HID: i2c-hid: add mutex protecting open/close race

We should not enter close function while someone else is in open.
This mutex prevents this race.

There is also no need to override the ret value with -EIO in case of
a failure of i2c_hid_set_power.

Signed-off-by: Benjamin Tissoires <[email protected]>
Reviewed-by: Jean Delvare <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

drivers/hid/i2c-hid/i2c-hid.c

@@ -33,6 +33,7 @@
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/hid.h>
+#include <linux/mutex.h>
 
 #include <linux/i2c/i2c-hid.h>
 
@@ -117,6 +118,8 @@ static const struct i2c_hid_cmd hid_set_power_cmd = { I2C_HID_CMD(0x08) };
  * static const struct i2c_hid_cmd hid_set_protocol_cmd = { I2C_HID_CMD(0x07) };
  */
 
+static DEFINE_MUTEX(i2c_hid_open_mut);
+
 /* The main device structure */
 struct i2c_hid {
  struct i2c_client *client; /* i2c client */
@@ -641,17 +644,20 @@ static int i2c_hid_open(struct hid_device *hid)
 {
  struct i2c_client *client = hid->driver_data;
  struct i2c_hid *ihid = i2c_get_clientdata(client);
- int ret;
+ int ret = 0;
 
+ mutex_lock(&i2c_hid_open_mut);
  if (!hid->open++) {
  ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
  if (ret) {
  hid->open--;
- return -EIO;
+ goto done;
  }
  set_bit(I2C_HID_STARTED, &ihid->flags);
  }
- return 0;
+done:
+ mutex_unlock(&i2c_hid_open_mut);
+ return ret;
 }
 
 static void i2c_hid_close(struct hid_device *hid)
@@ -663,12 +669,14 @@ static void i2c_hid_close(struct hid_device *hid)
  * data acquistion due to a resumption we no longer
  * care about
  */
+ mutex_lock(&i2c_hid_open_mut);
  if (!--hid->open) {
  clear_bit(I2C_HID_STARTED, &ihid->flags);
 
  /* Save some power */
  i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
  }
+ mutex_unlock(&i2c_hid_open_mut);
 }
 
 static int i2c_hid_power(struct hid_device *hid, int lvl)