kernel_optimize_test/arch
Peter Zijlstra acb04058de sched/clock: Fix hotplug crash
Mike reported that he could trigger the WARN_ON_ONCE() in
set_sched_clock_stable() using hotplug.

This exposed a fundamental problem with the interface, we should never
mark the TSC stable if we ever find it to be unstable. Therefore
set_sched_clock_stable() is a broken interface.

The reason it existed is that not having it is a pain, it means all
relevant architecture code needs to call clear_sched_clock_stable()
where appropriate.

Of the three architectures that select HAVE_UNSTABLE_SCHED_CLOCK ia64
and parisc are trivial in that they never called
set_sched_clock_stable(), so add an unconditional call to
clear_sched_clock_stable() to them.

For x86 the story is a lot more involved, and what this patch tries to
do is ensure we preserve the status quo. So even is Cyrix or Transmeta
have usable TSC they never called set_sched_clock_stable() so they now
get an explicit mark unstable.

Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9881b024b7 ("sched/clock: Delay switching sched_clock to stable")
Link: http://lkml.kernel.org/r/20170119133633.GB6536@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-20 02:38:46 +01:00
..
alpha clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
arc 2nd round of ARC udpates for 4.10rc1 2016-12-23 10:22:47 -08:00
arm This pull request contains fixes for the following issues 2017-01-04 16:43:00 +01:00
arm64 arm64: assembler: make adr_l work in modules under KASLR 2017-01-12 18:10:52 +00:00
avr32 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
blackfin Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
c6x clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
cris Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
frv Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
h8300 Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hexagon clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
ia64 sched/clock: Fix hotplug crash 2017-01-20 02:38:46 +01:00
m32r Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
m68k clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
metag Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:05:56 -08:00
microblaze clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
mips KVM fixes for v4.10-rc3 2017-01-06 15:27:17 -08:00
mn10300 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
nios2 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
openrisc openrisc: Add _text symbol to fix ksym build error 2017-01-02 10:35:11 +09:00
parisc sched/clock: Fix hotplug crash 2017-01-20 02:38:46 +01:00
powerpc sched/cputime: Rename vtime_account_user() to vtime_flush() 2017-01-14 09:54:13 +01:00
s390 sched/cputime: Rename vtime_account_user() to vtime_flush() 2017-01-14 09:54:13 +01:00
score Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sh Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sparc clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
tile Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
um clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
unicore32 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
x86 sched/clock: Fix hotplug crash 2017-01-20 02:38:46 +01:00
xtensa Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
.gitignore
Kconfig powerpc: ima: get the kexec buffer passed by the previous kernel 2016-12-20 09:48:40 -08:00