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drivers/base: Introduce kill_device()

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The libnvdimm subsystem arranges for devices to be destroyed as a result
of a sysfs operation. Since device_unregister() cannot be called from
an actively running sysfs attribute of the same device libnvdimm
arranges for device_unregister() to be performed in an out-of-line async
context.

The driver core maintains a 'dead' state for coordinating its own racing
async registration / de-registration requests. Rather than add local
'dead' state tracking infrastructure to libnvdimm device objects, export
the existing state tracking via a new kill_device() helper.

The kill_device() helper simply marks the device as dead, i.e. that it
is on its way to device_del(), or returns that the device was already
dead. This can be used in advance of calling device_unregister() for
subsystems like libnvdimm that might need to handle multiple user
threads racing to delete a device.

This refactoring does not change any behavior, but it is a pre-requisite
for follow-on fixes and therefore marked for -stable.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Fixes: 4d88a97aa9 ("libnvdimm, nvdimm: dimm driver and base libnvdimm device-driver...")
Cc: <stable@vger.kernel.org>
Tested-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/156341207332.292348.14959761496009347574.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2019-07-17 18:07:53 -07:00
parent d1fdb6d8f6
commit 00289cd876
2 changed files with 20 additions and 8 deletions
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27
drivers/base/core.c
View File

@ -2211,6 +2211,24 @@ void put_device(struct device *dev)
}
EXPORT_SYMBOL_GPL(put_device);
bool kill_device(struct device *dev)
{
/*
* Require the device lock and set the "dead" flag to guarantee that
* the update behavior is consistent with the other bitfields near
* it and that we cannot have an asynchronous probe routine trying
* to run while we are tearing out the bus/class/sysfs from
* underneath the device.
*/
lockdep_assert_held(&dev->mutex);
if (dev->p->dead)
return false;
dev->p->dead = true;
return true;
}
EXPORT_SYMBOL_GPL(kill_device);
/**
* device_del - delete device from system.
* @dev: device.
@ -2230,15 +2248,8 @@ void device_del(struct device *dev)
struct kobject *glue_dir = NULL;
struct class_interface *class_intf;
/*
* Hold the device lock and set the "dead" flag to guarantee that
* the update behavior is consistent with the other bitfields near
* it and that we cannot have an asynchronous probe routine trying
* to run while we are tearing out the bus/class/sysfs from
* underneath the device.
*/
device_lock(dev);
dev->p->dead = true;
kill_device(dev);
device_unlock(dev);
/* Notify clients of device removal. This call must come

1
include/linux/device.h
View File

@ -1373,6 +1373,7 @@ extern int (*platform_notify_remove)(struct device *dev);
*/
extern struct device *get_device(struct device *dev);
extern void put_device(struct device *dev);
extern bool kill_device(struct device *dev);
#ifdef CONFIG_DEVTMPFS
extern int devtmpfs_create_node(struct device *dev);