Re: [PATCH 2/4] platform/x86: xiaomi-wmi: Fix race condition when reporting key events

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


Am 28.03.24 um 03:58 schrieb Kuppuswamy Sathyanarayanan:

On 3/27/24 6:23 PM, Armin Wolf wrote:
Multiple WMI events can be received concurrently, so multiple instances
of xiaomi_wmi_notify() can be active at the same time. Since the input
device is shared between those handlers, the key input sequence can be
Since locking is needed for all notify related calls in all WMI drivers,
is there a generic way to add this support in WMI core driver? Like
defining some common function which will hold the lock and call
driver specific notify handler? I am just thinking aloud.. If it is not
feasible, then it is fine.


actually, not all notify-related calls need locking. It just so happens that
input drivers must protect their key sequence, other WMI drivers might not need
to use any locking at all.

I would prefer if the WMI driver does the locking, so it can be optimized for
each WMI driver.

Armin Wolf

Fix this by protecting the key input sequence with a mutex.

Compile-tested only.

Fixes: edb73f4f0247 ("platform/x86: wmi: add Xiaomi WMI key driver")
Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
  drivers/platform/x86/xiaomi-wmi.c | 18 ++++++++++++++++++
  1 file changed, 18 insertions(+)

diff --git a/drivers/platform/x86/xiaomi-wmi.c b/drivers/platform/x86/xiaomi-wmi.c
index 1f5f108d87c0..7efbdc111803 100644
--- a/drivers/platform/x86/xiaomi-wmi.c
+++ b/drivers/platform/x86/xiaomi-wmi.c
@@ -2,8 +2,10 @@
  /* WMI driver for Xiaomi Laptops */

  #include <linux/acpi.h>
+#include <linux/device.h>
  #include <linux/input.h>
  #include <linux/module.h>
+#include <linux/mutex.h>
  #include <linux/wmi.h>

  #include <uapi/linux/input-event-codes.h>
@@ -20,12 +22,21 @@

  struct xiaomi_wmi {
  	struct input_dev *input_dev;
+	struct mutex key_lock;	/* Protects the key event sequence */
  	unsigned int key_code;

+static void xiaomi_mutex_destroy(void *data)
+	struct mutex *lock = data;
+	mutex_destroy(lock);
  static int xiaomi_wmi_probe(struct wmi_device *wdev, const void *context)
  	struct xiaomi_wmi *data;
+	int ret;

  	if (wdev == NULL || context == NULL)
  		return -EINVAL;
@@ -35,6 +46,11 @@ static int xiaomi_wmi_probe(struct wmi_device *wdev, const void *context)
  		return -ENOMEM;
  	dev_set_drvdata(&wdev->dev, data);

+	mutex_init(&data->key_lock);
+	ret = devm_add_action_or_reset(&wdev->dev, xiaomi_mutex_destroy, &data->key_lock);
+	if (ret < 0)
+		return ret;
  	data->input_dev = devm_input_allocate_device(&wdev->dev);
  	if (data->input_dev == NULL)
  		return -ENOMEM;
@@ -59,10 +75,12 @@ static void xiaomi_wmi_notify(struct wmi_device *wdev, union acpi_object *dummy)
  	if (data == NULL)

+	mutex_lock(&data->key_lock);
  	input_report_key(data->input_dev, data->key_code, 1);
  	input_report_key(data->input_dev, data->key_code, 0);
+	mutex_unlock(&data->key_lock);

  static const struct wmi_device_id xiaomi_wmi_id_table[] = {

[Index of Archives]     [Linux Kernel Development]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux