[2/6] timekeeping: Pass readout base to update_fast_timekeeper()

Commit Message

Rafael J. Wysocki Feb. 11, 2015, 4:01 a.m. UTC

From: Rafael J. Wysocki <[e-mail]>

Modify update_fast_timekeeper() to take a struct tk_read_base
pointer as its argument (instead of a struct timekeeper pointer)
and update its kerneldoc comment to reflect that.

That will allow a struct tk_read_base that is not part of a
struct timekeeper to be passed to it in the next patch.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
---
 kernel/time/timekeeping.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)


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Comments

John Stultz Feb. 13, 2015, 12:29 a.m. UTC | #1

On Wed, Feb 11, 2015 at 12:01 PM, Rafael J. Wysocki <[e-mail]> wrote:
> From: Rafael J. Wysocki <[e-mail]>
>
> Modify update_fast_timekeeper() to take a struct tk_read_base
> pointer as its argument (instead of a struct timekeeper pointer)
> and update its kerneldoc comment to reflect that.
>
> That will allow a struct tk_read_base that is not part of a
> struct timekeeper to be passed to it in the next patch.
>
> Signed-off-by: Rafael J. Wysocki <[e-mail]>

Thomas was really behind the update_fast_timekeeper design so I'm not
sure I can critique if this fits in the larger vision here, but I
don't see anything wrong and its not breaking in any of my tests,
so...

Acked-by: John Stultz <[e-mail]>

thanks
-john
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Patch

Index: linux-pm/kernel/time/timekeeping.c
===================================================================
--- linux-pm.orig/kernel/time/timekeeping.c
+++ linux-pm/kernel/time/timekeeping.c
@@ -230,9 +230,7 @@  static inline s64 timekeeping_get_ns_raw
 
 /**
  * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
- * @tk:		The timekeeper from which we take the update
- * @tkf:	The fast timekeeper to update
- * @tbase:	The time base for the fast timekeeper (mono/raw)
+ * @tkr: Timekeeping readout base from which we take the update
  *
  * We want to use this from any context including NMI and tracing /
  * instrumenting the timekeeping code itself.
@@ -244,11 +242,11 @@  static inline s64 timekeeping_get_ns_raw
  * smp_wmb();	<- Ensure that the last base[1] update is visible
  * tkf->seq++;
  * smp_wmb();	<- Ensure that the seqcount update is visible
- * update(tkf->base[0], tk);
+ * update(tkf->base[0], tkr);
  * smp_wmb();	<- Ensure that the base[0] update is visible
  * tkf->seq++;
  * smp_wmb();	<- Ensure that the seqcount update is visible
- * update(tkf->base[1], tk);
+ * update(tkf->base[1], tkr);
  *
  * The reader side does:
  *
@@ -269,7 +267,7 @@  static inline s64 timekeeping_get_ns_raw
  * slightly wrong timestamp (a few nanoseconds). See
  * @ktime_get_mono_fast_ns.
  */
-static void update_fast_timekeeper(struct timekeeper *tk)
+static void update_fast_timekeeper(struct tk_read_base *tkr)
 {
 	struct tk_read_base *base = tk_fast_mono.base;
 
@@ -277,7 +275,7 @@  static void update_fast_timekeeper(struc
 	raw_write_seqcount_latch(&tk_fast_mono.seq);
 
 	/* Update base[0] */
-	memcpy(base, &tk->tkr, sizeof(*base));
+	memcpy(base, tkr, sizeof(*base));
 
 	/* Force readers back to base[0] */
 	raw_write_seqcount_latch(&tk_fast_mono.seq);
@@ -462,7 +460,7 @@  static void timekeeping_update(struct ti
 		memcpy(&shadow_timekeeper, &tk_core.timekeeper,
 		       sizeof(tk_core.timekeeper));
 
-	update_fast_timekeeper(tk);
+	update_fast_timekeeper(&tk->tkr);
 }
 
 /**