From: Ulrich Drepper <drepper@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Linux Kernel List <linux-kernel@vger.kernel.org>,
Roland McGrath <roland@redhat.com>, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] bug in setpgid()? process groups and thread groups
Date: Sat, 02 Aug 2003 01:20:05 -0700 [thread overview]
Message-ID: <3F2B7435.7070101@redhat.com> (raw)
In-Reply-To: <1059811048.18516.43.camel@ixodes.goop.org>
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Jeremy Fitzhardinge wrote:
> I think there's a bug in setpgid(). At present, it only allows the
> thread group leader to change process groups, but it doesn't change the
> other threads in the thread group to the new process group.
The PGID is not the only value which is handled incorrectly like this.
The PID, GID, etc all need to be treated similarly.
Your approach with iterating over the threads is not acceptable (at
least to me). It is racy (concurrent runs are not synchronized) and has
a non-constant time. We've sketched out already a mechanism which
solves to problem. Basically, most of the time the value from the
thread group leader is used (just follow the pointer). Then setting the
value is an atomic operation an constant.
The problem is that Linus already said it is too late for this for 2.6.
So we are waiting for a signal that the time is right. The changes
will be substantial since all the different IDs should be covered.
- --
- --------------. ,-. 444 Castro Street
Ulrich Drepper \ ,-----------------' \ Mountain View, CA 94041 USA
Red Hat `--' drepper at redhat.com `---------------------------
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next prev parent reply other threads:[~2003-08-02 8:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-02 7:57 [PATCH] bug in setpgid()? process groups and thread groups Jeremy Fitzhardinge
2003-08-02 8:20 ` Ulrich Drepper [this message]
2003-08-02 8:50 ` Jeremy Fitzhardinge
2003-08-02 19:08 ` Roland McGrath
2003-08-02 20:30 ` Nicholas Miell
2003-08-02 20:51 ` Alan Cox
2003-08-03 7:22 ` Florian Weimer
2003-08-03 21:00 ` Alan Cox
2003-08-03 4:15 ` Jeremy Fitzhardinge
2003-08-02 18:39 ` William Lee Irwin III
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