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Subject[PATCH v2] HID: i2c-hid: add mutex protecting open/close race
Date
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>
---

Changes in v2:
* add mutex.h

Cheers,
Benjamin

drivers/hid/i2c-hid/i2c-hid.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 6e1774c..9ef22244 100644
--- 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)
--
1.8.0.2


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