linux-kernel - [PATCH v2] NTP: Let update_persistent

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Date:	Thu, 29 May 2008 19:19:04 +0100 (BST)
From:	"Maciej W. Rozycki" <macro@...ux-mips.org>
To:	Roman Zippel <zippel@...ux-m68k.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>
cc:	Alessandro Zummo <a.zummo@...ertech.it>,
	Rik van Riel <riel@...hat.com>,
	David Brownell <david-b@...bell.net>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] NTP: Let update_persistent_clock() sleep

 This is a change that makes the 11-minute RTC update be run in the
process context.  This is so that update_persistent_clock() can sleep,
which may be required for certain types of RTC hardware -- most notably
I2C devices.

Signed-off-by: Maciej W. Rozycki <macro@...ux-mips.org>
---
Hello,

 This is the second version of the change -- the use of
schedule_delayed_work() makes it simpler and lets the timer be removed
altogether.  It obsoletes ntp-make-the-rtc-sync-mode-11-minute-again.patch
too (Andrew, please withdraw it from your tree), which is a good sign.

 Tested like the original with a Broadcom SWARM board and its M41T81 RTC
chip using the rtc-m41t80.c driver through the set of changes published 
earlier.

  Maciej

patch-2.6.26-rc1-20080505-sync-cmos-work-3
diff -up --recursive --new-file linux-2.6.26-rc1-20080505.macro/kernel/time/ntp.c linux-2.6.26-rc1-20080505/kernel/time/ntp.c
--- linux-2.6.26-rc1-20080505.macro/kernel/time/ntp.c	2008-05-05 02:56:03.000000000 +0000
+++ linux-2.6.26-rc1-20080505/kernel/time/ntp.c	2008-05-29 17:49:04.000000000 +0000
@@ -10,13 +10,13 @@
 
 #include <linux/mm.h>
 #include <linux/time.h>
-#include <linux/timer.h>
 #include <linux/timex.h>
 #include <linux/jiffies.h>
 #include <linux/hrtimer.h>
 #include <linux/capability.h>
 #include <linux/math64.h>
 #include <linux/clocksource.h>
+#include <linux/workqueue.h>
 #include <asm/timex.h>
 
 /*
@@ -218,11 +218,11 @@ void second_overflow(void)
 /* Disable the cmos update - used by virtualization and embedded */
 int no_sync_cmos_clock  __read_mostly;
 
-static void sync_cmos_clock(unsigned long dummy);
+static void sync_cmos_clock(struct work_struct *work);
 
-static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
+static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
 
-static void sync_cmos_clock(unsigned long dummy)
+static void sync_cmos_clock(struct work_struct *work)
 {
 	struct timespec now, next;
 	int fail = 1;
@@ -258,13 +258,13 @@ static void sync_cmos_clock(unsigned lon
 		next.tv_sec++;
 		next.tv_nsec -= NSEC_PER_SEC;
 	}
-	mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next));
+	schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next));
 }
 
 static void notify_cmos_timer(void)
 {
 	if (!no_sync_cmos_clock)
-		mod_timer(&sync_cmos_timer, jiffies + 1);
+		schedule_delayed_work(&sync_cmos_work, 0);
 }
 
 #else
--
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