Re: copy_from_user() fixu

Richard Gooch (rgooch@atnf.csiro.au)
Wed, 26 Aug 1998 14:45:07 +1000

Chris Wedgwood writes:
> I think EFAULT is useful and acceptable behavior. Sure, it breaks the
> syscall/function call transparency arguments - but I don't see how
> having a higher degree of transparency is useful in practice (yes, in
> _theory_ it might feel better, but then you may as well write all
> your OS in scheme if thats all your interested in).

Agreed. It seems to me that the basis for removing EFAULT is
essentially an idealogical one. While you can argue that maybe some
future Linux implementation will implement read(3) on top of something
else (say readv(2) for example), I'd point out:

- probably read(3) wouldn't need to dereference the pointers anyway,
so faults will still occur in kernel space

- there is no significant practical benefit to changing the
implementation in any case

- you *will* break applications. That you may consider said
applications buggy is irrelevant: the question is whether it is
really worth breaking things.

Regards,

Richard....

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