Re: [Outreachy kernel] [PATCH] staging: iio: Use devm functions

[Julia Lawall]

On Wed, 29 Mar 2017, Arushi Singhal wrote:

> Use managed resource functions devm_request_irq instead of request_irq.
> Remove corresponding calls to free_irq in the probe.

This transformation is dangerous, because it moves the stopping of
interrupts from where the free_irq is to after the end of the function (ie
in the caller).  You have to be very sure that the interrupt handler will
not use any resources that are freed by the subsequent cleanup code, ie
iio_trigger_unregister and iio_trigger_free.

julia


>
> Signed-off-by: Arushi Singhal <arushisinghal19971997@xxxxxxxxx>
> ---
>  drivers/staging/iio/trigger/iio-trig-bfin-timer.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/iio/trigger/iio-trig-bfin-timer.c b/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
> index 4e0b4eedb53d..42473d095911 100644
> --- a/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
> +++ b/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
> @@ -211,8 +211,9 @@ static int iio_bfin_tmr_trigger_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto out;
>
> -	ret = request_irq(st->irq, iio_bfin_tmr_trigger_isr,
> -			  0, st->trig->name, st);
> +	ret = devm_request_irq(&pdev->dev,
> +			       st->irq, iio_bfin_tmr_trigger_isr,
> +			       0, st->trig->name, st);
>  	if (ret) {
>  		dev_err(&pdev->dev,
>  			"request IRQ-%d failed", st->irq);
> @@ -256,7 +257,6 @@ static int iio_bfin_tmr_trigger_probe(struct platform_device *pdev)
>
>  	return 0;
>  out_free_irq:
> -	free_irq(st->irq, st);
>  out1:
>  	iio_trigger_unregister(st->trig);
>  out:
> @@ -271,7 +271,6 @@ static int iio_bfin_tmr_trigger_remove(struct platform_device *pdev)
>  	disable_gptimers(st->t->bit);
>  	if (st->output_enable)
>  		peripheral_free(st->t->pin);
> -	free_irq(st->irq, st);
>  	iio_trigger_unregister(st->trig);
>  	iio_trigger_free(st->trig);
>
> --
> 2.11.0
>
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