Re: Provide example copy_in_user implementation

[Russell King]

On Tue, Jun 24, 2003 at 12:25:51PM +0200, Pavel Machek wrote:
> On Út 24-06-03 11:18:20, Russell King wrote:
> > On Tue, Jun 24, 2003 at 12:06:10PM +0200, Pavel Machek wrote:
> > > This patch adds example copy_in_user implementation (copy_in_user is
> > > needed for new ioctl32 implementation, all 64bit archs will need
> > > it)... Please apply,
> > 
> > get_user / put_user on byte quantities may be faster than using
> > copy_from_user/copy_to_user on byte quantities.  Yes, it may be
> > a generic implementation, but there's no point in purposely making
> > it inefficient.
> 
> Actually, it seems that most architectures do...
> 
> static inline unsigned long
> __copy_from_user(void *to, const void __user *from, unsigned long n)
> {
>         if (__builtin_constant_p(n)) {
>                 unsigned long ret;
> 
>                 switch (n) {
>                 case 1:
> 
> 
> ...so it should be exactly as fast. Ahha, not arm.

Note that ARM isn't 64 bit, I'm not worried about it.  Given that code
does get cut'n'pasted about the place, I still think its a good idea.
But its your code...

-- 
Russell King ([e-mail])                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html