From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <archer-return-2053-listarch-archer=sourceware.org@sourceware.org>
Received: (qmail 382 invoked by alias); 19 Jul 2010 13:44:03 -0000
Mailing-List: contact archer-help@sourceware.org; run by ezmlm
Sender: <archer@sourceware.org>
Precedence: bulk
List-Post: <mailto:archer@sourceware.org>
List-Help: <mailto:archer-help@sourceware.org>
List-Subscribe: <mailto:archer-subscribe@sourceware.org>
List-Id: <archer.sourceware.org>
Received: (qmail 366 invoked by uid 22791); 19 Jul 2010 13:44:01 -0000
X-SWARE-Spam-Status: No, hits=-6.3 required=5.0
	tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD
X-Spam-Check-By: sourceware.org
Date: Mon, 19 Jul 2010 13:44:00 -0000
From: Oleg Nesterov <oleg@redhat.com>
To: archer@sourceware.org
Cc: Roland McGrath <roland@redhat.com>
Subject: BUG: add_thread_silent()->switch_to_thread(minus_one_ptid) is wrong
Message-ID: <20100719134135.GA13763@redhat.com>
References: <20100716205147.GA26313@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20100716205147.GA26313@redhat.com>
User-Agent: Mutt/1.5.18 (2008-05-17)
X-SW-Source: 2010-q3/txt/msg00036.txt.bz2

Hi.

I am trying to change ugdb.c to multiprocess mode, and now
I hit another bug in gdb.

	(gdb) target extended-remote /proc/ugdb
	(gdb) attach 980
	(gdb) info threads

results in

	thread.c:880: internal-error: switch_to_thread: Assertion `inf != NULL' failed.

Once again, I didn't see this problem in !multiprocess mode.

The immediate reason is clear, add_thread_silent() calls
switch_to_thread(minus_one_ptid), and find_inferior_pid(-1)
obviously fails. I guess add_thread_silent() is buggy and
should be fixed in any case.

But it is not clear to me what provokes this bug, gdb works
with gdbserver but not with /proc/ugdb.

Still investigaing...

Oleg.