From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [PATCH] PM / OPP: Protect updates to list_dev with mutex Date: Fri, 30 Oct 2015 10:06:04 -0700 Message-ID: <20151030170604.GD19782@codeaurora.org> References: <5f8fac4ad84716ef68fc50ab0b78e11ad2837524.1446205160.git.viresh.kumar@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:60891 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750971AbbJ3RGH (ORCPT ); Fri, 30 Oct 2015 13:06:07 -0400 Content-Disposition: inline In-Reply-To: <5f8fac4ad84716ef68fc50ab0b78e11ad2837524.1446205160.git.viresh.kumar@linaro.org> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: Rafael Wysocki , mturquette@baylibre.com, linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, Bartlomiej Zolnierkiewicz , Dan Carpenter , Dmitry Torokhov , Greg Kroah-Hartman , Len Brown , open list , Nishanth Menon , Pavel Machek On 10/30, Viresh Kumar wrote: > dev_opp_list_lock is used everywhere to protect device and OPP lists, > but dev_pm_opp_set_sharing_cpus() is missed somehow. And instead we used > rcu-lock, which wouldn't help here as we are adding a new list_dev. > > This also fixes a problem where we have called kzalloc(..., GFP_KERNEL) > from within rcu-lock, which isn't allowed as kzalloc can sleep when > called with GFP_KERNEL. Care to share the splat here? > diff --git a/drivers/base/power/opp/cpu.c b/drivers/base/power/opp/cpu.c > index 7654c5606307..91f15b2e25ee 100644 > --- a/drivers/base/power/opp/cpu.c > +++ b/drivers/base/power/opp/cpu.c > @@ -124,12 +124,12 @@ int dev_pm_opp_set_sharing_cpus(struct device *cpu_dev, cpumask_var_t cpumask) > struct device *dev; > int cpu, ret = 0; > > - rcu_read_lock(); > + mutex_lock(&dev_opp_list_lock); > > dev_opp = _find_device_opp(cpu_dev); So does _find_device_opp() need to be called with rcu_read_lock() held or not? The comment above the function makes it sound like we need RCU, but we don't do that here anymore. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project