linux-kernel - Re: [PATCH] Staging: comedi: s626: Remove unnecessary cast on void pointer

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Message-ID: <20160121093851.GF6370@mwanda>
Date:	Thu, 21 Jan 2016 12:38:51 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Lucas Tanure <tanure@...ux.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ian Abbott <abbotti@....co.uk>, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Staging: comedi: s626: Remove unnecessary cast on void
 pointer

On Wed, Jan 20, 2016 at 09:48:39PM -0200, Lucas Tanure wrote:
> The conversion from void pointer to any other pointer type is guaranteed by
> the C programming language.
> 
> Signed-off-by: Lucas Tanure <tanure@...ux.com>
> ---
>  drivers/staging/comedi/drivers/s626.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
> index 35f0f67..13259f0 100644
> --- a/drivers/staging/comedi/drivers/s626.c
> +++ b/drivers/staging/comedi/drivers/s626.c
> @@ -1476,7 +1476,7 @@ static bool s626_handle_eos_interrupt(struct comedi_device *dev)
>  	 * first uint16_t in the buffer because it contains junk data
>  	 * from the final ADC of the previous poll list scan.
>  	 */
> -	uint32_t *readaddr = (uint32_t *)devpriv->ana_buf.logical_base + 1;
> +	uint32_t *readaddr = devpriv->ana_buf.logical_base + 1;


No.  This is a bug.  We need the cast for the pointer math to work.
The original code increments by sizeof(uint32_t) the new code by
sizeof(char).

regards,
dan carpenter