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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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