From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH 12/12] PM / OPP: Update Documentation to remove RCU specific bits Date: Tue, 10 Jan 2017 10:09:41 +0530 Message-ID: <20170110043941.GE6332@vireshk-i7> References: <164ad6c0c6a5200eae99a7ac23554f33542f465b.1481106919.git.viresh.kumar@linaro.org> <20170109223937.GR17126@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pf0-f172.google.com ([209.85.192.172]:34403 "EHLO mail-pf0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764774AbdAJEjp (ORCPT ); Mon, 9 Jan 2017 23:39:45 -0500 Received: by mail-pf0-f172.google.com with SMTP id 127so39896975pfg.1 for ; Mon, 09 Jan 2017 20:39:44 -0800 (PST) Content-Disposition: inline In-Reply-To: <20170109223937.GR17126@codeaurora.org> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Stephen Boyd Cc: Rafael Wysocki , Viresh Kumar , Nishanth Menon , Len Brown , Pavel Machek , linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Guittot On 09-01-17, 14:39, Stephen Boyd wrote: > On 12/07, Viresh Kumar wrote: > > @@ -137,15 +121,18 @@ functions return the matching pointer representing the opp if a match is > > found, else returns error. These errors are expected to be handled by standard > > error checks such as IS_ERR() and appropriate actions taken by the caller. > > > > +Callers of these functions shall call dev_pm_opp_put() after they have used the > > +OPP. Otherwise the memory for the OPP will never get freed and result in > > +memleak. > > + > > dev_pm_opp_find_freq_exact - Search for an OPP based on an *exact* frequency and > > availability. This function is especially useful to enable an OPP which > > is not available by default. > > Example: In a case when SoC framework detects a situation where a > > higher frequency could be made available, it can use this function to > > find the OPP prior to call the dev_pm_opp_enable to actually make it available. > > - rcu_read_lock(); > > opp = dev_pm_opp_find_freq_exact(dev, 1000000000, false); > > - rcu_read_unlock(); > > + dev_pm_opp_put(opp); > > /* dont operate on the pointer.. just do a sanity check.. */ > > if (IS_ERR(opp)) { > > pr_err("frequency not disabled!\n"); > > @@ -163,9 +150,8 @@ dev_pm_opp_find_freq_floor - Search for an available OPP which is *at most* the > > frequency. > > Example: To find the highest opp for a device: > > freq = ULONG_MAX; > > - rcu_read_lock(); > > dev_pm_opp_find_freq_floor(dev, &freq); > > - rcu_read_unlock(); > > + dev_pm_opp_put(opp); > > opp doesn't exist in the scope here. Missing an assignment during > the dev_pm_opp_find_freq_floor() call? Thanks for noticing this. Following is the diff I am adding to this patch: diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt index be895e32022d..0c007e250cd1 100644 --- a/Documentation/power/opp.txt +++ b/Documentation/power/opp.txt @@ -150,7 +150,7 @@ dev_pm_opp_find_freq_floor - Search for an available OPP which is *at most* the frequency. Example: To find the highest opp for a device: freq = ULONG_MAX; - dev_pm_opp_find_freq_floor(dev, &freq); + opp = dev_pm_opp_find_freq_floor(dev, &freq); dev_pm_opp_put(opp); dev_pm_opp_find_freq_ceil - Search for an available OPP which is *at least* the @@ -159,7 +159,7 @@ dev_pm_opp_find_freq_ceil - Search for an available OPP which is *at least* the frequency. Example 1: To find the lowest opp for a device: freq = 0; - dev_pm_opp_find_freq_ceil(dev, &freq); + opp = dev_pm_opp_find_freq_ceil(dev, &freq); dev_pm_opp_put(opp); Example 2: A simplified implementation of a SoC cpufreq_driver->target: soc_cpufreq_target(..) @@ -252,6 +252,7 @@ dev_pm_opp_get_freq - Retrieve the freq represented by the opp pointer. if (!IS_ERR(max_opp) && !IS_ERR(requested_opp)) r = soc_test_validity(max_opp, requested_opp); dev_pm_opp_put(max_opp); + dev_pm_opp_put(requested_opp); /* do other things */ } soc_test_validity(..) Please add your RBY if it looks fine to you now. -- viresh