linux-kernel - [RFC v5 4/6] Remove duplicate code from ktime_get_raw_and

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Message-Id: <1451911523-8534-5-git-send-email-christopher.s.hall@intel.com>
Date:	Mon,  4 Jan 2016 04:45:21 -0800
From:	"Christopher S. Hall" <christopher.s.hall@...el.com>
To:	tglx@...utronix.de, richardcochran@...il.com, mingo@...hat.com,
	john.stultz@...aro.org, hpa@...or.com, jeffrey.t.kirsher@...el.com
Cc:	"Christopher S. Hall" <christopher.s.hall@...el.com>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	kevin.b.stanton@...el.com
Subject: [RFC v5 4/6] Remove duplicate code from ktime_get_raw_and_real code

The code in ktime_get_snapshot() is a superset of the code in
ktime_get_raw_and_real() code. Changes the latter to call the former. A
side effect of this is that ktime_get_raw_and_real() returns two clock
times corresponding to the *exact* same clock tick. Previously, this
code read the underlying counter twice.

Signed-off-by: Christopher S. Hall <christopher.s.hall@...el.com>
---
 kernel/time/timekeeping.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5a7f784..a0f096c 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -910,26 +910,14 @@ EXPORT_SYMBOL_GPL(ktime_get_snapshot);
  */
 void ktime_get_raw_and_real_ts64(struct timespec64 *ts_raw, struct timespec64 *ts_real)
 {
-	struct timekeeper *tk = &tk_core.timekeeper;
-	unsigned long seq;
-	s64 nsecs_raw, nsecs_real;
+	struct system_time_snapshot snap;
 
 	WARN_ON_ONCE(timekeeping_suspended);
 
-	do {
-		seq = read_seqcount_begin(&tk_core.seq);
-
-		*ts_raw = tk->raw_time;
-		ts_real->tv_sec = tk->xtime_sec;
-		ts_real->tv_nsec = 0;
-
-		nsecs_raw  = timekeeping_get_ns(&tk->tkr_raw);
-		nsecs_real = timekeeping_get_ns(&tk->tkr_mono);
-
-	} while (read_seqcount_retry(&tk_core.seq, seq));
+	ktime_get_snapshot(&snap);
 
-	timespec64_add_ns(ts_raw, nsecs_raw);
-	timespec64_add_ns(ts_real, nsecs_real);
+	*ts_raw = ktime_to_timespec64(snap.raw);
+	*ts_real = ktime_to_timespec64(snap.real);
 }
 EXPORT_SYMBOL(ktime_get_raw_and_real_ts64);
 
-- 
2.1.4

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