[PATCH 00/10][RFC] Increased clocksource validation and cleanups

From: John Stultz
Date: Fri Jan 09 2015 - 19:34:39 EST


So this series is the result of earlier discussions with Linus
and his suggestions around improvements to clocksource validation
in the hope we can more easily catch bad hardware.

There's also a few cleanups Linus suggested as well as a few I've been
meaning to get to for awhile.

I'm still feeling cautious about capping the clocksource reads to the
max_cycles values, and even more so with the underflow detection. So
this isn't yet ready for merging, but I wanted to get some initial
review and feedback since its not blowing up in my initial testing.

So let me know what you think, and hopefully we can get this into
shape so it can get more testing and we can evaluate it for 3.20.

thanks
-john

Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>

John Stultz (10):
clocksource: Simplify clocks_calc_max_nsecs logic
clocksource: Simplify logic around clocksource wrapping saftey margins
clocksource: Remove clocksource_max_deferment()
clocksource: Add max_cycles to clocksource structure
time: Add debugging checks to warn if we see delays
time: Cap clocksource reads to the clocksource max_cycles value
time: Try to catch clocksource delta underflows
clocksource: Mostly kill clocksource_register()
sparc: Convert to using clocksource_register_hz()
clocksource: Add some debug info about clocksources being registered

arch/s390/kernel/time.c | 2 +-
arch/sparc/kernel/time_32.c | 6 +-
include/linux/clocksource.h | 15 ++++-
kernel/time/clocksource.c | 143 ++++++++++++++++++--------------------------
kernel/time/jiffies.c | 5 +-
kernel/time/sched_clock.c | 6 +-
kernel/time/timekeeping.c | 34 +++++++++++
7 files changed, 113 insertions(+), 98 deletions(-)

--
1.9.1

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