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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>
This commit is contained in:
Benjamin Tissoires 2012-12-12 18:00:02 +01:00 committed by Jiri Kosina
parent 9afd09a1db
commit 7a7d6d9c5f
1 changed files with 11 additions and 3 deletions
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14
drivers/hid/i2c-hid/i2c-hid.c
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@ -33,6 +33,7 @@
#include <linux/jiffies.h> #include <linux/jiffies.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/hid.h> #include <linux/hid.h>
#include <linux/mutex.h>
#include <linux/i2c/i2c-hid.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 const struct i2c_hid_cmd hid_set_protocol_cmd = { I2C_HID_CMD(0x07) };
*/ */
static DEFINE_MUTEX(i2c_hid_open_mut);
/* The main device structure */ /* The main device structure */
struct i2c_hid { struct i2c_hid {
struct i2c_client *client; /* i2c client */ 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_client *client = hid->driver_data;
struct i2c_hid *ihid = i2c_get_clientdata(client); struct i2c_hid *ihid = i2c_get_clientdata(client);
int ret; int ret = 0;
mutex_lock(&i2c_hid_open_mut);
if (!hid->open++) { if (!hid->open++) {
ret = i2c_hid_set_power(client, I2C_HID_PWR_ON); ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
if (ret) { if (ret) {
hid->open--; hid->open--;
return -EIO; goto done;
} }
set_bit(I2C_HID_STARTED, &ihid->flags); 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) 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 * data acquistion due to a resumption we no longer
* care about * care about
*/ */
mutex_lock(&i2c_hid_open_mut);
if (!--hid->open) { if (!--hid->open) {
clear_bit(I2C_HID_STARTED, &ihid->flags); clear_bit(I2C_HID_STARTED, &ihid->flags);
/* Save some power */ /* Save some power */
i2c_hid_set_power(client, I2C_HID_PWR_SLEEP); 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) static int i2c_hid_power(struct hid_device *hid, int lvl)