FAILED: patch "[PATCH] drivers/base: Introduce kill_device()" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jul 29, 2019

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2019-07-29 17:42 UTC #0 lore raw

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 00289cd87676e14913d2d8492d1ce05c4baafdae Mon Sep 17 00:00:00 2001
From: Dan Williams <[email protected]>
Date: Wed, 17 Jul 2019 18:07:53 -0700
Subject: [PATCH] drivers/base: Introduce kill_device()

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 <[email protected]>

Cc "Rafael J. Wysocki" <[email protected]>

Fixes 4d88a97aa9e8 ("libnvdimm, nvdimm: dimm driver and base libnvdimm device-driver...")

Cc <[email protected]>

Tested-by Jane Chu <[email protected]>

Reviewed-by Greg Kroah-Hartman <[email protected]>

Link https://lore.kernel.org/r/156341207332.292348.14959761496009347574.stgit@dwillia2-desk3.amr.corp.intel.com open here

Signed-off-by Dan Williams <[email protected]>

drivers/base/core.c +19 -8

index fd7511e04e62..eaf3aa0cb803 100644
@@ -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

index e85264fb6616..0da5c67f6be1 100644
@@ -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);