The probe function is not allowed to fail after registering the RTC because
the following may happen:
CPU0: CPU1:
sys_load_module()
do_init_module()
do_one_initcall()
cmos_do_probe()
rtc_device_register()
__register_chrdev()
cdev->owner = struct module*
open("/dev/rtc0")
rtc_device_unregister()
module_put()
free_module()
module_free(mod->module_core)
/* struct module *module is now
freed */
chrdev_open()
spin_lock(cdev_lock)
cdev_get()
try_module_get()
module_is_live()
/* dereferences already
freed struct module* */
Switch to devm_rtc_allocate_device/rtc_register_device to register the rtc
as late as possible.
Signed-off-by: Alexandre Belloni <alexandre.bell...@bootlin.com>
---
drivers/rtc/rtc-rk808.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/rtc/rtc-rk808.c b/drivers/rtc/rtc-rk808.c
index e40f35d1ced3..739c0d42e835 100644
--- a/drivers/rtc/rtc-rk808.c
+++ b/drivers/rtc/rtc-rk808.c
@@ -405,12 +405,11 @@ static int rk808_rtc_probe(struct platform_device *pdev)
device_init_wakeup(&pdev->dev, 1);
- rk808_rtc->rtc = devm_rtc_device_register(&pdev->dev, "rk808-rtc",
- &rk808_rtc_ops, THIS_MODULE);
- if (IS_ERR(rk808_rtc->rtc)) {
- ret = PTR_ERR(rk808_rtc->rtc);
- return ret;
- }
+ rk808_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(rk808_rtc->rtc))
+ return PTR_ERR(rk808_rtc->rtc);
+
+ rk808_rtc->rtc->ops = &rk808_rtc_ops;
rk808_rtc->irq = platform_get_irq(pdev, 0);
if (rk808_rtc->irq < 0) {
@@ -427,9 +426,10 @@ static int rk808_rtc_probe(struct platform_device *pdev)
if (ret) {
dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
rk808_rtc->irq, ret);
+ return ret;
}
- return ret;
+ return rtc_register_device(rk808_rtc->rtc);
}
static struct platform_driver rk808_rtc_driver = {
--
2.16.1
