linux-kernel - [PATCH 03/11] rtc: ep93xx: Initialize drvdata before registering device

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Date:	Fri,  6 May 2011 18:20:46 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	Wolfram Sang <w.sang@...gutronix.de>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Thomas Gleixner <tglx@...utronix.de>,
	rtc-linux@...glegroups.com, John Stultz <john.stultz@...aro.org>
Subject: [PATCH 03/11] rtc: ep93xx: Initialize drvdata before registering device

From: Wolfram Sang <w.sang@...gutronix.de>

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: Alessandro Zummo <a.zummo@...ertech.it>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: rtc-linux@...glegroups.com
Signed-off-by: Wolfram Sang <w.sang@...gutronix.de>
[Fixed up commit log -jstultz]
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/rtc/rtc-ep93xx.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-ep93xx.c b/drivers/rtc/rtc-ep93xx.c
index 11ae64d..335551d 100644
--- a/drivers/rtc/rtc-ep93xx.c
+++ b/drivers/rtc/rtc-ep93xx.c
@@ -151,6 +151,7 @@ static int __init ep93xx_rtc_probe(struct platform_device *pdev)
 		return -ENXIO;
 
 	pdev->dev.platform_data = ep93xx_rtc;
+	platform_set_drvdata(pdev, rtc);
 
 	rtc = rtc_device_register(pdev->name,
 				&pdev->dev, &ep93xx_rtc_ops, THIS_MODULE);
@@ -159,8 +160,6 @@ static int __init ep93xx_rtc_probe(struct platform_device *pdev)
 		goto exit;
 	}
 
-	platform_set_drvdata(pdev, rtc);
-
 	err = sysfs_create_group(&pdev->dev.kobj, &ep93xx_rtc_sysfs_files);
 	if (err)
 		goto fail;
@@ -168,9 +167,9 @@ static int __init ep93xx_rtc_probe(struct platform_device *pdev)
 	return 0;
 
 fail:
-	platform_set_drvdata(pdev, NULL);
 	rtc_device_unregister(rtc);
 exit:
+	platform_set_drvdata(pdev, NULL);
 	pdev->dev.platform_data = NULL;
 	return err;
 }
-- 
1.7.3.2.146.gca209

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