linux-kernel - RE: [PATCH 1/3] staging: comedi: amplc_dio200_common: prevent extra free

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Message-ID: <DC148C5AA1CEBA4E87973D432B1C2D8825F1E378@P3PWEX4MB008.ex4.secureserver.net>
Date:	Fri, 25 Jul 2014 18:23:10 +0000
From:	Hartley Sweeten <HartleyS@...ionengravers.com>
To:	Ian Abbott <abbotti@....co.uk>,
	"driverdev-devel@...uxdriverproject.org" 
	<driverdev-devel@...uxdriverproject.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/3] staging: comedi: amplc_dio200_common: prevent extra
 free_irq()

On Friday, July 25, 2014 10:07 AM, Ian Abbott wrote:
> `dio200_detach()` in "amplc_dio200.c" calls
> `amplc_dio200_common_detach()` in "amplc_dio200_common.c", followed by
> `comedi_legacy_detach()` in "../drivers.c".  Both of those functions
> call `free_irq()` if `dev->irq` is non-zero.  The second call produces a
> warning message because the handler has already been freed.  Prevent
> that by setting `dev->irq = 0` in `amplc_dio200_common_detach()`.
>
> Signed-off-by: Ian Abbott <abbotti@....co.uk>
> ---
>  drivers/staging/comedi/drivers/amplc_dio200_common.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/comedi/drivers/amplc_dio200_common.c b/drivers/staging/comedi/drivers/amplc_dio200_common.c
> index 78700e8..3592e58 100644
> --- a/drivers/staging/comedi/drivers/amplc_dio200_common.c
> +++ b/drivers/staging/comedi/drivers/amplc_dio200_common.c
> @@ -1202,8 +1202,10 @@ void amplc_dio200_common_detach(struct comedi_device *dev)
>  
>  	if (!thisboard || !devpriv)
>  		return;
> -	if (dev->irq)
> +	if (dev->irq) {
>  		free_irq(dev->irq, dev);
> +		dev->irq = 0;
> +	}
>  }
>  EXPORT_SYMBOL_GPL(amplc_dio200_common_detach);
 
Ian,

I have already gave a Reviewed-by signoff for this series.

After looking over the code I think a cleaner solution would be to:

1) Use comedi_legacy_detach() directly for the (*detach) in the
   legacy ISA driver.
2) Move the code from amplc_dio200_common_detach() into the
   (*detach) function for the PCI driver.
3) Remove the exported function amplc_dio200_common_detach().

Regards,
Hartley

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