On 04/25/2013 01:31 PM, Thomas Gleixner wrote:
Preparatory patch for clocksource unbind support.
Modify clocksource_select, so it skips the current clocksource on
request and tries to find a fallback clocksource. Convert all existing
users. No functional change.
Signed-off-by: Thomas Gleixner<t...@linutronix.de>
---
kernel/time/clocksource.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)
Index: tip/kernel/time/clocksource.c
===================================================================
--- tip.orig/kernel/time/clocksource.c
+++ tip/kernel/time/clocksource.c
@@ -553,7 +553,7 @@ static u64 clocksource_max_deferment(str
#ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
-static struct clocksource *clocksource_find_best(bool oneshot)
+static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur)
{
struct clocksource *cs;
@@ -566,6 +566,8 @@ static struct clocksource *clocksource_f
* the best rating.
*/
list_for_each_entry(cs, &clocksource_list, list) {
+ if (skipcur && cs == curr_clocksource)
+ continue;
if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES))
continue;
return cs;
@@ -581,18 +583,20 @@ static struct clocksource *clocksource_f
* Select the clocksource with the best rating, or the clocksource,
* which is selected by userspace override.
*/
-static void clocksource_select(void)
+static void clocksource_select(bool skipcur)
{
bool oneshot = tick_oneshot_mode_active();
struct clocksource *best, *cs;
/* Find the best suitable clocksource */
- best = clocksource_find_best(oneshot);
+ best = clocksource_find_best(oneshot, skipcur);
if (!best)
return;
/* Check for the override clocksource. */
list_for_each_entry(cs, &clocksource_list, list) {
+ if (skipcur && cs == curr_clocksource)
+ continue;
if (strcmp(cs->name, override_name) != 0)
continue;
/*
@@ -620,7 +624,7 @@ static void clocksource_select(void)
#else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */
-static inline void clocksource_select(void) { }
+static inline void clocksource_select(bool skipcur) { }
#endif
Not a major objection, but I sort of don't like the bool flag arguments
to function that alters their behavior, since its not really very
descriptive. I know I'll be looking at the code below thinking "hmmm..
clocksource_select(false).. now what does that mean?" at some point not
too far away.
Instead, would leaving clocksource_select() alone, and introducing a
clocksource_select_fallback() for the skipcur behavior, be a more
descriptive choice? The code could very much use the same skipcur logic,
in a __clocksource_select() or something function, but just helps make
the normal usage easier to read.
@@ -645,7 +649,7 @@ static int __init clocksource_done_booti
clocksource_watchdog_kthread(NULL);
mutex_lock(&clocksource_mutex);
- clocksource_select();
+ clocksource_select(false);
mutex_unlock(&clocksource_mutex);
return 0;
}
@@ -739,7 +743,7 @@ int __clocksource_register_scale(struct
mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs);
clocksource_enqueue_watchdog(cs);
- clocksource_select();
+ clocksource_select(false);
mutex_unlock(&clocksource_mutex);
return 0;
}
@@ -766,7 +770,7 @@ int clocksource_register(struct clocksou
mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs);
clocksource_enqueue_watchdog(cs);
- clocksource_select();
+ clocksource_select(false);
mutex_unlock(&clocksource_mutex);
return 0;
}
thanks
-john
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