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Message-ID: <1846185.MSykHDcMmb@vostro.rjw.lan>
Date: Fri, 19 Oct 2012 06:29:52 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
toshi.kani@...com, lenb@...nel.org, wency@...fujitsu.com,
vasilis.liaskovitis@...fitbricks.com
Subject: Re: [PATCH v2] acpi : acpi_bus_trim() stops removing devices when failing to remove the device
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@...fujitsu.com>
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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