Question regarding sparse warning in staging/lustre

[Greg Kroah-Hartman]

On Sun, Feb 08, 2015 at 10:27:23PM +0100, Adrian Remonda wrote:
> Hello,
> 
> I'm cleaning the drivers/staging/lustre driver.
> I have got the next warning from sparse:
> 
> drivers/staging/lustre/lnet/selftest//conctl.c:918:30: warning: incorrect type in argument 1 (different address spaces)
> drivers/staging/lustre/lnet/selftest//conctl.c:918:30:    expected void [noderef] <asn:1>*to
> drivers/staging/lustre/lnet/selftest//conctl.c:918:30:    got char *ioc_pbuf2
> 
> If I add the __user macro as next:
> 
> --- a/drivers/staging/lustre/lnet/selftest/conctl.c
> +++ b/drivers/staging/lustre/lnet/selftest/conctl.c
> @@ -46,7 +46,7 @@
>  #include "console.h"
>  
>  static int
> -lst_session_new_ioctl(lstio_session_new_args_t *args)
> +lst_session_new_ioctl(lstio_session_new_args_t __user *args)
>  {
>  	char      *name;
>  	int	rc;
>  	
> The warning turns to:
> 
> drivers/staging/lustre/lnet/selftest//conctl.c:825:13: warning: dereference of noderef expression
> 
> Now the question:
> Is this right or it is just a false warning from sparse? 
> Should the __user macro should be also inside the structure fields?

The user/kernel fields in lustre are a total mess, I wouldn't work on
them if you don't have to as they need an overhaul in some areas.

So I'd recommend just staying away :)

good luck!

greg k-h