diff mbox

[v7,3/8] time: Remove duplicated code in ktime_get_raw_and_real()

Message ID 1455308729-6280-4-git-send-email-christopher.s.hall@intel.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Christopher S. Hall Feb. 12, 2016, 8:25 p.m. UTC 
The code in ktime_get_snapshot() is a superset of the code in
ktime_get_raw_and_real() code. Further, ktime_get_raw_and_real() is
called only by the PPS code, pps_get_ts(). Consolidate the
pps_get_ts() code into a single function calling ktime_get_snapshot()
and eliminate ktime_get_raw_and_real(). A side effect of this is that
the raw and real results of pps_get_ts() correspond to exactly the
same clock cycle. Previously these values represented separate reads
of the system clock.

Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 include/linux/pps_kernel.h | 17 ++++++-----------
 kernel/time/timekeeping.c  | 40 ++--------------------------------------
 2 files changed, 8 insertions(+), 49 deletions(-)

Comments

Richard Cochran Feb. 16, 2016, 7:52 a.m. UTC | #1 
On Fri, Feb 12, 2016 at 12:25:24PM -0800, Christopher S. Hall wrote:
> The code in ktime_get_snapshot() is a superset of the code in
> ktime_get_raw_and_real() code. Further, ktime_get_raw_and_real() is
> called only by the PPS code, pps_get_ts(). Consolidate the
> pps_get_ts() code into a single function calling ktime_get_snapshot()
> and eliminate ktime_get_raw_and_real(). A side effect of this is that
> the raw and real results of pps_get_ts() correspond to exactly the
> same clock cycle. Previously these values represented separate reads
> of the system clock.

Nice improvement.

> @@ -888,6 +888,8 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
>  	s64 nsec_real;
>  	cycle_t now;
>  
> +	WARN_ON(timekeeping_suspended);
...
> -	WARN_ON_ONCE(timekeeping_suspended);

Is this change intentional?

Thanks,
Richard
Christopher S. Hall Feb. 16, 2016, 6:23 p.m. UTC | #2 
On Mon, 15 Feb 2016 23:52:10 -0800, Richard Cochran  
<richardcochran@gmail.com> wrote:
>> @@ -888,6 +888,8 @@ void ktime_get_snapshot(struct system_time_snapshot  
>> *systime_snapshot)
>>  	s64 nsec_real;
>>  	cycle_t now;
>>
>> +	WARN_ON(timekeeping_suspended);
> ...
>> -	WARN_ON_ONCE(timekeeping_suspended);
>
> Is this change intentional?

Yes it is. The code I replaced in pps_kernel.h (pps_get_ts()) has two call  
paths depending on whether CONFIG_NTP_PPS is set. On one call path  
(realtime only, config unset) WARN_ON(), from getnstimeofday64, is used,  
on the other WARN_ON_ONCE(), from ktime_get_raw_and_real_ts64(), is used.  
I opted for the greater verbosity of the two when I combined the code.

Is WARN_ON_ONCE() better here?

Thanks,
Chris
diff mbox

Patch

diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index 54bf148..35ac903 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -111,22 +111,17 @@  static inline void timespec_to_pps_ktime(struct pps_ktime *kt,
 	kt->nsec = ts.tv_nsec;
 }
 
-#ifdef CONFIG_NTP_PPS
-
 static inline void pps_get_ts(struct pps_event_time *ts)
 {
-	ktime_get_raw_and_real_ts64(&ts->ts_raw, &ts->ts_real);
-}
+	struct system_time_snapshot snap;
 
-#else /* CONFIG_NTP_PPS */
-
-static inline void pps_get_ts(struct pps_event_time *ts)
-{
-	ktime_get_real_ts64(&ts->ts_real);
+	ktime_get_snapshot(&snap);
+	ts->ts_real = ktime_to_timespec64(snap.real);
+#ifdef CONFIG_NTP_PPS
+	ts->ts_raw = ktime_to_timespec64(snap.raw);
+#endif
 }
 
-#endif /* CONFIG_NTP_PPS */
-
 /* Subtract known time delay from PPS event time(s) */
 static inline void pps_sub_ts(struct pps_event_time *ts, struct timespec64 delta)
 {
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 89b4695..f1a1c97 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -888,6 +888,8 @@  void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 	s64 nsec_real;
 	cycle_t now;
 
+	WARN_ON(timekeeping_suspended);
+
 	do {
 		seq = read_seqcount_begin(&tk_core.seq);
 
@@ -905,44 +907,6 @@  void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 }
 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 
-#ifdef CONFIG_NTP_PPS
-
-/**
- * ktime_get_raw_and_real_ts64 - get day and raw monotonic time in timespec format
- * @ts_raw:	pointer to the timespec to be set to raw monotonic time
- * @ts_real:	pointer to the timespec to be set to the time of day
- *
- * This function reads both the time of day and raw monotonic time at the
- * same time atomically and stores the resulting timestamps in timespec
- * format.
- */
-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;
-
-	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));
-
-	timespec64_add_ns(ts_raw, nsecs_raw);
-	timespec64_add_ns(ts_real, nsecs_real);
-}
-EXPORT_SYMBOL(ktime_get_raw_and_real_ts64);
-
-#endif /* CONFIG_NTP_PPS */
-
 /**
  * do_gettimeofday - Returns the time of day in a timeval
  * @tv:		pointer to the timeval to be set