[Libunwind-devel] Re: Call to strdup breaks heap profilers

[Arun Sharma]

On Tue, Jul 1, 2008 at 9:03 AM, Daniel Jacobowitz <address@hidden> wrote:

On Thu, Jun 26, 2008 at 11:55:42PM -0700, Arun Sharma wrote:
> On Thu, Jun 26, 2008 at 8:38 PM, Arun Sharma <address@hidden> wrote:
>
> > Hi Daniel,
> >
> > Looks like your patch from Feb introduced a call to strdup:
> >
> >
> > http://git.kernel.org/?p=libs/libunwind/libunwind.git;a=commit;h=3842dac7333e42aa44531eda34ba55200b99ccf8
> >
>
> It also introduced a few direct calls to malloc as well, which cause
> problems when libunwind is called from within malloc.

Hi Arun,

Sorry for breaking things.  Our mpatrol port, the original user of
this code, has a recursion guard; it was unavoidable, because mpatrol
instruments memcpy.  I'll try to fix it, but it will be a little
longer before I have time.

I've temporarily reverted this commit from our copy of libunwind - so it's not super urgent. But it'd be nice to get a fix in the longer term that doesn't involve calls to malloc.

Also, I'm curious about how the mpatrol recursion guard works. In our case, the lock in question is in the malloc implementation itself [1].

 -Arun

[1] http://goog-perftools.sourceforge.net/doc/tcmalloc.html