From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id mM5nB/4nGVv6egAAmS7hNA ; Thu, 07 Jun 2018 12:41:42 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id AA6E9608B8; Thu, 7 Jun 2018 12:41:42 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="D009vZ7n" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,T_DKIM_INVALID autolearn=unavailable autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 347FA607DC; Thu, 7 Jun 2018 12:41:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 347FA607DC Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932455AbeFGMlk (ORCPT + 25 others); Thu, 7 Jun 2018 08:41:40 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:58638 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932318AbeFGMli (ORCPT ); Thu, 7 Jun 2018 08:41:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=HivFva8XmiILUvOpfh8cyPRXxcOTRbiJ43X4emPP++w=; b=D009vZ7nNJBAkhzbS9JUc6yjv2 2vgdkyiEFWTS8sUbCDWd/ZK0VmlWlRdRC4NwV+FhoZWmWUbMMvGOhfLeLg7yAO18jdcQNJVfGvXmW Uv1COk9Jj6yQG0lhQsAd8RdjNVAithCRs7IR1ADppSv5K9Y+8uGl8fu55s8sAyFUougLg9Ns/Scqe J6biWP6DcvxlYl+34Hqyr2gnkhv98nDlDfZcqcSDWVwK/3YO6a+dbx2fYVpUbIDx8ZvMqcUv+sm34 THz+fyRQGxP0dIfP/DF7LTEBoXIRSVyroSoySP/U9A6XbIYfnqWAuYmhU3rftlPDxX/Gtcvq56L09 o3gj0QJw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fQuEI-0001Xb-Rx; Thu, 07 Jun 2018 12:41:29 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id A62E2201EA7AC; Thu, 7 Jun 2018 14:41:18 +0200 (CEST) Message-Id: <20180607124006.266038375@infradead.org> User-Agent: quilt/0.63-1 Date: Thu, 07 Jun 2018 14:33:14 +0200 From: Peter Zijlstra To: mingo@kernel.org, oleg@redhat.com, gkohli@codeaurora.org Cc: tglx@linutronix.de, mpe@ellerman.id.au, bigeasy@linutronix.de, linux-kernel@vger.kernel.org, will.deacon@arm.com, "Peter Zijlstra (Intel)" Subject: [PATCH 4/4] kthread: Simplify kthread_park() completion References: <20180607123310.866085998@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-kthread-3.patch Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now that smpboot_update_cpumask_percpu_thread() is gone, we no longer have anybody calling kthread_park() on already parked threads. So revert commit: b1f5b378e126 ("kthread: Allow kthread_park() on a parked kthread") Suggested-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) --- kernel/kthread.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -190,7 +190,7 @@ static void __kthread_parkme(struct kthr if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) break; - complete_all(&self->parked); + complete(&self->parked); schedule(); } __set_current_state(TASK_RUNNING); @@ -465,7 +465,6 @@ void kthread_unpark(struct task_struct * if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) __kthread_bind(k, kthread->cpu, TASK_PARKED); - reinit_completion(&kthread->parked); clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); /* * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. @@ -493,6 +492,9 @@ int kthread_park(struct task_struct *k) if (WARN_ON(k->flags & PF_EXITING)) return -ENOSYS; + if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) + return -EBUSY; + set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); if (k != current) { wake_up_process(k);