From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-949627-1522616209-2-5497141888800708038 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no ("Email failed DMARC policy for domain") X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.249, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='uk', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-IgnoreVacation: yes ("Email failed DMARC policy for domain") X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1522616208; b=MLvJqVbs55JXhYcFXjhh0+OEPNydhJha9RCPn5Z+MtuMnGq5Yg PUtaAYOpsNfQET9lI8uHDNI2CcaSrhmYV/xzpzwSOfBJwSPYJNrScnwuAhvGkE5l OWd1DCJBoOvJSiIKmVavZ+VNplweBOp5kkQ3UWj2UPzqMMo5CTqGRte537aKCtiP G4NzpdnNQuBQ6DFE6RMutvc1UD2X8++MvWjh3rPru89fye/2V1HmMDxspNQzwHqn iSkH4lwMH+55CFODsYFvsY3Jb6sMANyLr9jgqzpWna/tbtyS1QObjA0/xRKHT9eP u3T3eC03YGSZm4D44vlcVV71dfHHGul+dMhA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=message-id:subject:from:to:cc:date :in-reply-to:references:content-type:mime-version :content-transfer-encoding:sender:list-id; s=fm2; t=1522616208; bh=Xjfv99vxSqjEcYpxiqHlUVJ4S8uz5LxAdtX5rFO5whc=; b=vrTK7BKl0nbw fzDgBrzbGl7OviIZMoiZ45+BdQmrdC24w2U64bcusVqY3elEmvyslgkeC5gJ8xvy f79LEU0Gd0rXkJ29LmDuDKoccsS92BbsKESVkm63/XqF6ohX80ysVlkq1tn8R+Ym IoQUkeUJnziAWsvZ/Xh6GLgE+gSvJrPro406ii34Hyg5tEC2+6DDRowNmReD4WnG 6N5TJN4mz47UqKmA9X+6ttA38DhPD2rOmPYvg/utwAo7qsk+HCHPp8/o4tbroazU 48kSx/tcVEfEnrQPxocCXdJ222ueAJK2Vvv9TO5B/6RrEt6rwQOPxeV7UdBEDt4w 18LPjgmgqw== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=codethink.co.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=codethink.co.uk header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=codethink.co.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=codethink.co.uk header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfOCmOLHDDz5fbFgfX3C9XnQJfV7NhbWaIblD1KP0HY59Xe3cZbc4T+6KjgufJ8YVnvQN+oQ6p0AplOlFwVFeBTMQRz6xzcknN6EqX8SWHXZ9Ecw6eVFT USd0wC+CRVzQu+t/ZDe1j+1WGGQft1nt07WP6lGmAeNZGOpH4AtvJPke+uSuO8xoBKKSoBMiKf0Lame162THdLdX75oVthzFxvbwlO68GcbqyEhB1i9fsds1 X-CM-Analysis: v=2.3 cv=WaUilXpX c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=IkcTkHD0fZMA:10 a=Kd1tUaAdevIA:10 a=QyXUC8HyAAAA:8 a=tZtAf7nzlrR6ftFY1vIA:9 a=QEXdDO2ut3YA:10 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751178AbeDAU4p (ORCPT ); Sun, 1 Apr 2018 16:56:45 -0400 Received: from imap1.codethink.co.uk ([176.9.8.82]:34403 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751028AbeDAU4p (ORCPT ); Sun, 1 Apr 2018 16:56:45 -0400 Message-ID: <1522616201.2654.79.camel@codethink.co.uk> Subject: Re: [PATCH 4.4 092/134] cpufreq: Fix governor module removal race From: Ben Hutchings To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, "Rafael J. Wysocki" , Viresh Kumar , Sasha Levin Date: Sun, 01 Apr 2018 21:56:41 +0100 In-Reply-To: <20180319171902.578082436@linuxfoundation.org> References: <20180319171849.024066323@linuxfoundation.org> <20180319171902.578082436@linuxfoundation.org> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, 2018-03-19 at 19:06 +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch.  If anyone has any objections, please let me know. > > ------------------ > > From: "Rafael J. Wysocki" > > > [ Upstream commit a8b149d32b663c1a4105273295184b78f53d33cf ] [...] > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -551,6 +551,8 @@ static int cpufreq_parse_governor(char * >   *governor = t; >   err = 0; >   } > + if (t && !try_module_get(t->owner)) > + t = NULL; This won't work because t is dead after this point.  The fix appears to depend on: commit 045149e6a22119e5bf0d16a0b24a4173a2abb71d Author: Rafael J. Wysocki Date: Thu Nov 23 01:23:16 2017 +0100 cpufreq: Clean up cpufreq_parse_governor() which moves the assignment to *governor further down. Ben.   >   mutex_unlock(&cpufreq_governor_mutex); >   } > @@ -669,6 +671,10 @@ static ssize_t store_scaling_governor(st >   return -EINVAL; >   >   ret = cpufreq_set_policy(policy, &new_policy); > + > + if (new_policy.governor) > + module_put(new_policy.governor->owner); > + >   return ret ? ret : count; >  } >   -- Ben Hutchings Software Developer, Codethink Ltd.