Re: [RFC patch 08/18] cnt32_to_63 should use smp_rmb()

[Mathieu Desnoyers]

* Andrew Morton (akpm@xxxxxxxxxxxxxxxxxxxx) wrote:
> On Fri, 07 Nov 2008 17:10:00 +0000 David Howells <dhowells@xxxxxxxxxx> wrote:
> 
> > 
> > Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > 
> > > I'd expect it to behave in the same way as it would if the function was
> > > implemented out-of-line.
> > > 
> > > But it occurs to me that the modrobe-doesnt-work thing would happen if
> > > the function _is_ inlined anyway, so we won't be doing that.
> > > 
> > > Whatever.  Killing this many puppies because gcc may do something so
> > > bizarrely wrong isn't justifiable.
> > 
> > With gcc, you get one instance of the static variable from inside a static
> > (inline or outofline) function per .o file that invokes it, and these do not
> > merge even though they're common symbols.  I asked around and the opinion
> > seems to be that this is correct C.  I suppose it's the equivalent of cutting
> > and pasting a function between several files - why should the compiler assume
> > it's the same function in each?
> > 
> 
> OK, thanks, I guess that makes sense.  For static inline.  I wonder if
> `extern inline' or plain old `inline' should change it.
> 
> It's one of those things I hope I never need to know about, but perhaps
> we do somewhere have static storage in an inline.  Wouldn't surprise
> me, and I bet that if we do, it's a bug.

Tracepoints actually use that. It could be changed so they use :

DECLARE_TRACE() (in include/trace/group.h)
DEFINE_TRACE()  (in the appropriate kernel c file)
trace_somename(); (in the code)

instead. That would actually make more sense and remove the need for
multiple declarations when the same tracepoint name is used in many
spots (this is a problem kmemtrace has, it generates a lot of tracepoint
declarations).

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/