arch/x86/include/asm/mc146818rtc.h:44:2: error: implicit declaration of function 'this_cpu_read'

Hi Arnd,

FYI, kernel build failed on

commit: 72e2c3166db31bbb25654be3985ea662fa141d8e warnings in include/linux/mc146818rtc.h
config: i386-allmodconfig

All error/warnings:

arch/x86/include/asm/mc146818rtc.h:44:17: sparse: undefined identifier 'this_cpu_read' arch/x86/include/asm/mc146818rtc.h:44:17: sparse: not a function <noident> In file included from include/linux/mc146818rtc.h:15:0,

                 from arch/x86/kernel/rtc.c:5:

arch/x86/include/asm/mc146818rtc.h: In function 'lock_cmos':
arch/x86/include/asm/mc146818rtc.h:44:2: error: implicit declaration of function 'this_cpu_read' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
--
In file included from include/linux/mc146818rtc.h:15:0,
from drivers/char/mwave/smapi.c:50:
arch/x86/include/asm/mc146818rtc.h: In function 'lock_cmos':
arch/x86/include/asm/mc146818rtc.h:44:2: error: implicit declaration of function 'this_cpu_read' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors

sparse static analyze warnings:

? arch/x86/include/asm/mc146818rtc.h:44:17: sparse: undefined identifier 'this_cpu_read' ? arch/x86/include/asm/mc146818rtc.h:44:17: sparse: not a function <noident>

vim +44 arch/x86/include/asm/mc146818rtc.h

6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  41) static inline void lock_cmos(unsigned char reg)
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  42) {
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  43) 	unsigned long new;
933a4415 include/asm-x86/mc146818rtc.h (Joe Perches     2008-03-23 @44) 	new = ((smp_processor_id() + 1) << 8) | reg;
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  45) 	for (;;) {
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  46) 		if (cmos_lock) {
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  47) 			cpu_relax();
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  48) 			continue;
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  49) 		}
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  50) 		if (__cmpxchg(&cmos_lock, 0, new, sizeof(cmos_lock)) = 0)
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  51) 			return;
6ce60b07 include/asm-x86/mc146818rtc.h (Thomas Gleixner 2008-01-30  52) 	}

---
0-DAY kernel build testing backend Open Source Technology Centre
Fengguang Wu, Yuanhan Liu Intel Corporation

Thanks for the report. I've looked at the situation again and come up with a better fix now to replace my original patch:

commit 6f2bcb731779d5709558fa044a4ac67a384102e1

Author: Arnd Bergmann <[email protected]>
Date:   Wed Oct 3 13:13:27 2012 +0000

ARM: footbridge: remove RTC_IRQ definition

Since commit bd8abc9a32c "ARM: mc146818rtc: remove unnecessary include of mach/irqs.h", building footbridge_defconfig results in this warning:

In file included from include/linux/mc146818rtc.h:16:0,
from arch/arm/mach-footbridge/isa-rtc.c:21:
arch/arm/include/asm/mc146818rtc.h:10:0: warning: "RTC_IRQ" redefined [enabled by default] arch/arm/mach-footbridge/include/mach/irqs.h:93:0: note: this is the location of the previous definition

The above commit was intentionally made to catch errors like this, where code relies on the RTC_IRQ definition. The only driver using it is the legacy PC-style drivers/char/rtc.c driver. However, the ARM architecture has been using the RTC_LIB framework since at least 2006, and that doesn't use it.

index 400551e..61c714c 100644
@@ -89,8 +89,6 @@
 #define IRQ_NETWINDER_VGA	_ISA_IRQ(11)
 #define IRQ_NETWINDER_SOUND	_ISA_IRQ(12)
 
-#undef RTC_IRQ
-#define RTC_IRQ		IRQ_ISA_RTC_ALARM
 #define I8042_KBD_IRQ	IRQ_ISA_KEYBOARD
 #define I8042_AUX_IRQ	(machine_is_netwinder() ? IRQ_NETWINDER_PS2MOUSE : IRQ_ISA_PS2MOUSE)
 #define IRQ_FLOPPYDISK	IRQ_ISA_FLOPPY