From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754908AbcFTTzy (ORCPT ); Mon, 20 Jun 2016 15:55:54 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:33107 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753939AbcFTTzv (ORCPT ); Mon, 20 Jun 2016 15:55:51 -0400 Date: Mon, 20 Jun 2016 15:55:44 -0400 From: Tejun Heo To: Petr Mladek Cc: Andrew Morton , Oleg Nesterov , Ingo Molnar , Peter Zijlstra , Steven Rostedt , "Paul E. McKenney" , Josh Triplett , Thomas Gleixner , Linus Torvalds , Jiri Kosina , Borislav Petkov , Michal Hocko , linux-mm@kvack.org, Vlastimil Babka , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 05/12] kthread: Add kthread_create_worker*() Message-ID: <20160620195544.GW3262@mtj.duckdns.org> References: <1466075851-24013-1-git-send-email-pmladek@suse.com> <1466075851-24013-6-git-send-email-pmladek@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466075851-24013-6-git-send-email-pmladek@suse.com> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 16, 2016 at 01:17:24PM +0200, Petr Mladek wrote: > Kthread workers are currently created using the classic kthread API, > namely kthread_run(). kthread_worker_fn() is passed as the @threadfn > parameter. > > This patch defines kthread_create_worker() and > kthread_create_worker_on_cpu() functions that hide implementation details. > > They enforce using kthread_worker_fn() for the main thread. But I doubt > that there are any plans to create any alternative. In fact, I think > that we do not want any alternative main thread because it would be > hard to support consistency with the rest of the kthread worker API. > > The naming and function of kthread_create_worker() is inspired by > the workqueues API like the rest of the kthread worker API. > > The kthread_create_worker_on_cpu() variant is motivated by the original > kthread_create_on_cpu(). Note that we need to bind per-CPU kthread > workers already when they are created. It makes the life easier. > kthread_bind() could not be used later for an already running worker. > > This patch does _not_ convert existing kthread workers. The kthread worker > API need more improvements first, e.g. a function to destroy the worker. > > IMPORTANT: > > kthread_create_worker_on_cpu() allows to use any format of the > worker name, in compare with kthread_create_on_cpu(). The good thing > is that it is more generic. The bad thing is that most users will > need to pass the cpu number in two parameters, e.g. > kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). > > To be honest, the main motivation was to avoid the need for an > empty va_list. The only legal way was to create a helper function that > would be called with an empty list. Other attempts caused compilation > warnings or even errors on different architectures. > > There were also other alternatives, for example, using #define or > splitting __kthread_create_worker(). The used solution looked > like the least ugly. > > Signed-off-by: Petr Mladek Acked-by: Tejun Heo Thanks. -- tejun