Re: [Patch 1/4] Allow arch-specific cleanup before breakpoint unregistration

K.Prasad
2010-05-26T17:17:51Z

On Wed, May 26, 2010 at 10:54:41AM +0100, David Howells wrote:
> K.Prasad <prasad@linux.vnet.ibm.com> wrote:
>
> > > My understanding is weak function definitions must appear in a different C
> > > file than their call sites to work on some toolchains.
> > >
> >
> > Atleast, there are quite a few precedents inside the Linux kernel for
> > __weak functions being invoked from the file in which they are defined
> > (arch_hwblk_init, arch_enable_nonboot_cpus_begin and hw_perf_disable to
> > name a few).
> > Moreover the online GCC docs haven't any such constraints mentioned.
>
> I've seen problems in this area. gcc sometimes inlines a weak function that's
> in the same file as the call point.
>

We've seen such behaviour even otherwise....even with noinline attribute
in place. I'm not sure if this gcc fix
(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16922) helped correct the
behaviour, but the lesson has been to not trust a function to be
inlined/remain non-inline consistently.

> David

Thanks,
K.Prasad