rtc: m41t80: Initialize clientdata before registering device

Commit f44f7f96a20 ("RTC: Initialize kernel state from RTC") uncovered
an issue in a number of RTC drivers, where the drivers call
rtc_device_register before initializing the clientdata.

This frequently results in null pointer dereferences when the
rtc_device_register immediately makes use of the rtc device, calling
rtc_read_alarm.

The solution is to ensure the clientdata is initialized prior to registering
the rtc device.

CC: Wolfram Sang <w.sang@pengutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: rtc-linux@googlegroups.com
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index 69fe664a2228a801ede6c1cae5973b551a89f258..eda128fc1d38729ebb1a385c10fd30e6345e852b 100644 (file)
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -783,6 +783,9 @@ static int m41t80_probe(struct i2c_client *client,
                goto exit;
        }
 
+       clientdata->features = id->driver_data;
+       i2c_set_clientdata(client, clientdata);
+
        rtc = rtc_device_register(client->name, &client->dev,
                                  &m41t80_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc)) {
@@ -792,8 +795,6 @@ static int m41t80_probe(struct i2c_client *client,
        }
 
        clientdata->rtc = rtc;
-       clientdata->features = id->driver_data;
-       i2c_set_clientdata(client, clientdata);
 
        /* Make sure HT (Halt Update) bit is cleared */
        rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);