Re: [PATCH v3 3/3] acpi : acpi_bus_trim() stops removing deviceswhen failing to remove the device

From: Yasuaki Ishimatsu
Date: Fri Jul 13 2012 - 03:16:20 EST

2012/07/13 1:50, Toshi Kani wrote:
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@xxxxxxxxxxxxxx>

---
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.

Thanks! I'll update it.


+
+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.

Thank you for your agreement. As you know, there are other callers. I
believe the patch does not impact to them, since all of them does not
check return value of device_release_driver().

I will write it to the patch.

Thanks,
Yasuaki Ishimatsu


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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