[PATCH] ACPI / button: fix handling lid state changes when input device closed

[dmitry.torokhov@gmail.com]

The original intent of 84d3f6b76447 was to delay evaluating lid state until
all drivers have been loaded, with input device being opened from userspace
serving as a signal for this condition. Let's ensure that state updates
happen even if userspace closed (or in the future inhibited) input device.

Note that if we go through suspend/resume cycle we assume the system has
been fully initialized even if LID input device has not been opened yet.

This has a side-effect of fixing access to input->users outside of
input->mutex protections by the way of eliminating said accesses and using
driver private flag.

Fixes: 84d3f6b76447 ("ACPI / button: Delay acpi_lid_initialize_state() until first user space open")
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/acpi/button.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index 78cfc70cb320..b8dd51d8f96d 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -154,6 +154,7 @@ struct acpi_button {
 	int last_state;
 	ktime_t last_time;
 	bool suspended;
+	bool lid_state_initialized;
 };
 
 static struct acpi_device *lid_device;
@@ -384,6 +385,8 @@ static int acpi_lid_update_state(struct acpi_device *device,
 
 static void acpi_lid_initialize_state(struct acpi_device *device)
 {
+	struct acpi_button *button = acpi_driver_data(device);
+
 	switch (lid_init_state) {
 	case ACPI_BUTTON_LID_INIT_OPEN:
 		(void)acpi_lid_notify_state(device, 1);
@@ -395,13 +398,14 @@ static void acpi_lid_initialize_state(struct acpi_device *device)
 	default:
 		break;
 	}
+
+	button->lid_state_initialized = true;
 }
 
 static void acpi_button_notify(struct acpi_device *device, u32 event)
 {
 	struct acpi_button *button = acpi_driver_data(device);
 	struct input_dev *input;
-	int users;
 
 	switch (event) {
 	case ACPI_FIXED_HARDWARE_EVENT:
@@ -410,10 +414,7 @@ static void acpi_button_notify(struct acpi_device *device, u32 event)
 	case ACPI_BUTTON_NOTIFY_STATUS:
 		input = button->input;
 		if (button->type == ACPI_BUTTON_TYPE_LID) {
-			mutex_lock(&button->input->mutex);
-			users = button->input->users;
-			mutex_unlock(&button->input->mutex);
-			if (users)
+			if (button->lid_state_initialized)
 				acpi_lid_update_state(device, true);
 		} else {
 			int keycode;
@@ -458,7 +459,7 @@ static int acpi_button_resume(struct device *dev)
 	struct acpi_button *button = acpi_driver_data(device);
 
 	button->suspended = false;
-	if (button->type == ACPI_BUTTON_TYPE_LID && button->input->users) {
+	if (button->type == ACPI_BUTTON_TYPE_LID) {
 		button->last_state = !!acpi_lid_evaluate_state(device);
 		button->last_time = ktime_get();
 		acpi_lid_initialize_state(device);
-- 
2.28.0.806.g8561365e88-goog


-- 
Dmitry