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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1CACFC35242 for ; Sun, 26 Jan 2020 01:23:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBDA82075E for ; Sun, 26 Jan 2020 01:23:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580001835; bh=GT9CakDKgzHGUsSd9Pzep51RqWx2T4j5nL8jJpuNXfU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=MK04IzLk64ZDS9PfmTYxcgYLQ0Aubrv31qxc25k8bLg01D7SO25TvK43ZpeKP3wRN K6K8tIU+euCi9PsGJz9vau7vIjQyPOYrYZT1zTPUQeJY8dEfIxnG3SdlT/7swtT6iH LZ3HGoR//oJUEJQJhC/bhYz7XouS6fIdzCV/Qp2k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728884AbgAZBXz (ORCPT ); Sat, 25 Jan 2020 20:23:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:48778 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728792AbgAZBXz (ORCPT ); Sat, 25 Jan 2020 20:23:55 -0500 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D35DE2071E; Sun, 26 Jan 2020 01:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580001834; bh=GT9CakDKgzHGUsSd9Pzep51RqWx2T4j5nL8jJpuNXfU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=cHMhoBBGZV26DndY6i79l0/oheY4IbhYgCsuqfMECWp+RWh41bvab2aVqy5sh4VP2 zzY5c7ceHPkAgkzOeJIIw+jRuMUcrqF1H9vWDxzZF26XayhojEOK1n8F6qZrqmiqZb iWqsFYhbU643ZDKtlj+M0bfkHQQLNXzrJJ2KrkZc= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id A43853522863; Sat, 25 Jan 2020 17:23:54 -0800 (PST) Date: Sat, 25 Jan 2020 17:23:54 -0800 From: "Paul E. McKenney" To: Christian Brauner Cc: madhuparnabhowmik10@gmail.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, ebiederm@xmission.com, oleg@redhat.com, joel@joelfernandes.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, frextrite@gmail.com, rcu@vger.kernel.org Subject: Re: [PATCH] sched.h: Annotate sighand_struct with __rcu Message-ID: <20200126012354.GH2935@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200124045908.26389-1-madhuparnabhowmik10@gmail.com> <37A3FF92-0958-46DD-AFB1-CE72000B153F@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <37A3FF92-0958-46DD-AFB1-CE72000B153F@ubuntu.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Sat, Jan 25, 2020 at 10:41:06PM +0100, Christian Brauner wrote: > On January 24, 2020 5:59:08 AM GMT+01:00, madhuparnabhowmik10@gmail.com wrote: > >From: Madhuparna Bhowmik > > > >This patch fixes the following sparse errors by annotating the > >sighand_struct with __rcu > > > >kernel/fork.c:1511:9: error: incompatible types in comparison > >expression > >kernel/exit.c:100:19: error: incompatible types in comparison > >expression > >kernel/signal.c:1370:27: error: incompatible types in comparison > >expression > > > >This fix introduces the following sparse error in signal.c due to > >checking the sighand pointer without rcu primitives: > > > >kernel/signal.c:1386:21: error: incompatible types in comparison > >expression > > > >This new sparse error is also fixed in this patch. > > > >Signed-off-by: Madhuparna Bhowmik Acked-by: Paul E. McKenney > >--- > > include/linux/sched.h | 2 +- > > kernel/signal.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > >diff --git a/include/linux/sched.h b/include/linux/sched.h > >index b511e178a89f..7a351360ad54 100644 > >--- a/include/linux/sched.h > >+++ b/include/linux/sched.h > >@@ -918,7 +918,7 @@ struct task_struct { > > > > /* Signal handlers: */ > > struct signal_struct *signal; > >- struct sighand_struct *sighand; > >+ struct sighand_struct __rcu *sighand; > > sigset_t blocked; > > sigset_t real_blocked; > > /* Restored if set_restore_sigmask() was used: */ > >diff --git a/kernel/signal.c b/kernel/signal.c > >index bcd46f547db3..9ad8dea93dbb 100644 > >--- a/kernel/signal.c > >+++ b/kernel/signal.c > >@@ -1383,7 +1383,7 @@ struct sighand_struct *__lock_task_sighand(struct > >task_struct *tsk, > > * must see ->sighand == NULL. > > */ > > spin_lock_irqsave(&sighand->siglock, *flags); > >- if (likely(sighand == tsk->sighand)) > >+ if (likely(sighand == rcu_access_pointer(tsk->sighand))) > > break; > > spin_unlock_irqrestore(&sighand->siglock, *flags); > > } > > If Paul is happy with this and nobody wants to take it I'll pick this up. Works for me! Thanx, Paul