[PATCH 2/8] time: Add timekeeping snapshot code capturing system time and counter

[John Stultz]

From: "Christopher S. Hall" 

In the current timekeeping code there isn't any interface to
atomically capture the current relationship between the system counter
and system time. ktime_get_snapshot() returns this triple (counter,
monotonic raw, realtime) in the system_time_snapshot struct.

Cc: Prarit Bhargava 
Cc: Richard Cochran 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Andy Lutomirski 
Cc: kevin.b.stan...@intel.com
Cc: kevin.j.cla...@intel.com
Cc: h...@zytor.com
Cc: jeffrey.t.kirs...@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner 
Signed-off-by: Christopher S. Hall 
[jstultz: Moved structure definitions around to clean things up,
 fixed cycles_t/cycle_t confusion.]
Signed-off-by: John Stultz 
---
 include/linux/timekeeping.h | 18 ++
 kernel/time/timekeeping.c   | 30 ++
 2 files changed, 48 insertions(+)

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index ec89d84..7817591 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -267,6 +267,24 @@ extern void ktime_get_raw_and_real_ts64(struct timespec64 
*ts_raw,
struct timespec64 *ts_real);
 
 /*
+ * struct system_time_snapshot - simultaneous raw/real time capture with
+ * counter value
+ * @cycles:Clocksource counter value to produce the system times
+ * @real:  Realtime system time
+ * @raw:   Monotonic raw system time
+ */
+struct system_time_snapshot {
+   cycle_t cycles;
+   ktime_t real;
+   ktime_t raw;
+};
+
+/*
+ * Simultaneously snapshot realtime and monotonic raw clocks
+ */
+extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
+
+/*
  * Persistent clock related interfaces
  */
 extern int persistent_clock_is_local;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4243d28..89b4695 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -874,6 +874,36 @@ time64_t __ktime_get_real_seconds(void)
return tk->xtime_sec;
 }
 
+/**
+ * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with 
counter
+ * @systime_snapshot:  pointer to struct receiving the system time snapshot
+ */
+void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
+{
+   struct timekeeper *tk = _core.timekeeper;
+   unsigned long seq;
+   ktime_t base_raw;
+   ktime_t base_real;
+   s64 nsec_raw;
+   s64 nsec_real;
+   cycle_t now;
+
+   do {
+   seq = read_seqcount_begin(_core.seq);
+
+   now = tk->tkr_mono.read(tk->tkr_mono.clock);
+   base_real = ktime_add(tk->tkr_mono.base,
+ tk_core.timekeeper.offs_real);
+   base_raw = tk->tkr_raw.base;
+   nsec_real = timekeeping_cycles_to_ns(>tkr_mono, now);
+   nsec_raw  = timekeeping_cycles_to_ns(>tkr_raw, now);
+   } while (read_seqcount_retry(_core.seq, seq));
+
+   systime_snapshot->cycles = now;
+   systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
+   systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
+}
+EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 
 #ifdef CONFIG_NTP_PPS
 
-- 
1.9.1

[PATCH 2/8] time: Add timekeeping snapshot code capturing system time and counter

[John Stultz]

From: "Christopher S. Hall" 

In the current timekeeping code there isn't any interface to
atomically capture the current relationship between the system counter
and system time. ktime_get_snapshot() returns this triple (counter,
monotonic raw, realtime) in the system_time_snapshot struct.

Cc: Prarit Bhargava 
Cc: Richard Cochran 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Andy Lutomirski 
Cc: kevin.b.stan...@intel.com
Cc: kevin.j.cla...@intel.com
Cc: h...@zytor.com
Cc: jeffrey.t.kirs...@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner 
Signed-off-by: Christopher S. Hall 
[jstultz: Moved structure definitions around to clean things up,
 fixed cycles_t/cycle_t confusion.]
Signed-off-by: John Stultz 
---
 include/linux/timekeeping.h | 18 ++
 kernel/time/timekeeping.c   | 30 ++
 2 files changed, 48 insertions(+)

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index ec89d84..7817591 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -267,6 +267,24 @@ extern void ktime_get_raw_and_real_ts64(struct timespec64 
*ts_raw,
struct timespec64 *ts_real);
 
 /*
+ * struct system_time_snapshot - simultaneous raw/real time capture with
+ * counter value
+ * @cycles:Clocksource counter value to produce the system times
+ * @real:  Realtime system time
+ * @raw:   Monotonic raw system time
+ */
+struct system_time_snapshot {
+   cycle_t cycles;
+   ktime_t real;
+   ktime_t raw;
+};
+
+/*
+ * Simultaneously snapshot realtime and monotonic raw clocks
+ */
+extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
+
+/*
  * Persistent clock related interfaces
  */
 extern int persistent_clock_is_local;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4243d28..89b4695 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -874,6 +874,36 @@ time64_t __ktime_get_real_seconds(void)
return tk->xtime_sec;
 }
 
+/**
+ * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with 
counter
+ * @systime_snapshot:  pointer to struct receiving the system time snapshot
+ */
+void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
+{
+   struct timekeeper *tk = _core.timekeeper;
+   unsigned long seq;
+   ktime_t base_raw;
+   ktime_t base_real;
+   s64 nsec_raw;
+   s64 nsec_real;
+   cycle_t now;
+
+   do {
+   seq = read_seqcount_begin(_core.seq);
+
+   now = tk->tkr_mono.read(tk->tkr_mono.clock);
+   base_real = ktime_add(tk->tkr_mono.base,
+ tk_core.timekeeper.offs_real);
+   base_raw = tk->tkr_raw.base;
+   nsec_real = timekeeping_cycles_to_ns(>tkr_mono, now);
+   nsec_raw  = timekeeping_cycles_to_ns(>tkr_raw, now);
+   } while (read_seqcount_retry(_core.seq, seq));
+
+   systime_snapshot->cycles = now;
+   systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
+   systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
+}
+EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 
 #ifdef CONFIG_NTP_PPS
 
-- 
1.9.1