Re: [PATCH v2] HID: i2c-hid: add mutex protecting open/close race
From: Jiri Kosina <hidden>
Date: 2012-12-12 17:27:32
Also in:
linux-i2c, lkml
On Wed, 12 Dec 2012, Benjamin Tissoires wrote:
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 <redacted> Reviewed-by: Jean Delvare <redacted> --- Changes in v2: * add mutex.h
Applied, thanks.
quoted hunk ↗ jump to hunk
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
-- Jiri Kosina SUSE Labs