On Thu, Nov 24, 2022 at 03:35:20PM +0100, Matija Glavinic Pecotic wrote:
> set_rtc_noop, get_rtc_noop are used runtime, therefore need init removed.
> Crash was observed on x86 platform where cmos rtc is unused and disabled
> via device tree. Function was triggered from ntp: sync_hw_clock, although
> CONFIG_RTC_SYSTOHC=n, however sync_cmos_clock doesn't honour that.
>
> Workqueue: events_power_efficient sync_hw_clock
> RIP: 0010:set_rtc_noop
> Call Trace:
> update_persistent_clock64
> sync_hw_clock
>
> Fix by dropping __init and making set/get_rtc_noop available runtime.
FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
(I would change prefix to "x86/rtc:" but it's up to you and x86 maintainers)
Note, you need to keep a tag if new version of the patch needs to be sent and
nothing significantly changed there. You may utilize `b4` tool for that (I'm
sure it's available in your distribution) by retrieving patch from the
lore.kernel.org archive.
> Fixes: c311ed6183f4 ("x86/init: Allow DT configured systems to disable RTC at boot time")
> Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@xxxxxxxxx>
> ---
> v3: Update commit message based on Andy's comments (further trim to backtrace, proper tag)
> v2: Update commit message based on Andy's comments
>
> arch/x86/kernel/x86_init.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> index 57353519bc11..0ab707bbefe2 100644
> --- a/arch/x86/kernel/x86_init.c
> +++ b/arch/x86/kernel/x86_init.c
> @@ -32,8 +32,8 @@ static int __init iommu_init_noop(void) { return 0; }
> static void iommu_shutdown_noop(void) { }
> bool __init bool_x86_init_noop(void) { return false; }
> void x86_op_int_noop(int cpu) { }
> -static __init int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
> -static __init void get_rtc_noop(struct timespec64 *now) { }
> +static int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
> +static void get_rtc_noop(struct timespec64 *now) { }
>
> static __initconst const struct of_device_id of_cmos_match[] = {
> { .compatible = "motorola,mc146818" },
> --
> 2.31.0
--
With Best Regards,
Andy Shevchenko
