[tip:timers/urgent] x86/tsc: Fix mark_tsc_unstable()

From: tip-bot for Peter Zijlstra
Date: Wed May 02 2018 - 10:14:50 EST


Commit-ID: e3b4f79025e0a4eb7e2a2c7d24dadfa1e38893b0
Gitweb: https://git.kernel.org/tip/e3b4f79025e0a4eb7e2a2c7d24dadfa1e38893b0
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 30 Apr 2018 12:00:12 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 2 May 2018 16:10:40 +0200

x86/tsc: Fix mark_tsc_unstable()

mark_tsc_unstable() also needs to affect tsc_early, Now that
clocksource_mark_unstable() can be used on a clocksource irrespective of
its registration state, use it on both tsc_early and tsc.

This does however require cs->list to be initialized empty, otherwise it
cannot tell the registation state before registation.

Fixes: aa83c45762a2 ("x86/tsc: Introduce early tsc clocksource")
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Diego Viola <diego.viola@xxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: len.brown@xxxxxxxxx
Cc: rjw@xxxxxxxxxxxxx
Cc: rui.zhang@xxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20180430100344.533326547@xxxxxxxxxxxxx

---
arch/x86/kernel/tsc.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 23f36bc236ba..74392d9d51e0 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1067,6 +1067,7 @@ static struct clocksource clocksource_tsc_early = {
.resume = tsc_resume,
.mark_unstable = tsc_cs_mark_unstable,
.tick_stable = tsc_cs_tick_stable,
+ .list = LIST_HEAD_INIT(clocksource_tsc_early.list),
};

/*
@@ -1086,6 +1087,7 @@ static struct clocksource clocksource_tsc = {
.resume = tsc_resume,
.mark_unstable = tsc_cs_mark_unstable,
.tick_stable = tsc_cs_tick_stable,
+ .list = LIST_HEAD_INIT(clocksource_tsc.list),
};

void mark_tsc_unstable(char *reason)
@@ -1098,13 +1100,9 @@ void mark_tsc_unstable(char *reason)
clear_sched_clock_stable();
disable_sched_clock_irqtime();
pr_info("Marking TSC unstable due to %s\n", reason);
- /* Change only the rating, when not registered */
- if (clocksource_tsc.mult) {
- clocksource_mark_unstable(&clocksource_tsc);
- } else {
- clocksource_tsc.flags |= CLOCK_SOURCE_UNSTABLE;
- clocksource_tsc.rating = 0;
- }
+
+ clocksource_mark_unstable(&clocksource_tsc_early);
+ clocksource_mark_unstable(&clocksource_tsc);
}

EXPORT_SYMBOL_GPL(mark_tsc_unstable);