[PATCH AUTOSEL 5.4 050/205] ACPI: platform: Unregister stale platform devices

[PATCH AUTOSEL 5.4 050/205] ACPI: platform: Unregister stale platform devices

[Sasha Levin]

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

[ Upstream commit cb0701acfa7e3fe9e919cf2aa2aa939b7fd603c2 ]

When commit 68bdb6773289 ("ACPI: add support for ACPI reconfiguration
notifiers") introduced reconfiguration notifiers, it missed the point
that the ACPI table, which might be loaded and then unloaded via
ConfigFS, could contain devices that were not enumerated by their
parents.

In such cases, the stale platform device is dangling in the system
while the rest of the devices from the same table are already gone.

Introduce acpi_platform_device_remove_notify() notifier that, in
similar way to I²C or SPI buses, unregisters the platform devices
on table removal event.

Fixes: 68bdb6773289 ("ACPI: add support for ACPI reconfiguration notifiers")
Depends-on: 00500147cbd3 ("drivers: Introduce device lookup variants by ACPI_COMPANION device")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ rjw: Changelog & function rename ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/acpi/acpi_platform.c | 43 ++++++++++++++++++++++++++++++++++++
 drivers/acpi/scan.c          |  1 +
 2 files changed, 44 insertions(+)

diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
index 00ec4f2bf015..c05050f474cd 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -31,6 +31,44 @@ static const struct acpi_device_id forbidden_id_list[] = {
 	{"", 0},
 };
 
+static struct platform_device *acpi_platform_device_find_by_companion(struct acpi_device *adev)
+{
+	struct device *dev;
+
+	dev = bus_find_device_by_acpi_dev(&platform_bus_type, adev);
+	return dev ? to_platform_device(dev) : NULL;
+}
+
+static int acpi_platform_device_remove_notify(struct notifier_block *nb,
+					      unsigned long value, void *arg)
+{
+	struct acpi_device *adev = arg;
+	struct platform_device *pdev;
+
+	switch (value) {
+	case ACPI_RECONFIG_DEVICE_ADD:
+		/* Nothing to do here */
+		break;
+	case ACPI_RECONFIG_DEVICE_REMOVE:
+		if (!acpi_device_enumerated(adev))
+			break;
+
+		pdev = acpi_platform_device_find_by_companion(adev);
+		if (!pdev)
+			break;
+
+		platform_device_unregister(pdev);
+		put_device(&pdev->dev);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block acpi_platform_notifier = {
+	.notifier_call = acpi_platform_device_remove_notify,
+};
+
 static void acpi_platform_fill_resource(struct acpi_device *adev,
 	const struct resource *src, struct resource *dest)
 {
@@ -130,3 +168,8 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev,
 	return pdev;
 }
 EXPORT_SYMBOL_GPL(acpi_create_platform_device);
+
+void __init acpi_platform_init(void)
+{
+	acpi_reconfig_notifier_register(&acpi_platform_notifier);
+}
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index aad6be5c0af0..915650bf519f 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2174,6 +2174,7 @@ int __init acpi_scan_init(void)
 	acpi_pci_root_init();
 	acpi_pci_link_init();
 	acpi_processor_init();
+	acpi_platform_init();
 	acpi_lpss_init();
 	acpi_apd_init();
 	acpi_cmos_rtc_init();
-- 
2.20.1