From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5588C4724C for ; Wed, 6 May 2020 15:37:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABDE220575 for ; Wed, 6 May 2020 15:37:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729486AbgEFPhB (ORCPT ); Wed, 6 May 2020 11:37:01 -0400 Received: from fieldses.org ([173.255.197.46]:47704 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725887AbgEFPg7 (ORCPT ); Wed, 6 May 2020 11:36:59 -0400 Received: by fieldses.org (Postfix, from userid 2815) id 918B71507; Wed, 6 May 2020 11:36:58 -0400 (EDT) Date: Wed, 6 May 2020 11:36:58 -0400 From: "J. Bruce Fields" To: Tejun Heo Cc: "J. Bruce Fields" , Linus Torvalds , "open list:NFS, SUNRPC, AND..." , Jeff Layton , David Howells , Shaohua Li , Oleg Nesterov , Linux Kernel Mailing List Subject: Re: [PATCH 0/4] allow multiple kthreadd's Message-ID: <20200506153658.GA21307@fieldses.org> References: <1588348912-24781-1-git-send-email-bfields@redhat.com> <20200501182154.GG5462@mtj.thefacebook.com> <20200505021514.GA43625@pick.fieldses.org> <20200505210118.GC27966@fieldses.org> <20200505210956.GA3350@mtj.thefacebook.com> <20200505212527.GA1265@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200505212527.GA1265@fieldses.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 05, 2020 at 05:25:27PM -0400, J. Bruce Fields wrote: > On Tue, May 05, 2020 at 05:09:56PM -0400, Tejun Heo wrote: > > It's not the end of the world but a bit hacky. I wonder whether something > > like the following would work better for identifying worker type so that you > > can do sth like > > > > if (kthread_fn(current) == nfsd) > > return kthread_data(current); > > else > > return NULL; > > Yes, definitely more generic, looks good to me. This is what I'm testing with. If it's OK with you, could I add your Signed-off-by and take it through the nfsd tree? I'll have some other patches that will depend on it. --b. commit 379bfe5257b6 Author: Tejun Heo Date: Tue May 5 21:26:07 2020 -0400 kthread: save thread function It's handy to keep the kthread_fn just as a unique cookie to identify classes of kthreads. E.g. if you can verify that a given task is running your thread_fn, then you may know what sort of type kthread_data points to. We'll use this in nfsd to pass some information into the vfs. Note it will need kthread_data() exported too. Signed-off-by: J. Bruce Fields diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 8bbcaad7ef0f..c00ee443833f 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -57,6 +57,7 @@ bool kthread_should_stop(void); bool kthread_should_park(void); bool __kthread_should_park(struct task_struct *k); bool kthread_freezable_should_stop(bool *was_frozen); +void *kthread_fn(struct task_struct *k); void *kthread_data(struct task_struct *k); void *kthread_probe_data(struct task_struct *k); int kthread_park(struct task_struct *k); diff --git a/kernel/kthread.c b/kernel/kthread.c index bfbfa481be3a..b87c4a9ba91d 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -46,6 +46,7 @@ struct kthread_create_info struct kthread { unsigned long flags; unsigned int cpu; + int (*threadfn)(void *); void *data; struct completion parked; struct completion exited; @@ -152,6 +153,20 @@ bool kthread_freezable_should_stop(bool *was_frozen) } EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); +/** + * kthread_fn - return the function specified on kthread creation + * @task: kthread task in question + * + * Returns NULL if the task is not a kthread. + */ +void *kthread_fn(struct task_struct *task) +{ + if (task->flags & PF_KTHREAD) + return to_kthread(task)->threadfn; + return NULL; +} +EXPORT_SYMBOL_GPL(kthread_fn); + /** * kthread_data - return data value specified on kthread creation * @task: kthread task in question @@ -164,6 +179,7 @@ void *kthread_data(struct task_struct *task) { return to_kthread(task)->data; } +EXPORT_SYMBOL_GPL(kthread_data); /** * kthread_probe_data - speculative version of kthread_data() @@ -244,6 +260,7 @@ static int kthread(void *_create) do_exit(-ENOMEM); } + self->threadfn = threadfn; self->data = data; init_completion(&self->exited); init_completion(&self->parked);