Re: [PATCH v2] acpi : acpi_bus_trim() stops removing devices when failing to remove the device

[Rafael J. Wysocki]

On Thursday 11 of October 2012 19:12:28 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.
> 
> Vasilis hit the bug at memory hotplug and reported it as follow:
> https://lkml.org/lkml/2012/9/26/318
> 
> 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.
> 
> Applying the patch, acpi_bus_trim() stops removing devices when failing
> to remove the device. But I think there is no impact with the
> exceptionof CPU and Memory hotplug path. Because other device also fails
> but the fail is an irregular case like device is NULL.
> 
> v1->v2
> - add a rollback for reinstalling a notify handler.
> 
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>

Greg, do you think there may be any problems with the changes in dd.c?

Rafael


> ---
>  drivers/acpi/scan.c    |   21 ++++++++++++++++++---
>  drivers/base/dd.c      |   22 +++++++++++++++++-----
>  include/linux/device.h |    2 +-
>  3 files changed, 36 insertions(+), 9 deletions(-)
> 
> Index: linux-3.6/drivers/acpi/scan.c
> ===================================================================
> --- linux-3.6.orig/drivers/acpi/scan.c	2012-10-11 18:31:40.189019503 +0900
> +++ linux-3.6/drivers/acpi/scan.c	2012-10-11 18:42:35.669041641 +0900
> @@ -445,18 +445,29 @@ 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)
> +				goto rollback;
> +		}
>  	}
>  	acpi_dev->driver = NULL;
>  	acpi_dev->driver_data = NULL;
>  
>  	put_device(dev);
>  	return 0;
> +
> +rollback:
> +	if (acpi_drv->ops.notify)
> +		acpi_device_install_notify_handler(acpi_dev);
> +
> +	return ret;
>  }
>  
>  struct bus_type acpi_bus_type = {
> @@ -1226,11 +1237,15 @@ 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-3.6/drivers/base/dd.c
> ===================================================================
> --- linux-3.6.orig/drivers/base/dd.c	2012-10-11 18:31:40.191019505 +0900
> +++ linux-3.6/drivers/base/dd.c	2012-10-11 18:31:46.873020548 +0900
> @@ -475,9 +475,10 @@ 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 = 0;
>  
>  	drv = dev->driver;
>  	if (drv) {
> @@ -493,9 +494,11 @@ 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;
>  		dev_set_drvdata(dev, NULL);
> @@ -506,6 +509,12 @@ static void __device_release_driver(stru
>  						     dev);
>  
>  	}
> +
> +	return ret;
> +
> +rollback:
> +	driver_sysfs_add(dev);
> +	return ret;
>  }
>  
>  /**
> @@ -515,16 +524,19 @@ 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)
>  {
> +	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-3.6/include/linux/device.h
> ===================================================================
> --- linux-3.6.orig/include/linux/device.h	2012-10-11 18:31:40.194019508 +0900
> +++ linux-3.6/include/linux/device.h	2012-10-11 18:31:46.881020556 +0900
> @@ -834,7 +834,7 @@ 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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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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