linux-kernel - [git pull] timer fixes

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Message-ID: <20080825175226.GA9892@elte.hu>
Date:	Mon, 25 Aug 2008 19:52:26 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [git pull] timer fixes

Linus,

Please pull the latest timers-fixes-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git timers-fixes-for-linus

Thanks,

	Ingo

------------------>
Ingo Molnar (1):
      rtc: fix deadlock


 include/asm-generic/rtc.h |   12 ++++--------
 1 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/include/asm-generic/rtc.h b/include/asm-generic/rtc.h
index be4af00..71ef3f0 100644
--- a/include/asm-generic/rtc.h
+++ b/include/asm-generic/rtc.h
@@ -15,6 +15,7 @@
 #include <linux/mc146818rtc.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
+#include <linux/delay.h>
 
 #define RTC_PIE 0x40		/* periodic interrupt enable */
 #define RTC_AIE 0x20		/* alarm interrupt enable */
@@ -43,7 +44,6 @@ static inline unsigned char rtc_is_updating(void)
 
 static inline unsigned int get_rtc_time(struct rtc_time *time)
 {
-	unsigned long uip_watchdog = jiffies;
 	unsigned char ctrl;
 	unsigned long flags;
 
@@ -53,19 +53,15 @@ static inline unsigned int get_rtc_time(struct rtc_time *time)
 
 	/*
 	 * read RTC once any update in progress is done. The update
-	 * can take just over 2ms. We wait 10 to 20ms. There is no need to
+	 * can take just over 2ms. We wait 20ms. There is no need to
 	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
 	 * If you need to know *exactly* when a second has started, enable
 	 * periodic update complete interrupts, (via ioctl) and then 
 	 * immediately read /dev/rtc which will block until you get the IRQ.
 	 * Once the read clears, read the RTC time (again via ioctl). Easy.
 	 */
-
-	if (rtc_is_updating() != 0)
-		while (jiffies - uip_watchdog < 2*HZ/100) {
-			barrier();
-			cpu_relax();
-		}
+	if (rtc_is_updating())
+		mdelay(20);
 
 	/*
 	 * Only the values that we read from the RTC are set. We leave
--
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