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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 021A5C3F2CD for ; Mon, 23 Mar 2020 16:31:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7EDE20719 for ; Mon, 23 Mar 2020 16:31:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Anw38VSd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727511AbgCWQbK (ORCPT ); Mon, 23 Mar 2020 12:31:10 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:35524 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727067AbgCWQbK (ORCPT ); Mon, 23 Mar 2020 12:31:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=omo/Na5ZROj4u9t7Bqw1Dw8ScS4aH9K7KDqXAWCXJOw=; b=Anw38VSd8Ip4H76yWLh85U4fU/ dYOPEDmJJniFncpwq7kP0/IdBpnZQ7ryQW1ENsMJ0TdH9fmSO/UFTHc/bFJts0aV5d/uZgKsEXFzb Ot+2T65qP9saMOjfypOXJ6/n0ler2+vxvkDymGg7dwq8Mub/fRzBzsUoPoEDib7zuv5frybBptAhI F8q/m1HTMhZn7brg3Ptat9RghQD9TWewhVKVOtGqYYauqtSqeeM/hHaWIx/EyS4kivpay96VBUJiH JzPoAnftvS9QZ8HekoORxE5Hpoq5/R4AGSrUVlGMihgAoWqX8zpyh5tKzgV6qTj+LonAq/XwxITCp M3z/w0tw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGPym-000288-U3; Mon, 23 Mar 2020 16:31:09 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 0E0FD983505; Mon, 23 Mar 2020 17:31:06 +0100 (CET) Date: Mon, 23 Mar 2020 17:31:05 +0100 From: Peter Zijlstra To: Frederic Weisbecker Cc: LKML , Sebastian Andrzej Siewior , "Paul E . McKenney" , Thomas Gleixner Subject: Re: [RFC PATCH 1/3] lockdep/irq: Be more strict about IRQ-threadable code end Message-ID: <20200323163105.GM2452@worktop.programming.kicks-ass.net> References: <20200323033207.32370-1-frederic@kernel.org> <20200323033207.32370-2-frederic@kernel.org> <20200323135320.GJ2452@worktop.programming.kicks-ass.net> <20200323153039.GA5755@lenoir> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200323153039.GA5755@lenoir> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 23, 2020 at 04:30:40PM +0100, Frederic Weisbecker wrote: > On Mon, Mar 23, 2020 at 02:53:20PM +0100, Peter Zijlstra wrote: > > On Mon, Mar 23, 2020 at 04:32:05AM +0100, Frederic Weisbecker wrote: > > > --- a/kernel/irq/handle.c > > > +++ b/kernel/irq/handle.c > > > @@ -144,18 +144,24 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags > > > > > > for_each_action_of_desc(desc, action) { > > > irqreturn_t res; > > > + bool threadable; > > > > > > /* > > > * If this IRQ would be threaded under force_irqthreads, mark it so. > > > */ > > > - if (irq_settings_can_thread(desc) && > > > - !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))) > > > + threadable = (irq_settings_can_thread(desc) && > > > + !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))); > > > + > > > + if (threadable) > > > trace_hardirq_threaded(); > > > > > > trace_irq_handler_entry(irq, action); > > > res = action->handler(irq, action->dev_id); > > > trace_irq_handler_exit(irq, action, res); > > > > > > + if (threadable) > > > + trace_hardirq_unthreaded(); > > > > AFAICT this doesn't work for nested IRQ handlers. > > So current->hardirq_threaded should be a counter perhaps? Yeah, see how the old code used the hardirq_context counter for exactly that. Also note how the old code was actually cheaper than this (minimally, but still).