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Subject[PATCH v2 1/2] clocksource: track usage
Date
Track whether the clocksource is enabled or disabled.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
include/linux/clocksource.h | 4 ++++
kernel/time/clocksource.c | 30 ++++++++++++++++++++++++++++++
kernel/time/timekeeping.c | 8 +++-----
3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index abcafaa20b86..7735902fc5f6 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -210,6 +210,8 @@ struct clocksource {
#define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
#define CLOCK_SOURCE_RESELECT 0x100

+#define CLOCK_SOURCE_USED 0x200
+
/* simplify initialization of mask field */
#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)

@@ -282,6 +284,8 @@ static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)

extern int clocksource_register(struct clocksource*);
extern int clocksource_unregister(struct clocksource*);
+extern int clocksource_enable(struct clocksource *);
+extern void clocksource_disable(struct clocksource *);
extern void clocksource_touch_watchdog(void);
extern struct clocksource* clocksource_get_next(void);
extern void clocksource_change_rating(struct clocksource *cs, int rating);
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index b79f39bda7e1..03cfc5a08e3b 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -889,6 +889,36 @@ int clocksource_unregister(struct clocksource *cs)
}
EXPORT_SYMBOL(clocksource_unregister);

+/**
+ * clocksource_enable - enable a registered clocksource
+ * @cs: clocksource to enable
+ */
+int clocksource_enable(struct clocksource *cs)
+{
+ int ret = 0;
+
+ if (cs->enable)
+ ret = cs->enable(cs);
+
+ if (!ret)
+ cs->flags |= CLOCK_SOURCE_USED;
+
+ return ret;
+}
+EXPORT_SYMBOL(clocksource_enable);
+
+/**
+ * clocksource_disable - disable a registered clocksource
+ * @cs: clocksource to disable
+ */
+void clocksource_disable(struct clocksource *cs)
+{
+ cs->flags &= ~CLOCK_SOURCE_USED;
+ if (cs->disable)
+ cs->disable(cs);
+}
+EXPORT_SYMBOL(clocksource_disable);
+
#ifdef CONFIG_SYSFS
/**
* sysfs_show_current_clocksources - sysfs interface for current clocksource
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6a931852082f..82da6b94382c 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -915,11 +915,10 @@ static int change_clocksource(void *data)
* for built-in code (owner == NULL) as well.
*/
if (try_module_get(new->owner)) {
- if (!new->enable || new->enable(new) == 0) {
+ if (clocksource_enable(new) == 0) {
old = tk->tkr.clock;
tk_setup_internals(tk, new);
- if (old->disable)
- old->disable(old);
+ clocksource_disable(old);
module_put(old->owner);
} else {
module_put(new->owner);
@@ -1080,8 +1079,7 @@ void __init timekeeping_init(void)
ntp_init();

clock = clocksource_default_clock();
- if (clock->enable)
- clock->enable(clock);
+ clocksource_enable(clock);
tk_setup_internals(tk, clock);

tk_set_xtime(tk, &now);
--
2.1.0


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