sched/clock: Fixup early initialization

The code would assume sched_clock_stable() and switch to !stable
later, this switch brings a discontinuity in time.

The discontinuity on switching from stable to unstable was always
present, but previously we would set stable/unstable before
initializing TSC and usually stick to the one we start out with.

So the static_key bits brought an extra switch where there previously
wasn't one.

Things are further complicated by the fact that we cannot use
static_key as early as we usually call set_sched_clock_stable().

Fix things by tracking the stable state in a regular variable and only
set the static_key to the right state on sched_clock_init(), which is
ran right after late_time_init->tsc_init().

Before this we would not be using the TSC anyway.

Reported-and-Tested-by: Sasha Levin <[email protected]>
Reported-by: [email protected]
Fixes: 35af99e646c7 ("sched/clock, x86: Use a static_key for sched_clock_stable")
Cc: [email protected]
Cc: Mike Galbraith <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: John Stultz <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Eliezer Tamir <[email protected]>
Cc: [email protected]
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions