linux-kernel - [PATCH 4.19 120/191] ACPI: button: fix handling lid state changes when input device closed

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Message-Id: <20201103203244.537854736@linuxfoundation.org>
Date:   Tue,  3 Nov 2020 21:36:52 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.19 120/191] ACPI: button: fix handling lid state changes when input device closed

From: dmitry.torokhov@...il.com <dmitry.torokhov@...il.com>

commit 21988a8e51479ceffe7b0568b170effabb708dfe upstream.

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@...il.com>
Reviewed-by: Hans de Goede <hdegoede@...hat.com>
Cc: 4.15+ <stable@...r.kernel.org> # 4.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/acpi/button.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -149,6 +149,7 @@ struct acpi_button {
 	int last_state;
 	ktime_t last_time;
 	bool suspended;
+	bool lid_state_initialized;
 };
 
 static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
@@ -404,6 +405,8 @@ static int acpi_lid_update_state(struct
 
 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);
@@ -415,13 +418,14 @@ static void acpi_lid_initialize_state(st
 	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:
@@ -430,10 +434,7 @@ static void acpi_button_notify(struct ac
 	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;
@@ -478,7 +479,7 @@ static int acpi_button_resume(struct 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);