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

[Kevin Buettner <kevinb at cygnus dot com>]

On Nov 19, 11:38am, H . J . Lu wrote:

> On Mon, Nov 19, 2001 at 12:30:45PM -0700, Kevin Buettner wrote:
> > When doing a lin_lwp_attach_lwp(), it is sometimes possible to receive
> > a SIGCHLD signal thus causing the waitpid() call to fail with EINTR. 
> > This in turn causes the second assert() in lin_lwp_attach_lwp() to
> > fail.
> > 
> > Reproducing this problem can be somewhat difficult.  I've only been
> > able to reproduce it on a dual processor Linux/x86 machine.  I did
> > manage to reproduce it using the linux-dp program as follows:
> > 
> 
> Have you looked at
> 
> http://sources.redhat.com/ml/gdb/2001-09/msg00139.html
> 
> Specifically,
> 
> # 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...

Kevin