[PATCH v4 1/2] sched: Add sched_clock_register_new()

[Paul Cercueil]

The sched_clock_register_new() behaves like sched_clock_register() but
takes an extra parameter which is passed to the read callback.

Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---

Notes:
    v4: New patch

 include/linux/sched_clock.h |  2 ++
 kernel/time/sched_clock.c   | 36 +++++++++++++++++++++++++-----------
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h
index 0bb04a96a6d4..15509487fd16 100644
--- a/include/linux/sched_clock.h
+++ b/include/linux/sched_clock.h
@@ -10,6 +10,8 @@ extern void generic_sched_clock_init(void);
 
 extern void sched_clock_register(u64 (*read)(void), int bits,
 				 unsigned long rate);
+extern void sched_clock_register_new(u64 (*read)(void *), int bits,
+				     unsigned long rate, void *data);
 #else
 static inline void generic_sched_clock_init(void) { }
 
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index e4332e3e2d56..9ba61814ea48 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -27,6 +27,7 @@
  * @sched_clock_mask:   Bitmask for two's complement subtraction of non 64bit
  *			clocks.
  * @read_sched_clock:	Current clock source (or dummy source when suspended).
+ * @data:		Callback data for the current clock source.
  * @mult:		Multipler for scaled math conversion.
  * @shift:		Shift value for scaled math conversion.
  *
@@ -39,7 +40,8 @@ struct clock_read_data {
 	u64 epoch_ns;
 	u64 epoch_cyc;
 	u64 sched_clock_mask;
-	u64 (*read_sched_clock)(void);
+	u64 (*read_sched_clock)(void *);
+	void *data;
 	u32 mult;
 	u32 shift;
 };
@@ -53,6 +55,7 @@ struct clock_read_data {
  * @read_data:		Data required to read from sched_clock.
  * @wrap_kt:		Duration for which clock can run before wrapping.
  * @rate:		Tick rate of the registered clock.
+ * @data:		Callback data for the registered clock read function.
  * @actual_read_sched_clock: Registered hardware level clock read function.
  *
  * The ordering of this structure has been chosen to optimize cache
@@ -65,7 +68,8 @@ struct clock_data {
 	ktime_t			wrap_kt;
 	unsigned long		rate;
 
-	u64 (*actual_read_sched_clock)(void);
+	void			*data;
+	u64 (*actual_read_sched_clock)(void *);
 };
 
 static struct hrtimer sched_clock_timer;
@@ -73,7 +77,7 @@ static int irqtime = -1;
 
 core_param(irqtime, irqtime, int, 0400);
 
-static u64 notrace jiffy_sched_clock_read(void)
+static u64 notrace jiffy_sched_clock_read(void *d)
 {
 	/*
 	 * We don't need to use get_jiffies_64 on 32-bit arches here
@@ -103,7 +107,7 @@ unsigned long long notrace sched_clock(void)
 		seq = raw_read_seqcount(&cd.seq);
 		rd = cd.read_data + (seq & 1);
 
-		cyc = (rd->read_sched_clock() - rd->epoch_cyc) &
+		cyc = (rd->read_sched_clock(rd->data) - rd->epoch_cyc) &
 		      rd->sched_clock_mask;
 		res = rd->epoch_ns + cyc_to_ns(cyc, rd->mult, rd->shift);
 	} while (read_seqcount_retry(&cd.seq, seq));
@@ -147,7 +151,7 @@ static void update_sched_clock(void)
 
 	rd = cd.read_data[0];
 
-	cyc = cd.actual_read_sched_clock();
+	cyc = cd.actual_read_sched_clock(cd.data);
 	ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift);
 
 	rd.epoch_ns = ns;
@@ -165,7 +169,8 @@ static enum hrtimer_restart sched_clock_poll(struct hrtimer *hrt)
 }
 
 void __init
-sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
+sched_clock_register_new(u64 (*read)(void *), int bits,
+			 unsigned long rate, void *data)
 {
 	u64 res, wrap, new_mask, new_epoch, cyc, ns;
 	u32 new_mult, new_shift;
@@ -192,12 +197,14 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
 	rd = cd.read_data[0];
 
 	/* Update epoch for new counter and update 'epoch_ns' from old counter*/
-	new_epoch = read();
-	cyc = cd.actual_read_sched_clock();
+	new_epoch = read(data);
+	cyc = cd.actual_read_sched_clock(cd.data);
 	ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift);
 	cd.actual_read_sched_clock = read;
+	cd.data = data;
 
 	rd.read_sched_clock	= read;
+	rd.data			= data;
 	rd.sched_clock_mask	= new_mask;
 	rd.mult			= new_mult;
 	rd.shift		= new_shift;
@@ -239,6 +246,12 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
 	pr_debug("Registered %pS as sched_clock source\n", read);
 }
 
+void __init
+sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
+{
+	sched_clock_register_new((u64 (*)(void *))read, bits, rate, NULL);
+}
+
 void __init generic_sched_clock_init(void)
 {
 	/*
@@ -246,7 +259,8 @@ void __init generic_sched_clock_init(void)
 	 * make it the final one one.
 	 */
 	if (cd.actual_read_sched_clock == jiffy_sched_clock_read)
-		sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ);
+		sched_clock_register_new(jiffy_sched_clock_read,
+					 BITS_PER_LONG, HZ, NULL);
 
 	update_sched_clock();
 
@@ -270,7 +284,7 @@ void __init generic_sched_clock_init(void)
  * at the end of the critical section to be sure we observe the
  * correct copy of 'epoch_cyc'.
  */
-static u64 notrace suspended_sched_clock_read(void)
+static u64 notrace suspended_sched_clock_read(void *d)
 {
 	unsigned int seq = raw_read_seqcount(&cd.seq);
 
@@ -292,7 +306,7 @@ void sched_clock_resume(void)
 {
 	struct clock_read_data *rd = &cd.read_data[0];
 
-	rd->epoch_cyc = cd.actual_read_sched_clock();
+	rd->epoch_cyc = cd.actual_read_sched_clock(cd.data);
 	hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
 	rd->read_sched_clock = cd.actual_read_sched_clock;
 }
-- 
2.24.1