Re: [PATCH] make ds1wm driver to check ds1wm_platform_data pointer against NULL

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 9 Nov 2007 14:07:31 +0800
"eric miao" <eric.y.miao@gmail.com> wrote:

> Do a sanity check for the "struct ds1wm_platform_data" pointer passed in
> by the platform_device, and so to enforce each platform to provide a
> valid structure.
> 
> Signed-off-by: eric miao <eric.miao@marvell.com>
> ---
>  drivers/w1/masters/ds1wm.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c
> index 5747997..11ce9ec 100644
> --- a/drivers/w1/masters/ds1wm.c
> +++ b/drivers/w1/masters/ds1wm.c
> @@ -351,6 +351,10 @@ static int ds1wm_probe(struct platform_device *pdev)
>  		goto err0;
>  	}
>  	plat = pdev->dev.platform_data;
> +	if (!plat) {
> +		ret = -ENXIO;
> +		goto err0;
> +	}
>  	ds1wm_data->bus_shift = plat->bus_shift;
>  	ds1wm_data->pdev = pdev;
>  	ds1wm_data->pdata = plat;

I don't understand this change.  Could you please provide some more details
regarding what problem it is solving?  How can pdev->dev.platform_data==NULL
come about?

Thanks.