Re: [PATCH V2 05/10] MIPS: lantiq: add watchdog support

[Sergei Shtylyov <sshtylyov@mvista.com>]

Hello.

Ralf Baechle wrote:

> > > +       switch (cmd) {
> > > +       case WDIOC_GETSUPPORT:
> > > +               ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
> > > +                               sizeof(ident)) ? -EFAULT : 0;
> >    Doesn't copy_to_user() return 0 or -EFAULT?
> No and that's a common cause of bugs.  copy_{from,to}_user returns the
> number of characters that could be be copied so the conversion to an
> error code is needed here.
   But then the code above would be wrong. Actually, it returns the number of 
bytes that could NOT be copied as I now see.
> The function takes a void argument and there is no benefit from casting
> to the full struct watchdog_info __user * pointer type other than maybe
> clarity to the human reader.
   Indeed.

>   Ralf
WBR, Sergei