Commit-ID: 12907fbb1a691807bb0420a27126e15934cb7954
Gitweb: http://git.kernel.org/tip/12907fbb1a691807bb0420a27126e15934cb7954
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Thu, 15 Dec 2016 11:44:28 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sat, 14 Jan 2017 11:29:43 +0100
sched/clock, clocksource: Add optional cs::mark_unstable() method
PeterZ reported that we'd fail to mark the TSC unstable when the
clocksource watchdog finds it unsuitable.
Allow a clocksource to run a custom action when its being marked
unstable and hook up the TSC unstable code.
Reported-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/tsc.c | 11 +++++++++++
include/linux/clocksource.h | 3 +++
kernel/time/clocksource.c | 4 ++++
3 files changed, 18 insertions(+)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index be3a49e..c8174c8 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1106,6 +1106,16 @@ static u64 read_tsc(struct clocksource *cs)
return (u64)rdtsc_ordered();
}
+static void tsc_cs_mark_unstable(struct clocksource *cs)
+{
+ if (tsc_unstable)
+ return;
+ tsc_unstable = 1;
+ clear_sched_clock_stable();
+ disable_sched_clock_irqtime();
+ pr_info("Marking TSC unstable due to clocksource watchdog\n");
+}
+
/*
* .mask MUST be CLOCKSOURCE_MASK(64). See comment above read_tsc()
*/
@@ -1118,6 +1128,7 @@ static struct clocksource clocksource_tsc = {
CLOCK_SOURCE_MUST_VERIFY,
.archdata = { .vclock_mode = VCLOCK_TSC },
.resume = tsc_resume,
+ .mark_unstable = tsc_cs_mark_unstable,
};
void mark_tsc_unstable(char *reason)
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index e315d04..cfc7584 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -62,6 +62,8 @@ struct module;
* @archdata: arch-specific data
* @suspend: suspend function for the clocksource, if necessary
* @resume: resume function for the clocksource, if necessary
+ * @mark_unstable: Optional function to inform the clocksource driver that
+ * the watchdog marked the clocksource unstable
* @owner: module reference, must be set by clocksource in modules
*
* Note: This struct is not used in hotpathes of the timekeeping code
@@ -93,6 +95,7 @@ struct clocksource {
unsigned long flags;
void (*suspend)(struct clocksource *cs);
void (*resume)(struct clocksource *cs);
+ void (*mark_unstable)(struct clocksource *cs);
/* private: */
#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 665985b..93621ae 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -141,6 +141,10 @@ static void __clocksource_unstable(struct clocksource *cs)
{
cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
cs->flags |= CLOCK_SOURCE_UNSTABLE;
+
+ if (cs->mark_unstable)
+ cs->mark_unstable(cs);
+
if (finished_booting)
schedule_work(&watchdog_work);
}
--
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