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Date: Thu, 12 Jul 2012 10:50:15 -0600
From: Toshi Kani <toshi.kani@...com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
lenb@...nel.org, srivatsa.bhat@...ux.vnet.ibm.com
Subject: Re: [PATCH v3 3/3] acpi : acpi_bus_trim() stops removing devices
when failing to remove the device
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@...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.
> +
> +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.
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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