Merge back ACPI namespace scan code changes for v4.12.

Documentation/ABI/obsolete/sysfs-firmware-acpi

+What:		/sys/firmware/acpi/hotplug/force_remove
+Date:		Mar 2017
+Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+		Since the force_remove is inherently broken and dangerous to
+		use for some hotplugable resources like memory (because ignoring
+		the offline failure might lead to memory corruption and crashes)
+		enabling this knob is not safe and thus unsupported.

Documentation/ABI/testing/sysfs-firmware-acpi

@@ -44,16 +44,6 @@ Description:
 		or 0 (unset).  Attempts to write any other values to it will
 		cause -EINVAL to be returned.
 
-What:		/sys/firmware/acpi/hotplug/force_remove
-Date:		May 2013
-Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-Description:
-		The number in this file (0 or 1) determines whether (1) or not
-		(0) the ACPI subsystem will allow devices to be hot-removed even
-		if they cannot be put offline gracefully (from the kernel's
-		viewpoint).  That number can be changed by writing a boolean
-		value to this file.
-
 What:		/sys/firmware/acpi/interrupts/
 Date:		February 2008
 Contact:	Len Brown <lenb@kernel.org>

drivers/acpi/internal.h

@@ -65,8 +65,6 @@ static inline void acpi_cmos_rtc_init(void) {}
 #endif
 int acpi_rev_override_setup(char *str);
 
-extern bool acpi_force_hot_remove;
-
 void acpi_sysfs_add_hotplug_profile(struct acpi_hotplug_profile *hotplug,
 				    const char *name);
 int acpi_scan_add_handler_with_hotplug(struct acpi_scan_handler *handler,

drivers/acpi/scan.c

@@ -30,12 +30,6 @@ extern struct acpi_device *acpi_root;
 
 #define INVALID_ACPI_HANDLE	((acpi_handle)empty_zero_page)
 
-/*
- * If set, devices will be hot-removed even if they cannot be put offline
- * gracefully (from the kernel's standpoint).
- */
-bool acpi_force_hot_remove;
-
 static const char *dummy_hid = "device";
 
 static LIST_HEAD(acpi_dep_list);
@@ -170,9 +164,6 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data,
 			pn->put_online = false;
 		}
 		ret = device_offline(pn->dev);
-		if (acpi_force_hot_remove)
-			continue;
-
 		if (ret >= 0) {
 			pn->put_online = !ret;
 		} else {
@@ -241,11 +232,11 @@ static int acpi_scan_try_to_offline(struct acpi_device *device)
 		acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
 				    NULL, acpi_bus_offline, (void *)true,
 				    (void **)&errdev);
-		if (!errdev || acpi_force_hot_remove)
+		if (!errdev)
 			acpi_bus_offline(handle, 0, (void *)true,
 					 (void **)&errdev);
 
-		if (errdev && !acpi_force_hot_remove) {
+		if (errdev) {
 			dev_warn(errdev, "Offline failed.\n");
 			acpi_bus_online(handle, 0, NULL, NULL);
 			acpi_walk_namespace(ACPI_TYPE_ANY, handle,
@@ -263,8 +254,7 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
 	unsigned long long sta;
 	acpi_status status;
 
-	if (device->handler && device->handler->hotplug.demand_offline
-	    && !acpi_force_hot_remove) {
+	if (device->handler && device->handler->hotplug.demand_offline) {
 		if (!acpi_scan_is_offline(device, true))
 			return -EBUSY;
 	} else {

drivers/acpi/sysfs.c

@@ -921,7 +921,7 @@ void acpi_sysfs_add_hotplug_profile(struct acpi_hotplug_profile *hotplug,
 static ssize_t force_remove_show(struct kobject *kobj,
 				 struct kobj_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", !!acpi_force_hot_remove);
+	return sprintf(buf, "%d\n", 0);
 }
 
 static ssize_t force_remove_store(struct kobject *kobj,
@@ -935,9 +935,10 @@ static ssize_t force_remove_store(struct kobject *kobj,
 	if (ret < 0)
 		return ret;
 
-	lock_device_hotplug();
-	acpi_force_hot_remove = val;
-	unlock_device_hotplug();
+	if (val) {
+		pr_err("Enabling force_remove is not supported anymore. Please report to linux-acpi@vger.kernel.org if you depend on this functionality\n");
+		return -EINVAL;
+	}
 	return size;
 }