linux-kernel - Re: [PATCH] extcon: arizona: Fix runtime PM imbalance on error

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Message-ID: <20200522165530.GH71940@ediswmail.ad.cirrus.com>
Date:   Fri, 22 May 2020 16:55:30 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Dinghao Liu <dinghao.liu@....edu.cn>
CC:     <kjlu@....edu>, MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        <patches@...nsource.cirrus.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] extcon: arizona: Fix runtime PM imbalance on error

On Fri, May 22, 2020 at 07:07:31PM +0800, Dinghao Liu wrote:
> When arizona_request_irq() returns an error code, a
> pairing runtime PM usage counter decrement is needed
> to keep the counter balanced. For error paths after
> this function, things are the same.
> 
> Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> ---

Good spot on the bug thank you.

>  drivers/extcon/extcon-arizona.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/extcon/extcon-arizona.c b/drivers/extcon/extcon-arizona.c
> index 7401733db08b..470bbc8e5089 100644
> --- a/drivers/extcon/extcon-arizona.c
> +++ b/drivers/extcon/extcon-arizona.c
> @@ -1744,6 +1744,7 @@ static int arizona_extcon_probe(struct platform_device *pdev)
>  err_rise:
>  	arizona_free_irq(arizona, jack_irq_rise, info);
>  err_gpio:
> +	pm_runtime_put(&pdev->dev);

However, I don't think this works as a fix. Firstly, the err_gpio
label is used before the call to pm_runtime_get_sync, this might
be ok since pm_runtime_enable hasn't been called yet but probably
better to add a new label for it.

Secondly, following the err_hpdet error path will also result in
a double put. In that case I don't think there is any reason why
we need to put before calling input_device_register so it might
just be simplest to move that put until after registering the
input device.

Thanks,
Charles

>  	gpiod_put(info->micd_pol_gpio);
>  err_register:
>  	pm_runtime_disable(&pdev->dev);
> -- 
> 2.17.1
>