From 4c014e872e02baa5b0bde38b2b2867ccf1f9df76 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Date: Fri, 5 Mar 2010 13:44:30 -0800
Subject: [PATCH] rtc/mc13783: protect rtc {,un}registration by mc13783 lock
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This is to protect from interrupt handlers using an unregistered rtc
device.

To assert that the reset irq is considered now before the rtc is
registered the corresponding status is checked before.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Cc: Valentin Longchamp <valentin.longchamp@epfl.ch>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Luotao Fu <l.fu@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/rtc/rtc-mc13783.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/rtc/rtc-mc13783.c b/drivers/rtc/rtc-mc13783.c
index 0a978a0e40fc..6a36201178a8 100644
--- a/drivers/rtc/rtc-mc13783.c
+++ b/drivers/rtc/rtc-mc13783.c
@@ -169,6 +169,7 @@ static int __devinit mc13783_rtc_probe(struct platform_device *pdev)
 {
 	int ret;
 	struct mc13783_rtc *priv;
+	int rtcrst_pending;
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -177,8 +178,6 @@ static int __devinit mc13783_rtc_probe(struct platform_device *pdev)
 	priv->mc13783 = dev_get_drvdata(pdev->dev.parent);
 	platform_set_drvdata(pdev, priv);
 
-	priv->valid = 1;
-
 	mc13783_lock(priv->mc13783);
 
 	ret = mc13783_irq_request(priv->mc13783, MC13783_IRQ_RTCRST,
@@ -186,33 +185,37 @@ static int __devinit mc13783_rtc_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_reset_irq_request;
 
+	ret = mc13783_irq_status(priv->mc13783, MC13783_IRQ_RTCRST,
+			NULL, &rtcrst_pending);
+	if (ret)
+		goto err_reset_irq_status;
+
+	priv->valid = !rtcrst_pending;
+
 	ret = mc13783_irq_request_nounmask(priv->mc13783, MC13783_IRQ_1HZ,
 			mc13783_rtc_update_handler, DRIVER_NAME, priv);
 	if (ret)
 		goto err_update_irq_request;
 
-	mc13783_unlock(priv->mc13783);
-
 	priv->rtc = rtc_device_register(pdev->name,
 			&pdev->dev, &mc13783_rtc_ops, THIS_MODULE);
-
 	if (IS_ERR(priv->rtc)) {
 		ret = PTR_ERR(priv->rtc);
 
-		mc13783_lock(priv->mc13783);
-
 		mc13783_irq_free(priv->mc13783, MC13783_IRQ_1HZ, priv);
 err_update_irq_request:
 
+err_reset_irq_status:
+
 		mc13783_irq_free(priv->mc13783, MC13783_IRQ_RTCRST, priv);
 err_reset_irq_request:
 
-		mc13783_unlock(priv->mc13783);
-
 		platform_set_drvdata(pdev, NULL);
 		kfree(priv);
 	}
 
+	mc13783_unlock(priv->mc13783);
+
 	return ret;
 }
 
@@ -220,10 +223,10 @@ static int __devexit mc13783_rtc_remove(struct platform_device *pdev)
 {
 	struct mc13783_rtc *priv = platform_get_drvdata(pdev);
 
-	rtc_device_unregister(priv->rtc);
-
 	mc13783_lock(priv->mc13783);
 
+	rtc_device_unregister(priv->rtc);
+
 	mc13783_irq_free(priv->mc13783, MC13783_IRQ_1HZ, priv);
 	mc13783_irq_free(priv->mc13783, MC13783_IRQ_RTCRST, priv);
 
-- 
2.20.1