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 <benjamin.tissoires@gmail.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 6e1774c..9ef2224 100644 (file)
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/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)