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Subject[RFC PATCH 3/4] x86/tsc: Use bool, not pointer, for ART availability
Date
So far, ART availability has been implicitly encoded in
art_related_clocksource, which is NULL if ART is not available.

Replace art_related_clocksource by bool have_art to explicitly indicate
ART availability.

This should reduce the changes during a tree-wide switch of struct
system_counterval_t.cs to enum clocksource_ids (when the clocksource
pointer will not be needed any more).

Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
---
arch/x86/kernel/tsc.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 132045be76d0..e56cc4e97d0d 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -54,7 +54,7 @@ static int __read_mostly tsc_force_recalibrate;
static u32 art_to_tsc_numerator;
static u32 art_to_tsc_denominator;
static u64 art_to_tsc_offset;
-static struct clocksource *art_related_clocksource;
+static bool have_art;

struct cyc2ns {
struct cyc2ns_data data[2]; /* 0 + 2*16 = 32 */
@@ -1312,8 +1312,10 @@ struct system_counterval_t convert_art_to_tsc(u64 art)
do_div(tmp, art_to_tsc_denominator);
res += tmp + art_to_tsc_offset;

- return (struct system_counterval_t) {.cs = art_related_clocksource,
- .cycles = res};
+ return (struct system_counterval_t) {
+ .cs = have_art ? &clocksource_tsc : NULL,
+ .cycles = res
+ };
}
EXPORT_SYMBOL(convert_art_to_tsc);

@@ -1350,8 +1352,10 @@ struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
do_div(tmp, USEC_PER_SEC);
res += tmp;

- return (struct system_counterval_t) { .cs = art_related_clocksource,
- .cycles = res};
+ return (struct system_counterval_t) {
+ .cs = have_art ? &clocksource_tsc : NULL,
+ .cycles = res
+ };
}
EXPORT_SYMBOL(convert_art_ns_to_tsc);

@@ -1458,7 +1462,7 @@ static void tsc_refine_calibration_work(struct work_struct *work)
goto unreg;

if (boot_cpu_has(X86_FEATURE_ART))
- art_related_clocksource = &clocksource_tsc;
+ have_art = true;
clocksource_register_khz(&clocksource_tsc, tsc_khz);
unreg:
clocksource_unregister(&clocksource_tsc_early);
@@ -1484,7 +1488,7 @@ static int __init init_tsc_clocksource(void)
*/
if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
if (boot_cpu_has(X86_FEATURE_ART))
- art_related_clocksource = &clocksource_tsc;
+ have_art = true;
clocksource_register_khz(&clocksource_tsc, tsc_khz);
clocksource_unregister(&clocksource_tsc_early);

--
2.39.2
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