rtc: max8998: Initialize drvdata 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 device or platform drvdata.

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 drvdata 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>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/rtc/rtc-max8998.c b/drivers/rtc/rtc-max8998.c
index 3f7bc6b9fefa..2e48aa604273 100644
--- a/drivers/rtc/rtc-max8998.c
+++ b/drivers/rtc/rtc-max8998.c
@@ -265,6 +265,8 @@ static int __devinit max8998_rtc_probe(struct platform_device *pdev)
         info->rtc = max8998->rtc;
         info->irq = max8998->irq_base + MAX8998_IRQ_ALARM0;
 
+        platform_set_drvdata(pdev, info);
+
         info->rtc_dev = rtc_device_register("max8998-rtc", &pdev->dev,
                         &max8998_rtc_ops, THIS_MODULE);
 
@@ -274,8 +276,6 @@ static int __devinit max8998_rtc_probe(struct platform_device *pdev)
                 goto out_rtc;
         }
 
-        platform_set_drvdata(pdev, info);
-
         ret = request_threaded_irq(info->irq, NULL, max8998_rtc_alarm_irq, 0,
                         "rtc-alarm0", info);
 
@@ -293,6 +293,7 @@ static int __devinit max8998_rtc_probe(struct platform_device *pdev)
         return 0;
 
 out_rtc:
+        platform_set_drvdata(pdev, NULL);
         kfree(info);
         return ret;
 }