From 6406d96e74a59ae98cf3197a9f9498e14d2df562 Mon Sep 17 00:00:00 2001 From: Steve Twiss Date: Thu, 14 Apr 2016 12:04:54 +0100 Subject: [PATCH] rtc: da9053: fix access ordering error during RTC interrupt at system power on This fix alters the ordering of the IRQ and device registrations in the RTC driver probe function. This change will apply to the RTC driver that supports both DA9052 and DA9053 PMICs. A problem could occur with the existing RTC driver if: A system is started from a cold boot using the PMIC RTC IRQ to initiate a power on operation. For instance, if an RTC alarm is used to start a platform from power off. The existing driver IRQ is requested before the device has been properly registered. i.e. ret = da9052_request_irq() comes before rtc->rtc = devm_rtc_device_register(); In this case, an interrupt exists before the device has been registered and the IRQ handler can be called immediately: this can happen be before the memory for rtc->rtc has been allocated. The IRQ handler da9052_rtc_irq() contains the function call: rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF); which in turn tries to access the unavailable rtc->rtc. The fix is to reorder the functions inside the RTC probe. The IRQ is requested after the RTC device resource has been registered so that da9052_request_irq() is the last thing to happen. Signed-off-by: Steve Twiss Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-da9052.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/rtc/rtc-da9052.c b/drivers/rtc/rtc-da9052.c index 1ba4371cbc2d..a20bcf0e33cd 100644 --- a/drivers/rtc/rtc-da9052.c +++ b/drivers/rtc/rtc-da9052.c @@ -302,6 +302,13 @@ static int da9052_rtc_probe(struct platform_device *pdev) if (ret != 0) rtc_err(rtc, "Failed to disable TICKS: %d\n", ret); + device_init_wakeup(&pdev->dev, true); + rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name, + &da9052_rtc_ops, THIS_MODULE); + + if (IS_ERR(rtc->rtc)) + return PTR_ERR(rtc->rtc); + ret = da9052_request_irq(rtc->da9052, DA9052_IRQ_ALARM, "ALM", da9052_rtc_irq, rtc); if (ret != 0) { @@ -309,11 +316,7 @@ static int da9052_rtc_probe(struct platform_device *pdev) return ret; } - device_init_wakeup(&pdev->dev, true); - - rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name, - &da9052_rtc_ops, THIS_MODULE); - return PTR_ERR_OR_ZERO(rtc->rtc); + return 0; } static struct platform_driver da9052_rtc_driver = { -- 2.20.1