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| author | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2018-02-12 23:47:45 +0100 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2018-03-01 10:49:29 +0100 |
| commit | 53d29e0a3afe0567db9e4360e8523b092eb2d4e4 (patch) | |
| tree | dacc451b5910022aae5fb25acf00a59672f6d19f /drivers/rtc/rtc-cmos.c | |
| parent | rtc: ds1553: make alarms useful (diff) | |
| download | linux-53d29e0a3afe0567db9e4360e8523b092eb2d4e4.tar.xz linux-53d29e0a3afe0567db9e4360e8523b092eb2d4e4.zip | |
rtc: cmos: 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>
Diffstat (limited to 'drivers/rtc/rtc-cmos.c')
| -rw-r--r-- | drivers/rtc/rtc-cmos.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index 9dca53df3584..e6393e784d0c 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -751,8 +751,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq) cmos_rtc.dev = dev; dev_set_drvdata(dev, &cmos_rtc); - cmos_rtc.rtc = rtc_device_register(driver_name, dev, - &cmos_rtc_ops, THIS_MODULE); + cmos_rtc.rtc = devm_rtc_allocate_device(dev); if (IS_ERR(cmos_rtc.rtc)) { retval = PTR_ERR(cmos_rtc.rtc); goto cleanup0; @@ -822,6 +821,11 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq) goto cleanup2; } + cmos_rtc.rtc->ops = &cmos_rtc_ops; + retval = rtc_register_device(cmos_rtc.rtc); + if (retval) + goto cleanup3; + dev_info(dev, "%s%s, %zd bytes nvram%s\n", !is_valid_irq(rtc_irq) ? "no alarms" : cmos_rtc.mon_alrm ? "alarms up to one year" : @@ -833,12 +837,13 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq) return 0; +cleanup3: + sysfs_remove_bin_file(&dev->kobj, &nvram); cleanup2: if (is_valid_irq(rtc_irq)) free_irq(rtc_irq, cmos_rtc.rtc); cleanup1: cmos_rtc.dev = NULL; - rtc_device_unregister(cmos_rtc.rtc); cleanup0: if (RTC_IOMAPPED) release_region(ports->start, resource_size(ports)); @@ -869,7 +874,6 @@ static void cmos_do_remove(struct device *dev) hpet_unregister_irq_handler(cmos_interrupt); } - rtc_device_unregister(cmos->rtc); cmos->rtc = NULL; ports = cmos->iomem; |