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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E53D2C433E1 for ; Wed, 20 May 2020 10:29:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C35E6207ED for ; Wed, 20 May 2020 10:29:04 +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="faG8a+VJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726697AbgETK3E (ORCPT ); Wed, 20 May 2020 06:29:04 -0400 Received: from merlin.infradead.org ([205.233.59.134]:52856 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726224AbgETK3D (ORCPT ); Wed, 20 May 2020 06:29:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=Pcnkdhzo7iybmY/3WHM6a4StwuJiDWWOYzMSkFwQnZk=; b=faG8a+VJtLLWswqGM9/4fhymDn ufqqw9OgQjgXYtTDE7nAqGEUdCbbE2Mt/fpp63fk46qu6qX+ljtb8wZ7wboqp/1JE6Q1rPogvGY7E aH+OHEZuBDWr0kx9FKcShW4Vdal8XB6MiwHbYBbwZSSOkSED9YHFeU/e8ovIYSim6E5QyJ6n1ICMI p52jeQShZ7j88YNZ4qqNCH0opOnYjNi5QkG/GSkh8Tupe7O2bax+HUl83cRkhQyjEGQvKlwawZFwR LZ6V1P4+spyRr73FS1hNVmp+QPPDGfrmUQOOTKLfjuTtJpy2VWT6Evp/B1+rON9sujijy0f9drG/r dI/lIRoQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbLtW-0005Q2-Jj; Wed, 20 May 2020 10:24:14 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id A4543300478; Wed, 20 May 2020 12:24:08 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 06F5325D60CB3; Wed, 20 May 2020 12:24:08 +0200 (CEST) Date: Wed, 20 May 2020 12:24:07 +0200 From: Peter Zijlstra To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Steven Rostedt , Will Deacon , Thomas Gleixner , "Paul E . McKenney" , Linus Torvalds , Lai Jiangshan , Josh Triplett , Mathieu Desnoyers , rcu@vger.kernel.org Subject: Re: [PATCH 3/8] srcu: Use local_lock() for per-CPU struct srcu_data access Message-ID: <20200520102407.GF317569@hirez.programming.kicks-ass.net> References: <20200519201912.1564477-1-bigeasy@linutronix.de> <20200519201912.1564477-4-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200519201912.1564477-4-bigeasy@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 19, 2020 at 10:19:07PM +0200, Sebastian Andrzej Siewior wrote: > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index 0c71505f0e19c..8d2b5f75145d7 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -25,6 +25,7 @@ > #include > #include > #include > +#include > > #include "rcu.h" > #include "rcu_segcblist.h" > @@ -735,6 +736,7 @@ static void srcu_flip(struct srcu_struct *ssp) > smp_mb(); /* D */ /* Pairs with C. */ > } > > +static DEFINE_LOCAL_LOCK(sda_lock); > /* > * If SRCU is likely idle, return true, otherwise return false. > * > @@ -765,13 +767,13 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp) > unsigned long tlast; > > /* If the local srcu_data structure has callbacks, not idle. */ > - local_irq_save(flags); > + local_lock_irqsave(sda_lock, flags); > sdp = this_cpu_ptr(ssp->sda); > if (rcu_segcblist_pend_cbs(&sdp->srcu_cblist)) { > - local_irq_restore(flags); > + local_unlock_irqrestore(sda_lock, flags); > return false; /* Callbacks already present, so not idle. */ > } > - local_irq_restore(flags); > + local_unlock_irqrestore(sda_lock, flags); Would it perhaps make sense to stick the local_lock in struct srcu_data ?