linux-kernel - [PATCH 6/8] timekeeping: Hold timekeepering locks in do

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Date:	Mon, 25 Mar 2013 13:08:16 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Richard Cochran <richardcochran@...il.com>,
	Prarit Bhargava <prarit@...hat.com>
Subject: [PATCH 6/8] timekeeping: Hold timekeepering locks in do_adjtimex and hardpps

In moving the NTP state to be protected by the timekeeping locks,
be sure to acquire the timekeeping locks prior to calling
ntp functions.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Richard Cochran <richardcochran@...il.com>
Cc: Prarit Bhargava <prarit@...hat.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 kernel/time/timekeeping.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e44915c..d10bd73 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -787,10 +787,10 @@ void __init timekeeping_init(void)
 		boot.tv_nsec = 0;
 	}
 
-	ntp_init();
-
 	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 	write_seqcount_begin(&timekeeper_seq);
+	ntp_init();
+
 	clock = clocksource_default_clock();
 	if (clock->enable)
 		clock->enable(clock);
@@ -1618,6 +1618,7 @@ EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
  */
 int do_adjtimex(struct timex *txc)
 {
+	unsigned long flags;
 	struct timespec ts;
 	s32 tai, orig_tai;
 	int ret;
@@ -1641,8 +1642,14 @@ int do_adjtimex(struct timex *txc)
 	getnstimeofday(&ts);
 	orig_tai = tai = timekeeping_get_tai_offset();
 
+	raw_spin_lock_irqsave(&timekeeper_lock, flags);
+	write_seqcount_begin(&timekeeper_seq);
+
 	ret = __do_adjtimex(txc, &ts, &tai);
 
+	write_seqcount_end(&timekeeper_seq);
+	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+
 	if (tai != orig_tai)
 		timekeeping_set_tai_offset(tai);
 
@@ -1655,7 +1662,15 @@ int do_adjtimex(struct timex *txc)
  */
 void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
 {
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&timekeeper_lock, flags);
+	write_seqcount_begin(&timekeeper_seq);
+
 	__hardpps(phase_ts, raw_ts);
+
+	write_seqcount_end(&timekeeper_seq);
+	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 }
 EXPORT_SYMBOL(hardpps);
 #endif
-- 
1.7.10.4

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