From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752802Ab0INHq7 (ORCPT ); Tue, 14 Sep 2010 03:46:59 -0400 Received: from mga02.intel.com ([134.134.136.20]:61060 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751965Ab0INHq6 (ORCPT ); Tue, 14 Sep 2010 03:46:58 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.56,363,1280732400"; d="scan'208";a="657060295" Message-ID: <4C8F2863.5070003@linux.intel.com> Date: Tue, 14 Sep 2010 15:46:43 +0800 From: Chen Gong User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.9) Gecko/20100825 Thunderbird/3.1.3 MIME-Version: 1.0 To: Jan Beulich CC: fenghua.yu@intel.com, linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org Subject: Re: [lm-sensors] [PATCH] x86/hwmon: fix module init for hotplug-but-no-device-found case References: <4C8E139F0200007800015AA5@vpn.id2.novell.com> <4C8F167E.40506@linux.intel.com> <4C8F36B40200007800015E6B@vpn.id2.novell.com> In-Reply-To: <4C8F36B40200007800015E6B@vpn.id2.novell.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 9/14/2010 2:47 PM, Jan Beulich 写道: >>>> On 14.09.10 at 08:30, Chen Gong wrote: >> 于 9/13/2010 6:05 PM, Jan Beulich 写道: >>> In commit 0dca94baeab4a1a514841b0a4c8e3a51dfb4d5ae the call to >>> platform_driver_unregister() was made conditional upon !HOTPLUG_CPU, >>> but the return value from coretemp_init() was left to indicate an >>> error. This isn't correct, as the negative return value indicates to >>> the module loader that initialization failed, which isn't intended >> >> only !HOTPLUG_CPU can remove the driver. That is what we need to do >> because under the hotplug condition, we need to consider those "offline" >> cpus. I don't understand what you are afraid. Can you give me a scinario ? > > If the driver's init routine returns -ENODEV (like is the case without this > change when HOTPLUG_CPU is enabled and there is no device found), > the platform driver will remain registered, yet the driver memory will > get freed (leaving dangling pointers into the driver's former image). Or Under this condition, I can't fine who frees the memory of the platform driver > in other words - when leaving the driver registered, the return value > of the init function must be zero. Is it mandotary or just some kind of convention ? > > Jan > >>> here and results in dangling pointers. >>> >>> Signed-off-by: Jan Beulich >>> Cc: Chen Gong >>> >>> --- >>> drivers/hwmon/coretemp.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> --- linux-2.6.36-rc4/drivers/hwmon/coretemp.c 2010-09-13 08:45:02.000000000 >> +0200 >>> +++ >> 2.6.36-rc4-x86-coretemp-hotplug-init-return/drivers/hwmon/coretemp.c 2010- >> 09-03 17:54:14.000000000 +0200 >>> @@ -541,16 +541,19 @@ static int __init coretemp_init(void) >>> " has no thermal sensor.\n", c->x86_model); >>> } >>> } >>> + >>> +#ifndef CONFIG_HOTPLUG_CPU >>> if (list_empty(&pdev_list)) { >>> err = -ENODEV; >>> goto exit_driver_unreg; >>> } >>> +#endif >>> >>> register_hotcpu_notifier(&coretemp_cpu_notifier); >>> return 0; >>> >>> -exit_driver_unreg: >>> #ifndef CONFIG_HOTPLUG_CPU >>> +exit_driver_unreg: >>> platform_driver_unregister(&coretemp_driver); >>> #endif >>> exit: >>> >>> >>> >>>