diff options
| author | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2018-02-12 23:47:49 +0100 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2018-03-01 10:49:30 +0100 |
| commit | bcdd559268039d8340d38fa58668393596e29fdc (patch) | |
| tree | de9e645878a31aafa2646c1692454155c53d2153 | |
| parent | 87c78d9512cb85c286de5a8941eaeda8ca6f7bac (diff) | |
rtc: rp5c01: fix possible race condition
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.belloni@bootlin.com>
| -rw-r--r-- | drivers/rtc/rtc-rp5c01.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-rp5c01.c b/drivers/rtc/rtc-rp5c01.c index 026035373ae6..38a12435b5a0 100644 --- a/drivers/rtc/rtc-rp5c01.c +++ b/drivers/rtc/rtc-rp5c01.c @@ -249,16 +249,24 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev) platform_set_drvdata(dev, priv); - rtc = devm_rtc_device_register(&dev->dev, "rtc-rp5c01", &rp5c01_rtc_ops, - THIS_MODULE); + rtc = devm_rtc_allocate_device(&dev->dev); if (IS_ERR(rtc)) return PTR_ERR(rtc); + + rtc->ops = &rp5c01_rtc_ops; + priv->rtc = rtc; error = sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr); if (error) return error; + error = rtc_register_device(rtc); + if (error) { + sysfs_remove_bin_file(&dev->dev.kobj, &priv->nvram_attr); + return error; + } + return 0; } |