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

From: Yasuaki Ishimatsu
Date: Fri Oct 12 2012 - 00:32:15 EST

Hi Toshi,

2012/10/11 22:58, Toshi Kani wrote:
On Thu, 2012-10-11 at 19:12 +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.

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>

Thanks for the update. Looks good.

Reviewed-by: Toshi Kani <toshi.kani@xxxxxx>

Thank you for reviewing.

Thanks,
Yasauaki Ishimatsu

-Toshi


---
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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