Re: [PATCH v3 3/3] acpi : acpi_bus_trim() stops removing devices when failing to remove the device

[Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>]

2012/07/13 1:50, Toshi Kani wrote:
> On Thu, 2012-07-12 at 20:28 +0900, Yasuaki Ishimatsu wrote:
>> acpi_bus_trim() stops removing devices, when acpi_bus_remove() return error
>> number. But acpi_bus_remove() cannot return error number correctly.
>> acpi_bus_remove() only return -EINVAL, when dev argument is NULL. Thus even if
>> device cannot be removed correctly, acpi_bus_trim() ignores and continues to
>> remove devices. acpi_bus_hot_remove_device() uses acpi_bus_trim() for removing
>> devices. Therefore acpi_bus_hot_remove_device() can send "_EJ0" to firmware,
>> even if the device is running on the system. In this case, the system cannot
>> work well. So acpi_bus_trim() should check whether device was removed or not
>> correctly. The patch adds error check into some functions to remove the device.
>>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>
>> ---
>>   drivers/acpi/scan.c    |   15 ++++++++++++---
>>   drivers/base/dd.c      |   22 +++++++++++++++++-----
>>   include/linux/device.h |    2 +-
>>   3 files changed, 30 insertions(+), 9 deletions(-)
>>
>> Index: linux-3.5-rc6/drivers/acpi/scan.c
>> ===================================================================
>> --- linux-3.5-rc6.orig/drivers/acpi/scan.c	2012-07-12 20:11:37.316443808 +0900
>> +++ linux-3.5-rc6/drivers/acpi/scan.c	2012-07-12 20:17:17.927185231 +0900
>> @@ -425,12 +425,17 @@ static int acpi_device_remove(struct dev
>>   {
>>   	struct acpi_device *acpi_dev = to_acpi_device(dev);
>>   	struct acpi_driver *acpi_drv = acpi_dev->driver;
>> +	int ret;
>>
>>   	if (acpi_drv) {
>>   		if (acpi_drv->ops.notify)
>>   			acpi_device_remove_notify_handler(acpi_dev);
>> -		if (acpi_drv->ops.remove)
>> -			acpi_drv->ops.remove(acpi_dev, acpi_dev->removal_type);
>> +		if (acpi_drv->ops.remove) {
>> +			ret = acpi_drv->ops.remove(acpi_dev,
>> +						   acpi_dev->removal_type);
>> +			if (ret)
>> +				return ret;
>> +		}
>>   	}
>>   	acpi_dev->driver = NULL;
>>   	acpi_dev->driver_data = NULL;
>> @@ -1208,11 +1213,15 @@ static int acpi_device_set_context(struc
>>
>>   static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
>>   {
>> +	int ret;
>> +
>>   	if (!dev)
>>   		return -EINVAL;
>>
>>   	dev->removal_type = ACPI_BUS_REMOVAL_EJECT;
>> -	device_release_driver(&dev->dev);
>> +	ret = device_release_driver(&dev->dev);
>> +	if (ret)
>> +		return ret;
>>
>>   	if (!rmdevice)
>>   		return 0;
>> Index: linux-3.5-rc6/drivers/base/dd.c
>> ===================================================================
>> --- linux-3.5-rc6.orig/drivers/base/dd.c	2012-07-12 20:11:37.316443808 +0900
>> +++ linux-3.5-rc6/drivers/base/dd.c	2012-07-12 20:17:17.928185218 +0900
>> @@ -464,9 +464,10 @@ EXPORT_SYMBOL_GPL(driver_attach);
>>    * __device_release_driver() must be called with @dev lock held.
>>    * When called for a USB interface, @dev->parent lock must be held as well.
>>    */
>> -static void __device_release_driver(struct device *dev)
>> +static int __device_release_driver(struct device *dev)
>>   {
>>   	struct device_driver *drv;
>> +	int ret;
>>
>>   	drv = dev->driver;
>>   	if (drv) {
>> @@ -482,9 +483,11 @@ static void __device_release_driver(stru
>>   		pm_runtime_put_sync(dev);
>>
>>   		if (dev->bus && dev->bus->remove)
>> -			dev->bus->remove(dev);
>> +			ret = dev->bus->remove(dev);
>>   		else if (drv->remove)
>> -			drv->remove(dev);
>> +			ret = drv->remove(dev);
>> +		if (ret)
>> +			goto rollback;
>>   		devres_release_all(dev);
>>   		dev->driver = NULL;
>>   		klist_remove(&dev->p->knode_driver);
>> @@ -494,6 +497,12 @@ static void __device_release_driver(stru
>>   						     dev);
>>
>>   	}
>> +
>> +	return ret;
>
> ret is uninitialized when !drv.

Thanks! I'll update it.

>
>> +
>> +rollback:
>> +	driver_sysfs_add(dev);
>> +	return ret;
>>   }
>>
>>   /**
>> @@ -503,16 +512,19 @@ static void __device_release_driver(stru
>>    * Manually detach device from driver.
>>    * When called for a USB interface, @dev->parent lock must be held.
>>    */
>> -void device_release_driver(struct device *dev)
>> +int device_release_driver(struct device *dev)
>
> I agree with this change as driver's remove interface can fail.
> However, there are other callers to this function, which do not check
> the return value.  I suppose there is no impact to the other paths since
> you only changed the CPU hotplug path to fail properly, but please
> confirm this is the case.  I recommend documenting this change to the
> change log.

Thank you for your agreement. As you know, there are other callers. I
believe the patch does not impact to them, since all of them does not
check return value of device_release_driver().

I will write it to the patch.

Thanks,
Yasuaki Ishimatsu


> Thanks,
> -Toshi
>
>
>>   {
>> +	int ret;
>>   	/*
>>   	 * If anyone calls device_release_driver() recursively from
>>   	 * within their ->remove callback for the same device, they
>>   	 * will deadlock right here.
>>   	 */
>>   	device_lock(dev);
>> -	__device_release_driver(dev);
>> +	ret = __device_release_driver(dev);
>>   	device_unlock(dev);
>> +
>> +	return ret;
>>   }
>>   EXPORT_SYMBOL_GPL(device_release_driver);
>>
>> Index: linux-3.5-rc6/include/linux/device.h
>> ===================================================================
>> --- linux-3.5-rc6.orig/include/linux/device.h	2012-07-12 20:11:37.317443779 +0900
>> +++ linux-3.5-rc6/include/linux/device.h	2012-07-12 20:17:17.936185118 +0900
>> @@ -827,7 +827,7 @@ static inline void *dev_get_platdata(con
>>    * for information on use.
>>    */
>>   extern int __must_check device_bind_driver(struct device *dev);
>> -extern void device_release_driver(struct device *dev);
>> +extern int device_release_driver(struct device *dev);
>>   extern int  __must_check device_attach(struct device *dev);
>>   extern int __must_check driver_attach(struct device_driver *drv);
>>   extern int __must_check device_reprobe(struct device *dev);
>>
>
>
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