Re: [PATCH 2/2] x86/asm/entry/32: Remove unnecessary optimization in stub32_clone

From: Josh Triplett
Date: Wed Apr 22 2015 - 16:12:58 EST


On Wed, Apr 22, 2015 at 11:22:02AM -0700, Linus Torvalds wrote:
> On Wed, Apr 22, 2015 at 10:10 AM, Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote:
> >
> > I do think my two-patch HAVE_COPY_THREAD_TLS series should go in fixing
> > this
>
> Ugh, I absolutely detesrt that patch.
>
> Don't make random crazy function signatures that depend on some config
> option. That's just evil. The patch is a mess of #ifdef's and should
> be shot in the head and staked with a silver stake to make sure it
> never re-appears.
>
> Either:
>
> (a) make the change for every architecture
>
> (b) have side-by-side interfaces. With different names!

...that's exactly what I did. They're called copy_thread and
copy_thread_tls; I very intentionally did not conditionally change the
signature of copy_thread, for exactly that reason. Those functions are
implemented in architecture-specific code, so the config option just
specifies which of the two functions the architecture provides.

*sys_clone* has different function signatures based on config options,
but I didn't touch that other than fixing the type of the tls argument.
That's historical baggage that we can't throw away without breaking
userspace.

- Josh Triplett
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