linux/kernel/time
Thomas Gleixner dd5fd9b91a tick: Clear broadcast pending bit when switching to oneshot
AMD systems which use the C1E workaround in the amd_e400_idle routine
trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU.

The reason is that the idle routine of those AMD systems switches the
cpu into forced broadcast mode early on before the newly brought up
CPU can switch over to high resolution / NOHZ mode. The timer related
CPU1 bringup looks like this:

  clockevent_register_device(local_apic);
  tick_setup(local_apic);
  ...
  idle()
	tick_broadcast_on_off(FORCE);
	tick_broadcast_oneshot_control(ENTER)
	  cpumask_set(cpu, broadcast_oneshot_mask);
	halt();

Now the broadcast interrupt on CPU0 sets CPU1 in the
broadcast_pending_mask and wakes CPU1. So CPU1 continues:

	local_apic_timer_interrupt()
	   tick_handle_periodic();
	   softirq()
	     tick_init_highres();
	       cpumask_clr(cpu, broadcast_oneshot_mask);
	
	tick_broadcast_oneshot_control(ENTER)
	   WARN_ON(cpumask_test(cpu, broadcast_pending_mask);

So while we remove CPU1 from the broadcast_oneshot_mask when we switch
over to highres mode, we do not clear the pending bit, which then
triggers the warning when we go back to idle.

The reason why this is only visible on C1E affected AMD systems is
that the other machines enter the deep sleep states via
acpi_idle/intel_idle and exit the broadcast mode before executing the
remote triggered local_apic_timer_interrupt. So the pending bit is
already cleared when the switch over to highres mode is clearing the
oneshot mask.

The solution is simple: Clear the pending bit together with the mask
bit when we switch over to highres mode.

Stanislaw came up independently with the same patch by enforcing the
C1E workaround and debugging the fallout. I picked mine, because mine
has a changelog :)

Reported-by: poma <pomidorabelisima@gmail.com>
Debugged-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Justin M. Forbes <jforbes@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-13 21:55:54 +01:00
..
alarmtimer.c alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't exist 2013-10-18 16:23:58 -07:00
clockevents.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 10:36:00 +09:00
clocksource.c time: Fix signedness bug in sysfs_get_uname() and its callers 2013-10-18 16:45:58 -07:00
jiffies.c time: Fix overflow when HZ is smaller than 60 2014-02-06 16:01:40 +01:00
Kconfig nohz: Drop generic vtime obsolete dependency on CONFIG_64BIT 2013-09-30 15:37:01 +02:00
Makefile sched_clock: Make ARM's sched_clock generic for all architectures 2013-06-12 14:02:13 -07:00
ntp_internal.h ntp: Rework do_adjtimex to take timespec and tai arguments 2013-04-04 13:18:15 -07:00
ntp.c Linux 3.12-rc3 2013-10-03 07:52:21 +02:00
posix-clock.c kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure 2011-10-31 19:30:05 -04:00
sched_clock.c sched_clock: Disable seqlock lockdep usage in sched_clock() 2014-01-12 10:14:00 +01:00
tick-broadcast.c tick: Clear broadcast pending bit when switching to oneshot 2014-02-13 21:55:54 +01:00
tick-common.c Merge branch 'fortglx/3.14/time' of git://git.linaro.org/people/john.stultz/linux into timers/core 2014-01-12 14:13:31 +01:00
tick-internal.h tick/timekeeping: Call update_wall_time outside the jiffies lock 2013-12-23 11:54:32 -08:00
tick-oneshot.c clockevents: Make minimum delay adjustments configurable 2011-09-08 11:10:56 +02:00
tick-sched.c Merge branch 'timers/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/urgent 2014-01-25 08:27:26 +01:00
timeconv.c time: add function to convert between calendar time and broken-down time for universal use 2009-09-24 07:20:56 -07:00
timekeeping_debug.c power: Add option to log time spent in suspend 2013-05-29 12:57:34 -07:00
timekeeping_internal.h power: Add option to log time spent in suspend 2013-05-29 12:57:34 -07:00
timekeeping.c Merge branch 'fortglx/3.14/time' of git://git.linaro.org/people/john.stultz/linux into timers/core 2014-01-12 14:13:31 +01:00
timer_list.c timer_list: correct the iterator for timer_list 2013-08-28 19:26:38 -07:00
timer_stats.c timer stats: Add a 'Collection: active/inactive' line to timer usage statistics 2013-10-10 09:59:25 +02:00