Re: [PATCH] Export stack_used as __stack_used

[Florian Weimer <fweimer at redhat dot com>]

On 06/17/2016 09:50 PM, Gary Benson wrote:
> Florian Weimer wrote:
> > On 06/17/2016 01:37 PM, Gary Benson wrote:
> > > This commit renames "stack_used" as "__stack_used" and changes it
> > > from a static variable in allocatestack.c to an internally
> > > exported symbol available to all nptl source files.  This fixes
> > > bug 17629 (and thus GDB PR 9635).
> >
> > What do you mean by âexportâ?  The __ prefix suggests that you want
> > to export it as a symbol (probably GLIBC_PRIVATE), but I think you'd
> > need to update nptl/Versions in this case.
>
> No, I don't need that, it needs to be visible outside allocatestack.c
> but it doesn't need to be visible in, e.g., the output of "objdump -T".

Okay, then please declare it attribute_hidden.

> > If the variable remains nptl-internal, I expect that you could turn
> > it into a hidden symbol, and keep its current name.
>
> I may be wrong but I think its the rename that fixes the GDB bug.

Only if GDB explicitly searches for __stack_used (and that with the help 
of debugging information because it's not exported).

There isn't even a reference from libthread_db.

> If it's visible outside of allocatestack.c (i.e. it's not "static")
> then it should be named with a double-underscore, no?

Hmm, yes for the benefit of static linking and namespace cleanliness. 
So perhaps keep __stack_used, but make it hidden as well.  (I don't 
understand the nocommon business and what this addresses.)

Florian