drivers/rtc/rtc-r9701.c: fix crash in r9701_remove()

If probing the RTC didn't succeed due to failed RTC register access, the RTC device will be unregistered. Then, when removing the module r9701_remove() causes a kernel crash while trying to unregister a not registered RTC device. Fix this by doing RTC register access test before RTC device registration. Signed-off-by: Anatolij Gustschin <[email protected]> Cc: Alessandro Zummo <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ambv · Mar 5, 2012 · 73737b8 · 73737b8
1 parent 22ea71d
commit 73737b8
Showing 1 changed file with 7 additions and 7 deletions.
diff --git a/drivers/rtc/rtc-r9701.c b/drivers/rtc/rtc-r9701.c
@@ -125,20 +125,20 @@ static int __devinit r9701_probe(struct spi_device *spi)
 	unsigned char tmp;
 	int res;
 
+	tmp = R100CNT;
+	res = read_regs(&spi->dev, &tmp, 1);
+	if (res || tmp != 0x20) {
+		dev_err(&spi->dev, "cannot read RTC register\n");
+		return -ENODEV;
+	}
+
 	rtc = rtc_device_register("r9701",
 				&spi->dev, &r9701_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 
 	dev_set_drvdata(&spi->dev, rtc);
 
-	tmp = R100CNT;
-	res = read_regs(&spi->dev, &tmp, 1);
-	if (res || tmp != 0x20) {
-		rtc_device_unregister(rtc);
-		return res;
-	}
-
 	return 0;
 }