linux-kernel - Re: [PATCH] iio: magnetometer: ak8974: Fix the error handling of ak8974

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Date:   Sun, 10 Apr 2022 16:54:25 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Zheyu Ma <zheyuma97@...il.com>
Cc:     lars@...afoo.de, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] iio: magnetometer: ak8974: Fix the error handling of
 ak8974_probe()

On Sat,  9 Apr 2022 11:48:48 +0800
Zheyu Ma <zheyuma97@...il.com> wrote:

> When the driver fail at devm_regmap_init_i2c(), we will get the
> following splat:
> 
> [  106.797388] WARNING: CPU: 4 PID: 413 at drivers/regulator/core.c:2257 _regulator_put+0x3ec/0x4e0
> [  106.802183] RIP: 0010:_regulator_put+0x3ec/0x4e0
> [  106.811237] Call Trace:
> [  106.811515]  <TASK>
> [  106.811695]  regulator_bulk_free+0x82/0xe0
> [  106.812032]  devres_release_group+0x319/0x3d0
> [  106.812425]  i2c_device_probe+0x766/0x940
> 
> Fix this by disabling the regulators at the error path.
> 
> Signed-off-by: Zheyu Ma <zheyuma97@...il.com>
+ CC Linus W as it's his driver.

Fix looks correct to me, though the handling of runtime pm in here is
probably more complex than it needs to be (and hence this odd error
handling for this one place in the probe).

Jonathan

> ---
>  drivers/iio/magnetometer/ak8974.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/iio/magnetometer/ak8974.c b/drivers/iio/magnetometer/ak8974.c
> index e54feacfb980..84bbf7ccc887 100644
> --- a/drivers/iio/magnetometer/ak8974.c
> +++ b/drivers/iio/magnetometer/ak8974.c
> @@ -862,6 +862,7 @@ static int ak8974_probe(struct i2c_client *i2c,
>  		dev_err(&i2c->dev, "failed to allocate register map\n");
>  		pm_runtime_put_noidle(&i2c->dev);
>  		pm_runtime_disable(&i2c->dev);
> +		regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
>  		return PTR_ERR(ak8974->map);
>  	}
>