From patchwork Tue Jun 2 01:47:57 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Boyd X-Patchwork-Id: 6526271 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 3B9F19F326 for ; Tue, 2 Jun 2015 01:51:15 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 34C4C20384 for ; Tue, 2 Jun 2015 01:51:14 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 494F520380 for ; Tue, 2 Jun 2015 01:51:13 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YzbK6-000363-2F; Tue, 02 Jun 2015 01:48:58 +0000 Received: from smtp.codeaurora.org ([198.145.29.96]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YzbJW-0002u8-Fl for linux-arm-kernel@lists.infradead.org; Tue, 02 Jun 2015 01:48:24 +0000 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id DD97A140859; Tue, 2 Jun 2015 01:48:02 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id CDDEB140867; Tue, 2 Jun 2015 01:48:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from sboyd-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sboyd@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id C4BAA140859; Tue, 2 Jun 2015 01:48:01 +0000 (UTC) From: Stephen Boyd To: linux-arm-msm@vger.kernel.org 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> X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150601_184822_653132_D3CBEF36 X-CRM114-Status: GOOD ( 16.63 ) X-Spam-Score: -0.0 (/) Cc: Nishanth Menon , Krzysztof Kozlowski , David Collins , linux-pm@vger.kernel.org, Viresh Kumar , linux-kernel@vger.kernel.org, Mark Brown , Srinivas Kandagatla , Andy Gross , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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);