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Subject[tip:timers/urgent] x86/hpet: Fix /dev/rtc breakage caused by RTC cleanup
Commit-ID:  22cc1ca3c5469cf17e149be232817b9223afa5e4
Gitweb: http://git.kernel.org/tip/22cc1ca3c5469cf17e149be232817b9223afa5e4
Author: Arnd Bergmann <arnd@arndb.de>
AuthorDate: Tue, 9 Aug 2016 21:54:53 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 10 Aug 2016 14:37:06 +0200

x86/hpet: Fix /dev/rtc breakage caused by RTC cleanup

Ville Syrjälä reports "The first time I run hwclock after rebooting
I get this:

open("/dev/rtc", O_RDONLY) = 3
ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = 0
select(4, [3], NULL, NULL, {10, 0}) = 0 (Timeout)
ioctl(3, PHN_NOT_OH or RTC_UIE_OFF, 0) = 0
close(3) = 0

On all subsequent runs I get this:

open("/dev/rtc", O_RDONLY) = 3
ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = -1 EINVAL (Invalid argument)
ioctl(3, RTC_RD_TIME, 0x7ffd76b3ae70) = -1 EINVAL (Invalid argument)
close(3) = 0"

This was caused by a stupid typo in a patch that should have been
a simple rename to move around contents of a header file, but
accidentally wrote zeroes into the rtc rather than reading from
it:

463a86304cae ("char/genrtc: x86: remove remnants of asm/rtc.h")

Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rtc-linux@googlegroups.com
Fixes: 463a86304cae ("char/genrtc: x86: remove remnants of asm/rtc.h")
Link: http://lkml.kernel.org/r/20160809195528.1604312-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/hpet.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index ed16e58..c6dfd80 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -1242,7 +1242,7 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
memset(&curr_time, 0, sizeof(struct rtc_time));

if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
- mc146818_set_time(&curr_time);
+ mc146818_get_time(&curr_time);

if (hpet_rtc_flags & RTC_UIE &&
curr_time.tm_sec != hpet_prev_update_sec) {
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