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, URIBL_BLOCKED,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 D7E15C35669 for ; Fri, 21 Feb 2020 20:25:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB78A2072C for ; Fri, 21 Feb 2020 20:25:39 +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="XymCjwuo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727912AbgBUUZi (ORCPT ); Fri, 21 Feb 2020 15:25:38 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:40262 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726483AbgBUUZi (ORCPT ); Fri, 21 Feb 2020 15:25:38 -0500 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=2Hcbu7VsxhWQs9BO+Aja19os7FBfjIizSEAD/jxIKN0=; b=XymCjwuobjJepMla2WyDSnMt82 wHklJoYIVwXJDYArgHkEAeiwB4P66pWfl36CylzFP2URQWLAV4B/ZdP4OAyWOpmXyOgQGsuPS6rmZ K6G7OPKgX9plbs8TCyW12z+dDj+avbXAQVwfJyKsFpqZxPmkTTnIHyJT8C4OgCWKmueBA9s6+Dfqr SC5giFO0TnAgTN7bA6cxnefE5kYnIbYOLEw5JMAnnMtYsa+nPr4L3tpt7RnuSEaOPlLj3g+7z5+Id 71lWOqBNaPM23qR3Ot1KJpr7ggBkoRZmbxgCm5lmu7bktPd/pb9s4ZqjttRh4wlrIPuNdGUnI02oz qKa7tWUA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j5ErK-0003Ys-C8; Fri, 21 Feb 2020 20:25:14 +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 9DEBC300478; Fri, 21 Feb 2020 21:23:18 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6B1F7209DB0F7; Fri, 21 Feb 2020 21:25:11 +0100 (CET) Date: Fri, 21 Feb 2020 21:25:11 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, luto@kernel.org, tony.luck@intel.com, frederic@kernel.org, dan.carpenter@oracle.com, mhiramat@kernel.org Subject: Re: [PATCH v4 01/27] lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions Message-ID: <20200221202511.GB14897@hirez.programming.kicks-ass.net> References: <20200221133416.777099322@infradead.org> <20200221134215.090538203@infradead.org> <20200221100855.2f9bec3a@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221100855.2f9bec3a@gandalf.local.home> 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 Fri, Feb 21, 2020 at 10:08:55AM -0500, Steven Rostedt wrote: > On Fri, 21 Feb 2020 14:34:17 +0100 > Peter Zijlstra wrote: > > > --- a/kernel/locking/lockdep.c > > +++ b/kernel/locking/lockdep.c > > @@ -379,13 +379,13 @@ void lockdep_init_task(struct task_struc > > > > void lockdep_off(void) > > { > > - current->lockdep_recursion++; > > + current->lockdep_recursion += BIT(16); > > } > > EXPORT_SYMBOL(lockdep_off); > > > > void lockdep_on(void) > > { > > - current->lockdep_recursion--; > > + current->lockdep_recursion -= BIT(16); > > } > > EXPORT_SYMBOL(lockdep_on); > > > > > + > > +static bool lockdep_nmi(void) > > +{ > > + if (current->lockdep_recursion & 0xFFFF) > > Nitpick, but the association with bit 16 and this mask really should be > defined as a macro somewhere and not have hard coded numbers. Right, I suppose I can do something like: #define LOCKDEP_RECURSION_BITS 16 #define LOCKDEP_OFF (1U << LOCKDEP_RECURSION_BITS) #define LOCKDEP_RECURSION_MASK (LOCKDEP_OFF - 1)