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 <julia@xxxxxxx> >>> >>> 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 <julia@xxxxxxx> >>> >>> --- >>> 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; >>> } >>> >>> >> -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html