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Message-ID: <1342194878.19100.31.camel@misato.fc.hp.com>
Date: Fri, 13 Jul 2012 09:54:38 -0600
From: Toshi Kani <toshi.kani@...com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc: srivatsa.bhat@...ux.vnet.ibm.com, lenb@...nel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] acpi : acpi_bus_trim() stops removing devices
when failing to remove the device
On Fri, 2012-07-13 at 17:53 +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.
>
> device_release_driver() can return error value by the patch. But the change
> does not impact other caller function excluding acpi_bus_trim(), since all
> of them does not check return value of device_releae_driver().
I think potential risk here is that __device_release_driver() now
performs rollback in case of error from driver's remove interface. I
agree with doing the rollback, but this leads to a different situation
if the caller does not check error from device_release_driver() and
proceeds the operation. So, we will need to make sure that:
- Other driver's remove interfaces do not fail (or very unlikely to
fail), or
- If other driver's remove interfaces failed, their end results are no
worse than today.
Thanks,
-Toshi
> 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 2012-07-13 15:10:46.136790418 +0900
> +++ linux-3.5-rc6/drivers/acpi/scan.c 2012-07-13 15:12:41.364349387 +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 2012-07-13 15:10:46.136790418 +0900
> +++ linux-3.5-rc6/drivers/base/dd.c 2012-07-13 15:14:13.895193383 +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 = 0;
>
> 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;
> +
> +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)
> {
> + 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 2012-07-13 15:10:46.137790406 +0900
> +++ linux-3.5-rc6/include/linux/device.h 2012-07-13 15:12:41.371349562 +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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