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Date: Wed, 07 Nov 2001 15:15:00 -0000
From: "H . J . Lu" <hjl@lucon.org>
To: Kevin Buettner <kevinb@cygnus.com>
Cc: gdb-patches@sources.redhat.com
Subject: Re: [PATCH RFA] lin-lwp.c: Block SIGCHLD events when attaching
Message-ID: <20011119113832.A8778@lucon.org>
References: <1011119193045.ZM16376@ocotillo.lan>
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In-Reply-To: <1011119193045.ZM16376@ocotillo.lan>; from kevinb@cygnus.com on Mon, Nov 19, 2001 at 12:30:45PM -0700
X-SW-Source: 2001-11/txt/msg00122.txt.bz2

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.


H.J.