Messages in this thread | | | Date | Tue, 24 Jun 2003 12:25:51 +0200 | From | Pavel Machek <> | Subject | Re: Provide example copy_in_user implementation |
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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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