From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030806Ab2CNNPQ (ORCPT ); Wed, 14 Mar 2012 09:15:16 -0400 Received: from e28smtp05.in.ibm.com ([122.248.162.5]:58044 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964930Ab2CNNPN (ORCPT ); Wed, 14 Mar 2012 09:15:13 -0400 Message-ID: <4F6093FD.2040209@linux.vnet.ibm.com> Date: Wed, 14 Mar 2012 18:20:05 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux i686; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 MIME-Version: 1.0 To: Julia Lawall CC: Len Brown , kernel-janitors@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Julia Lawall , Deepthi Dharwar , Venkatesh Pallipadi , trenn@suse.de, bhelgaas@google.com Subject: Re: [PATCH] drivers/acpi/processor_driver.c: add missing kfree References: <1331399145-6508-1-git-send-email-Julia.Lawall@lip6.fr> <4F608251.9030307@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 12031412-8256-0000-0000-000001A261C9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/14/2012 06:02 PM, Julia Lawall wrote: > > > On Wed, 14 Mar 2012, Srivatsa S. Bhat wrote: > >> On 03/10/2012 10:35 PM, Julia Lawall wrote: >> >>> From: Julia Lawall >>> >>> The function acpi_processor_add is stored in the ops.add field of a >>> acpi_driver structure. This function is then called in >>> acpi_bus_driver_init. On failure, this function clears the field >>> device->driver_data, but does not free its contents. Thus the free >>> has to >>> be done by the add function. In acpi_processor_add, the corresponding >>> value is pr. This value is currently freed on failure before storing >>> it in >>> device->driver_data, but not after. This free is added in the error >>> handling code at the end of the function. The static global variable >> >> >> "static global variable"?? never heard that one before ;-) >> Maybe you meant "per_cpu variable processors".. >> >>> processors is also cleared so that it does not refer to a dangling >>> pointer. >>> processor_device_array is cleared as well. >>> >>> Signed-off-by: Julia Lawall >>> >>> --- >>> This is only compile tested. In particular, I don't know if it is >>> correct >>> to add per_cpu(processor_device_array, pr->id) = NULL;. >> >> >> No, you shouldn't set it to NULL. processor_device_array was added to >> check >> for buggy BIOSes and return gracefully. Check commit cd8e2b48d (and >> also the >> bugzilla link in that commit). >> >> To have a robust check for buggy BIOSes, we must let it be as it is, >> even if >> it is a stale pointer. That way we can still catch subsequent calls to >> this >> function with the same acpi id (because of a buggy BIOS) and take >> appropriate >> actions. >> >> Other than that, the patch looks good to me. > > Thanks for the feedback. Just to be clear, I should keep > > +err_clear_processors: > + per_cpu(processors, pr->id) = NULL; > > and just drop: > > + per_cpu(processor_device_array, pr->id) = NULL; > Yep, that's right. But in fact, you can even do better than that... That is, drop the above line and put a comment that explains why we shouldn't set per_cpu(processor_device_array..) to NULL. That way, in future people will know that setting it to NULL was left out on purpose. And please adjust the commit message too, as I pointed in my previous mail :-) Regards, Srivatsa S. Bhat >>> >>> drivers/acpi/processor_driver.c | 12 ++++++++---- >>> 1 file changed, 8 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/acpi/processor_driver.c >>> b/drivers/acpi/processor_driver.c >>> index 2801b41..9bb0017 100644 >>> --- a/drivers/acpi/processor_driver.c >>> +++ b/drivers/acpi/processor_driver.c >>> @@ -536,8 +536,8 @@ static int __cpuinit acpi_processor_add(struct >>> acpi_device *device) >>> return -ENOMEM; >>> >>> if (!zalloc_cpumask_var(&pr->throttling.shared_cpu_map, >>> GFP_KERNEL)) { >>> - kfree(pr); >>> - return -ENOMEM; >>> + result = -ENOMEM; >>> + goto err_free_pr; >>> } >>> >>> pr->handle = device->handle; >>> @@ -577,7 +577,7 @@ static int __cpuinit acpi_processor_add(struct >>> acpi_device *device) >>> dev = get_cpu_device(pr->id); >>> if (sysfs_create_link(&device->dev.kobj, &dev->kobj, "sysdev")) { >>> result = -EFAULT; >>> - goto err_free_cpumask; >>> + goto err_clear_processors; >>> } >>> >>> /* >>> @@ -595,9 +595,13 @@ static int __cpuinit acpi_processor_add(struct >>> acpi_device *device) >>> >>> err_remove_sysfs: >>> sysfs_remove_link(&device->dev.kobj, "sysdev"); >>> +err_clear_processors: >>> + per_cpu(processors, pr->id) = NULL; >>> + per_cpu(processor_device_array, pr->id) = NULL; >>> err_free_cpumask: >>> free_cpumask_var(pr->throttling.shared_cpu_map); >>> - >>> +err_free_pr: >>> + kfree(pr); >>> return result; >>> } >>> >>> >>