Firefox crash during dtrace attach under -CURRENT

[symbolics at gmx.com]

On Fri, Oct 25, 2013 at 11:47:06AM +0100, symbolics at gmx.com wrote:
> On Wed, Oct 23, 2013 at 10:59:02PM -0400, Mark Johnston wrote:
> > On Wed, Oct 23, 2013 at 09:30:09PM +0100, symbolics at gmx.com wrote:
> > > Hi,
> > > 
> > > http://dtrace.org/blogs/brendan/2011/02/11/dtrace-pid-provider-arguments/
> > > 
> > > I tried to follow some of the examples but I crash the Firefox process
> > > each time. Sometimes DTrace manages to collect a little data before the
> > > death.
> > > 
> > > [...]
> > > 
> > > Is this a known problem or should I send a PR?
> > 
> > Thanks for reporting this: I was able to reproduce the crash and managed
> > to find a nasty pair of bugs. Could you test the patch below and let me
> > know if it fixes the problem for you as well? If you see more crashes,
> > please include the backtrace and signo from gdb again; it would likely
> > be a different problem that needs to be debugged and fixed separately.
> 
> Hi Mark,
> 
> This helps but there still may be some issues. First time I used this
> I found that when I killed the DTrace process Firefox went down too
> with a SIGTRAP. I have a possibly unhelpful core from this:
> 

Another data point. I attached to mutt and reviewed some of the calls it
was making. Subsequently I killed DTrace, went to to look at other
things and a while later when back to check my mail. On attempting to
change into a different mail folder mutt died with a SIGTRAP. It seems
like DTrace isn't tidying up after itself?

(gdb) bt
#0  0x0000000800722541 in r_debug_state (rd=0x802425480, m=0x7fffffff6c28)
    at /usr/home/dm/git/freebsd/libexec/rtld-elf/rtld.c:3491
#1  0x0000000000000000 in ?? ()

--sym