Re: [PATCH] staging: comedi: cast to (unsigned int *)

Greg KH
2021-02-17T17:41:36Z

On Wed, Feb 17, 2021 at 10:29:08PM +0530, Atul Gopinathan wrote:
> Resolve the following warning generated by sparse:
>
> drivers/staging//comedi/comedi_fops.c:2956:23: warning: incorrect type in assignment (different address spaces)
> drivers/staging//comedi/comedi_fops.c:2956:23: expected unsigned int *chanlist
> drivers/staging//comedi/comedi_fops.c:2956:23: got void [noderef] <asn:1> *
>
> compat_ptr() has a return type of "void __user *"
> as defined in "include/linux/compat.h"
>
> cmd->chanlist is of type "unsigned int *" as defined
> in drivers/staging/comedi/comedi.h" in struct
> comedi_cmd.
>
> Signed-off-by: Atul Gopinathan <atulgopinathan@gmail.com>
> ---
> drivers/staging/comedi/comedi_fops.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
> index e85a99b68f31..fc4ec38012b4 100644
> --- a/drivers/staging/comedi/comedi_fops.c
> +++ b/drivers/staging/comedi/comedi_fops.c
> @@ -2953,7 +2953,7 @@ static int get_compat_cmd(struct comedi_cmd *cmd,
> cmd->scan_end_arg = v32.scan_end_arg;
> cmd->stop_src = v32.stop_src;
> cmd->stop_arg = v32.stop_arg;
> - cmd->chanlist = compat_ptr(v32.chanlist);
> + cmd->chanlist = (unsigned int __force *)compat_ptr(v32.chanlist);

__force? That feels wrong, something is odd if that is ever needed.

Are you _sure_ this is correct?

greg k-h