On Tue, 21 May 2002, Andrew Morton wrote:
> Pavel makes a reasonable point that copy_*_user may elect
> to copy the data in something other than strictly ascending
> user virtual addresses. In which case it's not possible to return
> a sane "how much was copied" number.
I don't agree that that is true.
Do you have _any_ reasonable implementation taht would do that_
> And copy_*_user is buggy at present: it doesn't correctly handle
> the case where the source and destination of the copy are overlapping
> in the same physical page. Example code below.
So we have memcpy() semantics for read()/write(), big deal.
The same way you aren't supposed to use memcpy() for overlapping areas,
you're not supposed to read/write into such areas, for all the same
> One fix is to
> do the copy with descending addresses if src<dest or whatever.
No. That wouldn't work anyway, because the addresses are totally different
> But then how to return the number of bytes??
The way we do now, which is the CORRECT way.
Stop this idiocy.
The current interface is quite well-defined, and has good semantics. Every
single argument against it has been totally bogus, with no redeeming
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This archive was generated by hypermail 2b29 : Thu May 23 2002 - 22:00:23 EST