Re: [PATCH RFA] lin-lwp.c: Block SIGCHLD events when attaching

["H . J . Lu" <hjl at lucon dot org>]

On Mon, Nov 19, 2001 at 07:24:46PM -0700, Kevin Buettner wrote:
> On Nov 19,  5:42pm, Kevin Buettner wrote:
> 
> > > # gcc -g ex11.c -lpthread -lrt -D_GNU_SOURCE -static
> > > # a.out
> > > # gdb a.out
> > > ...
> > > (gdb) att 14226
> > > Attaching to program: /home/hjl/bugs/gdb/thread/a.out, process 14226
> > > ...
> > > lin-lwp.c:620: gdb-internal-error: stop_wait_callback: Assertion `pid == GET_LWP (lp->ptid)' failed.
> > > An internal GDB error was detected.  This may make further
> > > 
> > > ex11.c is from glibc and 14226 is the first thread. Your patch may fix
> > > it also.
> > 
> > I think this might be a different problem.  I haven't been able to
> > reproduce the exact problem that you mentioned above, either with
> > or without my patch.
> > 
> > I do occassionally see "Cannot find new threads: generic error".  I'm
> > going to try to figure this one out...
> 
> The "Cannot find new threads:  generic error" that I'm seeing in this
> program is happening because td_ta_thr_iter() in libthread_db.so is
> requesting that gdb read the memory associated with a struct
> _pthread_descr_struct (which has size 1056).  It turns out that gdb
> is able to read 1024 bytes of this struct, but no more.  (ptrace()
> returns EIO when attempting to read more.)
> 
> I'm not sure why this is happening.  Could it be that the manager thread
> is in the midst of updating the descriptor data structures?

Can you try gdb 5.1 to see what happens with ex11.c?



H.J.