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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 B2DF3C43381 for ; Thu, 21 Feb 2019 09:20:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CF55214AF for ; Thu, 21 Feb 2019 09:20:52 +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="kIAemxbp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727354AbfBUJUv (ORCPT ); Thu, 21 Feb 2019 04:20:51 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:33424 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725385AbfBUJUu (ORCPT ); Thu, 21 Feb 2019 04:20:50 -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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=wP//jFvsGdNSawgJBIo/KKWC9LGNeQdk4UowQ5cHBuU=; b=kIAemxbpBandbbJU8UFGKf9u+ d/uo+EwMEvmj+W34ozPy+phWNNrJVc84p1HF0OGxOdOKkyagqWLvFsGYgPRmSHV/+rLZBwLhOOmv/ bvwmJjJvwoUfRGfHgkkzdDhpSHM78/XtXa07fvbFxSHUeycyFwRP0fts4b8PLO/BCbmvLNCZkMZVb JngdLA98YrTBEVog6MG9sB9TDlkgjJgYX5LFuI3GhlAAxCiVr3JdVP3WygXdQak08WAiW37mdzW+l nHtiGBP12sf76jMMcf+xC2e0vSXqiXNxSx3mEWgfUFQ5V8kYDAGrQYEbadBkg1cMuK6Jx4KPrv3UG G5unB8urQ==; 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 1gwkWk-0007v3-ED; Thu, 21 Feb 2019 09:20:22 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CE4D82139CDFF; Thu, 21 Feb 2019 10:20:20 +0100 (CET) Date: Thu, 21 Feb 2019 10:20:20 +0100 From: Peter Zijlstra To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov , Christian Brauner , Daniel Borkmann , David Ahern , "David S. Miller" , Ido Schimmel , Ingo Molnar , "moderated list:INTEL ETHERNET DRIVERS" , Jakub Kicinski , Jeff Kirsher , Jesper Dangaard Brouer , John Fastabend , Josh Triplett , keescook@chromium.org, Lai Jiangshan , Martin KaFai Lau , Mathieu Desnoyers , netdev@vger.kernel.org, "Paul E. McKenney" , rcu@vger.kernel.org, Song Liu , Steven Rostedt , xdp-newbies@vger.kernel.org, Yonghong Song Subject: Re: [PATCH RFC 5/5] rcuwait: Replace rcu_assign_pointer() with WRITE_ONCE Message-ID: <20190221092020.GZ32477@hirez.programming.kicks-ass.net> References: <20190221054942.132388-1-joel@joelfernandes.org> <20190221054942.132388-6-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190221054942.132388-6-joel@joelfernandes.org> 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 Thu, Feb 21, 2019 at 12:49:42AM -0500, Joel Fernandes (Google) wrote: > This suppresses a sparse error generated due to the recently added > rcu_assign_pointer sparse check below. It seems WRITE_ONCE should be > sufficient here. > > >> kernel//locking/percpu-rwsem.c:162:9: sparse: error: incompatible > types in comparison expression (different address spaces) > > Signed-off-by: Joel Fernandes (Google) > --- > include/linux/rcuwait.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h > index 90bfa3279a01..9e5b4760e6c2 100644 > --- a/include/linux/rcuwait.h > +++ b/include/linux/rcuwait.h > @@ -44,7 +44,7 @@ extern void rcuwait_wake_up(struct rcuwait *w); > */ \ > WARN_ON(current->exit_state); \ > \ > - rcu_assign_pointer((w)->task, current); \ > + WRITE_ONCE((w)->task, current); \ > for (;;) { \ > /* \ > * Implicit barrier (A) pairs with (B) in \ Distinct lack of justification for loosing the RELEASE again.