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SubjectRe: [PATCH 26/31] staging/comedi/das16: Make timer initialization unconditional
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On 01/09/17 00:29, Kees Cook wrote:
> With timer initialization made unconditional, there is no reason to
> make del_timer_sync() calls conditionally, there by removing the test
> of the .data field.
>
> Cc: Ian Abbott <abbotti@mev.co.uk>
> Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: devel@driverdev.osuosl.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/staging/comedi/drivers/das16.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/das16.c b/drivers/staging/comedi/drivers/das16.c
> index 5d157951f63f..4514179b2007 100644
> --- a/drivers/staging/comedi/drivers/das16.c
> +++ b/drivers/staging/comedi/drivers/das16.c
> @@ -941,10 +941,8 @@ static void das16_alloc_dma(struct comedi_device *dev, unsigned int dma_chan)
> /* DMA uses two buffers */
> devpriv->dma = comedi_isadma_alloc(dev, 2, dma_chan, dma_chan,
> DAS16_DMA_SIZE, COMEDI_ISADMA_READ);
> - if (devpriv->dma) {
> - setup_timer(&devpriv->timer, das16_timer_interrupt,
> - (unsigned long)dev);
> - }
> + setup_timer(&devpriv->timer, das16_timer_interrupt,
> + (unsigned long)dev);
> }

das16_alloc_dma() returns before the call to comedi_isadma_alloc() if
the dma_chan parameter is not one of the values 1 or 3, so setup_timer()
will not be called in that case.

>
> static void das16_free_dma(struct comedi_device *dev)
> @@ -952,8 +950,7 @@ static void das16_free_dma(struct comedi_device *dev)
> struct das16_private_struct *devpriv = dev->private;
>
> if (devpriv) {
> - if (devpriv->timer.data)
> - del_timer_sync(&devpriv->timer);
> + del_timer_sync(&devpriv->timer);

If setup_timer() has not been called (see remark above), this change
will break.

> comedi_isadma_free(devpriv->dma);
> }
> }
>


--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@mev.co.uk> )=-
-=( Web: http://www.mev.co.uk/ )=-

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