Fix a commit 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET") `rtc-cmos' regression causing a link error:

drivers/rtc/rtc-cmos.o: In function `cmos_platform_probe': rtc-cmos.c:(.init.text+0x33c): undefined reference to `hpet_rtc_interrupt' rtc-cmos.c:(.init.text+0x3f4): undefined reference to `hpet_rtc_interrupt'

with non-ACPI platforms using this driver. The cause is the change of the condition guarding the use of `hpet_rtc_interrupt'.

Previously it was a call to `is_hpet_enabled'. That function is static inline and has a hardcoded 0 result for non-ACPI platforms, which imply !HPET_EMULATE_RTC. Consequently the compiler optimized the whole block away including the reference to `hpet_rtc_interrupt', which never made it to the link stage.

Now the guarding condition is a call to `use_hpet_alarm', which is not static inline and therefore the compiler may not be able to prove that it actually always returns 0 for non-ACPI platforms. Consequently the build breaks with an unsatisfied reference, because `hpet_rtc_interrupt' is nowhere defined at link time.

Fix the problem by marking `use_hpet_alarm' inline. As the `inline' keyword serves as an optimization hint rather than a requirement the compiler is still free to choose whether inlining will be beneficial or not for ACPI platforms.

Signed-off-by: Maciej W. Rozycki macro@linux-mips.org Fixes: 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET") Cc: stable@vger.kernel.org # 4.18+ --- drivers/rtc/rtc-cmos.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

linux-rtc-cmos-use-hpet-alarm-inline.diff Index: linux-20180812-4maxp64/drivers/rtc/rtc-cmos.c =================================================================== --- linux-20180812-4maxp64.orig/drivers/rtc/rtc-cmos.c +++ linux-20180812-4maxp64/drivers/rtc/rtc-cmos.c @@ -167,7 +167,7 @@ static inline int hpet_unregister_irq_ha #endif

/* Don't use HPET for RTC Alarm event if ACPI Fixed event is used */ -static int use_hpet_alarm(void) +static inline int use_hpet_alarm(void) { return is_hpet_enabled() && !use_acpi_alarm; }