 
>> On Thursday 28 August 2014 02:54 AM, Bjorn Andersson wrote:
>>> On Wed, Aug 27, 2014 at 3:57 AM, Pramod Gurav
>>> <pramod.gurav@...rtplayin.com> wrote:
>>>> This patches adds a call to gpiochip_remove_pin_ranges when
>>>> gpiochip_irqchip_add fails to release memory allocated for pin_ranges.
>>>>
>>>> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
>>>> @@ -845,6 +845,7 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
>>>>                                    IRQ_TYPE_NONE);
>>>>         if (ret) {
>>>>                 dev_err(pctrl->dev, "Failed to add irqchip to gpiochip\n");
>>>> +               gpiochip_remove_pin_ranges(chip);
>>>>                 return -ENOSYS;
>>>>         }
>>>
>>> Good catch, I guess this was lost in the introduction of gpiochip_irqchip...
>>>
>>>
>>> Rather than just releasing the pin_ranges of the gpio_chip you should
>>> probably add a gpiochip_remove() both here and in the case of
>>> gpiochip_add_pin_range() failing.
>>
>> Thanks for review. But if I see implementation of gpiochip_remove() it does:
>> 	gpiochip_irqchip_remove(chip);
>>         gpiochip_remove_pin_ranges(chip);
>>         of_gpiochip_remove(chip);
>>
>> In above failure case only gpiochip_add() and gpiochip_add_pin_range()
>> have been successful hence I thought that would cause any problem to add
>> gpiochip_remove(). If that is not a problem I think we can call
>> gpiochip_remove() in fail case of gpiochip_add_pin_range() as well.
>> Do I make sense?
>>
> 
> As soon as gpiochip_add() have returned successfully we will have a live
> gpio_chip, upon returning unsuccessfully from probe devres will free the pctrl
> node and the gpio core will continue to operate on freed memory.
> 
> Therefor we need to call gpio_remove() in the ccase of both
> gpiochip_add_pin_range() and gpiochip_irqchip_add() failing.
> 
> The gpio_remove() does as you say remove those additional items, but handles
> the case where they are not yet "allocated".
> 
> I hope this answers your conserns.
That really does. Thanks for your time. Will resend the patch with
handling failure cases of both gpiochip_add_pin_range() and
gpiochip_irqchip_add().
> 
> Regards,
> Bjorn
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