[PATCH 1/2] rtc: ds1685: fix possible race condition

From: Alexandre Belloni
Date: Thu May 31 2018 - 05:57:47 EST


The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler.

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ.

Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
---
drivers/rtc/rtc-ds1685.c | 41 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c
index f0f8011dce3d..e6390475380f 100644
--- a/drivers/rtc/rtc-ds1685.c
+++ b/drivers/rtc/rtc-ds1685.c
@@ -2037,6 +2037,22 @@ ds1685_rtc_probe(struct platform_device *pdev)
rtc->write(rtc, RTC_EXT_CTRL_4B,
(rtc->read(rtc, RTC_EXT_CTRL_4B) | RTC_CTRL_4B_KSE));

+ rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(rtc_dev))
+ return PTR_ERR(rtc_dev);
+
+ rtc_dev->ops = &ds1685_rtc_ops;
+
+ /* Maximum periodic rate is 8192Hz (0.122070ms). */
+ rtc_dev->max_user_freq = RTC_MAX_USER_FREQ;
+
+ /* See if the platform doesn't support UIE. */
+ if (pdata->uie_unsupported)
+ rtc_dev->uie_unsupported = 1;
+ rtc->uie_unsupported = pdata->uie_unsupported;
+
+ rtc->dev = rtc_dev;
+
/*
* Fetch the IRQ and setup the interrupt handler.
*
@@ -2069,32 +2085,13 @@ ds1685_rtc_probe(struct platform_device *pdev)
/* Setup complete. */
ds1685_rtc_switch_to_bank0(rtc);

- /* Register the device as an RTC. */
- rtc_dev = rtc_device_register(pdev->name, &pdev->dev,
- &ds1685_rtc_ops, THIS_MODULE);
-
- /* Success? */
- if (IS_ERR(rtc_dev))
- return PTR_ERR(rtc_dev);
-
- /* Maximum periodic rate is 8192Hz (0.122070ms). */
- rtc_dev->max_user_freq = RTC_MAX_USER_FREQ;
-
- /* See if the platform doesn't support UIE. */
- if (pdata->uie_unsupported)
- rtc_dev->uie_unsupported = 1;
- rtc->uie_unsupported = pdata->uie_unsupported;
-
- rtc->dev = rtc_dev;
-
#ifdef CONFIG_SYSFS
ret = ds1685_rtc_sysfs_register(&pdev->dev);
if (ret)
- rtc_device_unregister(rtc->dev);
+ return ret;
#endif

- /* Done! */
- return ret;
+ return rtc_register_device(rtc_dev);
}

/**
@@ -2110,8 +2107,6 @@ ds1685_rtc_remove(struct platform_device *pdev)
ds1685_rtc_sysfs_unregister(&pdev->dev);
#endif

- rtc_device_unregister(rtc->dev);
-
/* Read Ctrl B and clear PIE/AIE/UIE. */
rtc->write(rtc, RTC_CTRL_B,
(rtc->read(rtc, RTC_CTRL_B) &
--
2.17.0