From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755324AbbFBBsg (ORCPT ); Mon, 1 Jun 2015 21:48:36 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:57829 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754472AbbFBBsD (ORCPT ); Mon, 1 Jun 2015 21:48:03 -0400 From: Stephen Boyd To: linux-arm-msm@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Nishanth Menon , Viresh Kumar , Srinivas Kandagatla , Andy Gross , linux-pm@vger.kernel.org, Mark Brown , David Collins , Krzysztof Kozlowski Subject: [RFC/PATCH 4/6] OPP: Allow notifiers to call dev_pm_opp_get_{voltage,freq} RCU-free Date: Mon, 1 Jun 2015 18:47:57 -0700 Message-Id: <1433209679-31389-5-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 2.3.0.rc1.33.g42e4583 In-Reply-To: <1433209679-31389-1-git-send-email-sboyd@codeaurora.org> References: <1433209679-31389-1-git-send-email-sboyd@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We pass the dev_pm_opp structure to OPP notifiers but the users of the notifier need to surround calls to dev_pm_opp_get_*() with RCU read locks to avoid lockdep warnings. The notifier is already called with the dev_opp's srcu lock held, so it should be safe to assume the devm_pm_opp structure is already protected inside the notifier. Update the lockdep check for this. Cc: Krzysztof Kozlowski Signed-off-by: Stephen Boyd --- This is probably wrong, but it's what I had to hack up to be able to use the OPP functions from within the notifier to figure out the new values of the OPP without having to take an RCU read lock. drivers/base/power/opp.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c index b997a7eabcd4..6d75022c6a0e 100644 --- a/drivers/base/power/opp.c +++ b/drivers/base/power/opp.c @@ -108,9 +108,10 @@ static LIST_HEAD(dev_opp_list); /* Lock to allow exclusive modification to the device and opp lists */ static DEFINE_MUTEX(dev_opp_list_lock); -#define opp_rcu_lockdep_assert() \ +#define opp_rcu_lockdep_assert(s) \ do { \ rcu_lockdep_assert(rcu_read_lock_held() || \ + (s && srcu_read_lock_held(s)) || \ lockdep_is_held(&dev_opp_list_lock), \ "Missing rcu_read_lock() or " \ "dev_opp_list_lock protection"); \ @@ -169,9 +170,10 @@ unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp) struct dev_pm_opp *tmp_opp; unsigned long v = 0; - opp_rcu_lockdep_assert(); + opp_rcu_lockdep_assert(&opp->dev_opp->srcu_head.srcu); - tmp_opp = rcu_dereference(opp); + tmp_opp = srcu_dereference_check(opp, &opp->dev_opp->srcu_head.srcu, + rcu_read_lock_held()); if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) pr_err("%s: Invalid parameters\n", __func__); else @@ -201,9 +203,10 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp) struct dev_pm_opp *tmp_opp; unsigned long f = 0; - opp_rcu_lockdep_assert(); + opp_rcu_lockdep_assert(&opp->dev_opp->srcu_head.srcu); - tmp_opp = rcu_dereference(opp); + tmp_opp = srcu_dereference_check(opp, &opp->dev_opp->srcu_head.srcu, + rcu_read_lock_held()); if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) pr_err("%s: Invalid parameters\n", __func__); else @@ -282,7 +285,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev, struct device_opp *dev_opp; struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); - opp_rcu_lockdep_assert(); + opp_rcu_lockdep_assert(NULL); dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) { @@ -330,7 +333,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev, struct device_opp *dev_opp; struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); - opp_rcu_lockdep_assert(); + opp_rcu_lockdep_assert(NULL); if (!dev || !freq) { dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); @@ -380,7 +383,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, struct device_opp *dev_opp; struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); - opp_rcu_lockdep_assert(); + opp_rcu_lockdep_assert(NULL); if (!dev || !freq) { dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project