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

[dmitry . torokhov]

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.torok...@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