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SubjectRe: Provide example copy_in_user implementation
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 (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html

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