Re: Provide example copy_in_user implementation

[Pavel Machek <pavel@suse.cz>]

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.

If I wanted to optimize it, first step would be to copy over something
else than bytes. I'm afraid I do not want to optimize it.
								Pavel

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