linux-kernel - [tip:timers/urgent] x86/hpet: Fix /dev/rtc breakage caused by RTC cleanup

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Date:	Wed, 10 Aug 2016 11:08:17 -0700
From:	tip-bot for Arnd Bergmann <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, geert@...ux-m68k.org, a.zummo@...ertech.it,
	torvalds@...ux-foundation.org, ville.syrjala@...ux.intel.com,
	hpa@...or.com, alexandre.belloni@...e-electrons.com,
	jarkko.nikula@...ux.intel.com, linux-kernel@...r.kernel.org,
	arnd@...db.de, tglx@...utronix.de, bp@...e.de, peterz@...radead.org
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@...db.de>
AuthorDate: Tue, 9 Aug 2016 21:54:53 +0200
Committer:  Ingo Molnar <mingo@...nel.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@...ux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Cc: Alessandro Zummo <a.zummo@...ertech.it>
Cc: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: rtc-linux@...glegroups.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@...nel.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) {