Re: [PATCH] bug in setpgid()? process groups and thread groups

From: Jeremy Fitzhardinge (jeremy@goop.org)
Date: Sat Aug 02 2003 - 03:50:58 EST


On Sat, 2003-08-02 at 01:20, Ulrich Drepper wrote:
> Your approach with iterating over the threads is not acceptable (at
> least to me).

I've noticed that postings with patches get paid a lot more attention to
those without. It was just the patch I used to prove to myself what the
problem is.

> It is racy (concurrent runs are not synchronized)

Erm, it's protected by tasklist_lock, so that isn't a problem.

> 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.

I was considering that, but it needs changes all over the place where
people look at current->pgrp. This way makes for a clearer patch.

        J

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