Re: linuxthreads 2.2.2 causes SEGV

[Marc Beuchat]

I just recompiled glibc-2.2.2 by putting back the pieces of code
which were removed (as indicated by Dan).  I can now compile
and run programs that use libpthread, BUT only if I statically
link with the threads library.  If I compile to use the dynamic
libpthread, I continue to get the SEGV in __pthread_alt_lock().

Marc

At 06:24 20-03-01 -0500, Dan Maas wrote:
> > Greetings all, I am homing in on the cause of this problem
> > (segfault inside __pthread_alt_lock() at startup time with
> > any program linked to libpthread.so).
>
> I have now found the exact change to glibc that triggered this.
> Long URL, watch the line break:
>
> http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/elf/soinit.c.diff?r1=1.8&r
> 2=1.9&cvsroot=glibc&f=h
>
> Ulrich Drepper added special support for initializing pthreads between glibc
> 2.0 and 2.1.94. But then he removed it for 2.2.2.
>
> Ulrich, could you explain why this was done? As of 2.2.2, glibc+pthreads is
> severely broken in certain configurations, since glibc's call to
> __register_frame_info tries to lock a pthreads mutex before pthreads has
> initialized the %gs register. Result: instant segfault on startup.
>
> Regards,
> Dan