[PATCH 1/2] rtc: mv: fix potential race condition

[PATCH 1/2] rtc: mv: fix potential race condition

[alexandre.belloni]

From: Alexandre Belloni <alexandre.belloni@bootlin.com>

Since the driver allocates the IRQ using devm_request_irq(), this means the
IRQ is going to be automatically unregistered by devres after
mv_rtc_remove() returns.

However, mv_rtc_remove() explicitly disables the hardware clock before
devres teardown happens so the interrupt handler may run while the clock is
disabled leading to a possible bus hang when accessing registers.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-mv.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
index f88976fd6d5d..c0f1bcd838e3 100644
--- a/drivers/rtc/rtc-mv.c
+++ b/drivers/rtc/rtc-mv.c
@@ -219,17 +219,15 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(pdata->ioaddr))
 		return PTR_ERR(pdata->ioaddr);
 
-	pdata->clk = devm_clk_get(&pdev->dev, NULL);
-	/* Not all SoCs require a clock.*/
-	if (!IS_ERR(pdata->clk))
-		clk_prepare_enable(pdata->clk);
+	pdata->clk = devm_clk_get_optional_prepared(&pdev->dev, NULL);
+	if (IS_ERR(pdata->clk))
+		return PTR_ERR(pdata->clk);
 
 	/* make sure the 24 hour mode is enabled */
 	rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
 	if (rtc_time & RTC_HOURS_12H_MODE) {
 		dev_err(&pdev->dev, "12 Hour mode is enabled but not supported.\n");
-		ret = -EINVAL;
-		goto out;
+		return  -EINVAL;
 	}
 
 	/* make sure it is actually functional */
@@ -238,8 +236,7 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
 		rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
 		if (rtc_time == 0x01000000) {
 			dev_err(&pdev->dev, "internal RTC not ticking\n");
-			ret = -ENODEV;
-			goto out;
+			return -ENODEV;
 		}
 	}
 
@@ -249,8 +246,7 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
 
 	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(pdata->rtc)) {
-		ret = PTR_ERR(pdata->rtc);
-		goto out;
+		return PTR_ERR(pdata->rtc);
 	}
 
 	if (pdata->irq >= 0) {
@@ -275,9 +271,6 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
 	ret = devm_rtc_register_device(pdata->rtc);
 	if (!ret)
 		return 0;
-out:
-	if (!IS_ERR(pdata->clk))
-		clk_disable_unprepare(pdata->clk);
 
 	return ret;
 }
@@ -288,9 +281,6 @@ static void __exit mv_rtc_remove(struct platform_device *pdev)
 
 	if (pdata->irq >= 0)
 		device_init_wakeup(&pdev->dev, false);
-
-	if (!IS_ERR(pdata->clk))
-		clk_disable_unprepare(pdata->clk);
 }
 
 #ifdef CONFIG_OF
-- 
2.54.0

[PATCH 2/2] rtc: mv: remove mv_rtc_remove

[alexandre.belloni]

From: Alexandre Belloni <alexandre.belloni@bootlin.com>

Use devm_device_init_wakeup() so we can avoid having to explicitly teardown
of module removal.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-mv.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
index c0f1bcd838e3..db64c459ee19 100644
--- a/drivers/rtc/rtc-mv.c
+++ b/drivers/rtc/rtc-mv.c
@@ -260,7 +260,7 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
 	}
 
 	if (pdata->irq >= 0)
-		device_init_wakeup(&pdev->dev, true);
+		devm_device_init_wakeup(&pdev->dev);
 	else
 		clear_bit(RTC_FEATURE_ALARM, pdata->rtc->features);
 
@@ -275,14 +275,6 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static void __exit mv_rtc_remove(struct platform_device *pdev)
-{
-	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
-
-	if (pdata->irq >= 0)
-		device_init_wakeup(&pdev->dev, false);
-}
-
 #ifdef CONFIG_OF
 static const struct of_device_id rtc_mv_of_match_table[] = {
 	{ .compatible = "marvell,orion-rtc", },
@@ -313,14 +305,7 @@ static int mv_rtc_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(mv_rtc_pm_ops, mv_rtc_suspend, mv_rtc_resume);
 
-/*
- * mv_rtc_remove() lives in .exit.text. For drivers registered via
- * module_platform_driver_probe() this is ok because they cannot get unbound at
- * runtime. So mark the driver struct with __refdata to prevent modpost
- * triggering a section mismatch warning.
- */
-static struct platform_driver mv_rtc_driver __refdata = {
-	.remove		= __exit_p(mv_rtc_remove),
+static struct platform_driver mv_rtc_driver = {
 	.driver		= {
 		.name	= "rtc-mv",
 		.of_match_table = of_match_ptr(rtc_mv_of_match_table),
-- 
2.54.0