Re: [PATCH] introduce kernel_execve function to replace __KERNEL_SYSCALLS__

From: Björn Steinbrink
Date: Tue Aug 22 2006 - 03:58:27 EST

On 2006.08.22 17:29:02 +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2006-08-21 at 17:12 +0200, Arnd Bergmann wrote:
> > On Monday 21 August 2006 02:36, Paul Mackerras wrote:
> > > > Iit turned out most of the architectures that already implement
> > > > their own execve() call instead of using the _syscall3 function
> > > > for it end up passing the return value of sys_execve down,
> > > > instead of setting errno.
> > >
> > > I really don't like having an "errno" variable in the kernel. What if
> > > two processes are doing an execve concurrently?
> >
> > The point is that we have two different schemes in the kernel that
> > conflict:
> >
> > alpha, arm{,26}, ia64, parisc, powerpc and x86_64 pass the error
> > code from execve, all others pass -1 and set the global errno.
> All other need to be fixed then... having an errno is just plain wrong.

I'm working on a patch loosely based on Arnd's that changes the
in-kernel syscall macros to directly return the error codes. Once
kernel_execve is implemented for each arch, only um should remain as a
user and I found only two calls there that care about the exact
non-zero return value, both are simple to adapt.
That should allow to get rid of errno completely. If someone knows a
reason why this is destined to fail (maybe syscalls returning char?!),
please let me know before I waste too much time on it ;)

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