From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753576Ab2A3XbD (ORCPT ); Mon, 30 Jan 2012 18:31:03 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:63934 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752832Ab2A3XbA (ORCPT ); Mon, 30 Jan 2012 18:31:00 -0500 Date: Mon, 30 Jan 2012 15:30:55 -0800 From: Tejun Heo To: "Srivatsa S. Bhat" Cc: rjw@sisk.pl, pavel@ucw.cz, len.brown@intel.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/4] PM/Freezer: Make thaw_processes() thaw only userspace tasks Message-ID: <20120130233055.GE27616@google.com> References: <20120130231342.11129.87187.stgit@srivatsabhat.in.ibm.com> <20120130231437.11129.3708.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120130231437.11129.3708.stgit@srivatsabhat.in.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 31, 2012 at 04:44:48AM +0530, Srivatsa S. Bhat wrote: > Currently the situation is: > > freeze_processes() - freezes only userspace tasks > freeze_kernel_threads() - freezes only kernel threads > thaw_kernel_threads() - thaws only kernel threads > thaw_processes() - thaws *everything* (both userspace tasks and kernel threads) Umm... I don't really get this. Why is this a problem? The list is not even correct. freeze_kernel_threads() doesn't freeze "only" kernel threads. It freezes all threads "including" kernel threads and that's only natural because you can't freeze kernel threads without freezing userland threads and of course you can't thaw userland threads without thawing kernel threads. The system simply won't work if you do it otherwise and making them disjoint operations increases the chance of bugs. These operations are naturally enclosed within each other and trying to break them apart isn't a good idea. What's the problem you're trying to solve here? I don't really see code clean up. Code is different but not necessarily cleaner and FWIW it seems more unnatural and brittle to me. Thanks. -- tejun