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=-7.1 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 autolearn=unavailable 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 A95CDC3F2CD for ; Sun, 1 Mar 2020 20:13:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FF0E246BF for ; Sun, 1 Mar 2020 20:13:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583093587; bh=KWncVSYwypNktqfGtIDhf9jfBw9MNLKepJm5DsnYDug=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=CpcL4AgWN4Ebk85YH1rMbdv9UiSjND4aM/+2WeL4iZxQ8m5tOADkjOCFLYqHjf3Dt 9DKyUXJXgwpk2xSKADaFH1BkDIKJ4o+tQv89mD/3Lo/JVQoGDKcJ7GGnvjvwAvqevo JG2+PrXDnzJq5B5xof21exc0hMOuJjopJqNbz8K0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726561AbgCAUNG (ORCPT ); Sun, 1 Mar 2020 15:13:06 -0500 Received: from mail-oi1-f194.google.com ([209.85.167.194]:36937 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726050AbgCAUNG (ORCPT ); Sun, 1 Mar 2020 15:13:06 -0500 Received: by mail-oi1-f194.google.com with SMTP id 5so2697774oiy.4; Sun, 01 Mar 2020 12:13:04 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EFSBXCeJ1jB8KcQMkp6NN1TRtUlXUbslxnRcWQMIR6I=; b=he73iD3UgVGkFxGZI4jh1kZswVamv7f8BTzZWf6eR5iF5ZeVryLEv2aO4JbY+XxXRD Gyp5kV+Z2y9k5J3njjuj8MwG4T6lWegl5/Z6ChA2gzzd6vuBp5sCo+vs742QGioyjogj VOaGWryoS+4bj11YQgBOb1EnPUmcFLJQuPyOuyMLd3Dz8SUCOSPSKruJW+BeJQIbjtVo DEFld/Mt9ylGQpVVWj8IYZk8hvyCO3sncioLddSbVTg5Budz7Qo9TPP1HhG1AdKmzhEZ 1Ak0MxbmjAP+/mWR8t9Ls3DdmOyMLLS+3JXgCTD3P3G2jz/cun8idJQOuPUUEBx3Hv61 Ku2A== X-Gm-Message-State: APjAAAXSj4NJ4oqBkR877QzqEis5Mki9oBkSKsCIswnYc2RJFGoUpBbc ezT3aZoVhJKJJUjQLjdWq31zbffZs0QZxY7Mt88= X-Google-Smtp-Source: APXvYqxbxPHmtfRGPpPP1hveHtyD20S1Jgyu5yQkA7cDSv5uULtoifR1CJMcxL/u/2XdY7RWZkl38PW9OoOvYdgqVlM= X-Received: by 2002:aca:c044:: with SMTP id q65mr4390997oif.68.1583093583908; Sun, 01 Mar 2020 12:13:03 -0800 (PST) MIME-Version: 1.0 References: <20200228174630.8989-1-madhuparnabhowmik10@gmail.com> In-Reply-To: <20200228174630.8989-1-madhuparnabhowmik10@gmail.com> From: "Rafael J. Wysocki" Date: Sun, 1 Mar 2020 21:12:53 +0100 Message-ID: Subject: Re: [PATCH 1/2] drivers: base: power: main: Use built-in RCU list checking To: madhuparnabhowmik10@gmail.com, Joel Fernandes Cc: "Rafael J. Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , Linux PM , Linux Kernel Mailing List , frextrite@gmail.com, linux-kernel-mentees@lists.linuxfoundation.org, paulmck@kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 28, 2020 at 6:47 PM wrote: > > From: Madhuparna Bhowmik > > This patch passes the cond argument to list_for_each_entry_rcu() > to fix the following false-positive lockdep warnings: > > [ 330.302784] ============================= > [ 330.302789] WARNING: suspicious RCU usage > [ 330.302796] 5.6.0-rc1+ #5 Not tainted > [ 330.302801] ----------------------------- > [ 330.302808] drivers/base/power/main.c:326 RCU-list traversed in non-reader section!! > > [ 330.303303] ============================= > [ 330.303307] WARNING: suspicious RCU usage > [ 330.303311] 5.6.0-rc1+ #5 Not tainted > [ 330.303315] ----------------------------- > [ 330.303319] drivers/base/power/main.c:1698 RCU-list traversed in non-reader section!! > > [ 331.934969] ============================= > [ 331.934971] WARNING: suspicious RCU usage > [ 331.934973] 5.6.0-rc1+ #5 Not tainted > [ 331.934975] ----------------------------- > [ 331.934977] drivers/base/power/main.c:1238 RCU-list traversed in non-reader section!! > > [ 332.467772] WARNING: suspicious RCU usage > [ 332.467775] 5.6.0-rc1+ #5 Not tainted > [ 332.467775] ----------------------------- > [ 332.467778] drivers/base/power/main.c:269 RCU-list traversed in non-reader section!! I don't see these warnings in the kernels run locally here. What do you do to get them? Joel, any comments here? > > Signed-off-by: Madhuparna Bhowmik > --- > drivers/base/power/main.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index 0e99a760aebd..742c05f3c1e7 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -266,7 +266,8 @@ static void dpm_wait_for_suppliers(struct device *dev, bool async) > * callbacks freeing the link objects for the links in the list we're > * walking. > */ > - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) > + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node, > + device_links_read_lock_held()) > if (READ_ONCE(link->status) != DL_STATE_DORMANT) > dpm_wait(link->supplier, async); > > @@ -323,7 +324,8 @@ static void dpm_wait_for_consumers(struct device *dev, bool async) > * continue instead of trying to continue in parallel with its > * unregistration). > */ > - list_for_each_entry_rcu(link, &dev->links.consumers, s_node) > + list_for_each_entry_rcu(link, &dev->links.consumers, s_node, > + device_links_read_lock_held()) > if (READ_ONCE(link->status) != DL_STATE_DORMANT) > dpm_wait(link->consumer, async); > > @@ -1235,7 +1237,8 @@ static void dpm_superior_set_must_resume(struct device *dev) > > idx = device_links_read_lock(); > > - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) > + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node, > + device_links_read_lock_held()) > link->supplier->power.must_resume = true; > > device_links_read_unlock(idx); > @@ -1695,7 +1698,8 @@ static void dpm_clear_superiors_direct_complete(struct device *dev) > > idx = device_links_read_lock(); > > - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) { > + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node, > + device_links_read_lock_held()) { > spin_lock_irq(&link->supplier->power.lock); > link->supplier->power.direct_complete = false; > spin_unlock_irq(&link->supplier->power.lock); > -- > 2.17.1 >