drivers/base: Introduce kill_device() (00289cd8) · Commits · 戴 / test

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: ("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>

drivers/base/core.c

+19 −8

Original line number	Diff line number	Diff line
		@@ -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

include/linux/device.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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);

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