Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752068AbaLPXKy (ORCPT ); Tue, 16 Dec 2014 18:10:54 -0500 Received: from mail-ig0-f180.google.com ([209.85.213.180]:57435 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751721AbaLPXJz (ORCPT ); Tue, 16 Dec 2014 18:09:55 -0500 From: Dmitry Torokhov To: "Rafael J. Wysocki" , Viresh Kumar Cc: Thomas Petazzoni , Geert Uytterhoeven , Stefan Wahren , Paul Gortmaker , Nishanth Menon , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/4] PM / OPP: take RCU lock in dev_pm_opp_get_opp_count Date: Tue, 16 Dec 2014 15:09:38 -0800 Message-Id: <1418771379-24369-4-git-send-email-dtor@chromium.org> X-Mailer: git-send-email 2.2.0.rc0.207.ga3a616c In-Reply-To: <1418771379-24369-1-git-send-email-dtor@chromium.org> References: <1418771379-24369-1-git-send-email-dtor@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A lot of callers are missing the fact that dev_pm_opp_get_opp_count needs to be called under RCU lock. Given that RCU locks can safely be nested, instead of providing *_locked() API, let's take RCU lock inside dev_pm_opp_get_opp_count() and leave callers as is. Signed-off-by: Dmitry Torokhov --- drivers/base/power/opp.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c index 413c7fe..ee5eca2 100644 --- a/drivers/base/power/opp.c +++ b/drivers/base/power/opp.c @@ -216,9 +216,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq); * This function returns the number of available opps if there are any, * else returns 0 if none or the corresponding error value. * - * Locking: This function must be called under rcu_read_lock(). This function - * internally references two RCU protected structures: device_opp and opp which - * are safe as long as we are under a common RCU locked section. + * Locking: This function takes rcu_read_lock(). */ int dev_pm_opp_get_opp_count(struct device *dev) { @@ -226,13 +224,14 @@ int dev_pm_opp_get_opp_count(struct device *dev) struct dev_pm_opp *temp_opp; int count = 0; - opp_rcu_lockdep_assert(); + rcu_read_lock(); dev_opp = find_device_opp(dev); if (IS_ERR(dev_opp)) { - int r = PTR_ERR(dev_opp); - dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); - return r; + count = PTR_ERR(dev_opp); + dev_err(dev, "%s: device OPP not found (%d)\n", + __func__, count); + goto out_unlock; } list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { @@ -240,6 +239,8 @@ int dev_pm_opp_get_opp_count(struct device *dev) count++; } +out_unlock: + rcu_read_unlock(); return count; } EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count); -- 2.2.0.rc0.207.ga3a616c -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/