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Thomas Gleixner 07f4beb0b5 tick: Clear broadcast active bit when switching to oneshot 
The first cpu which switches from periodic to oneshot mode switches
also the broadcast device into oneshot mode. The broadcast device
serves as a backup for per cpu timers which stop in deeper
C-states. To avoid starvation of the cpus which might be in idle and
depend on broadcast mode it marks the other cpus as broadcast active
and sets the brodcast expiry value of those cpus to the next tick.

The oneshot mode broadcast bit for the other cpus is sticky and gets
only cleared when those cpus exit idle. If a cpu was not idle while
the bit got set in consequence the bit prevents that the broadcast
device is armed on behalf of that cpu when it enters idle for the
first time after it switched to oneshot mode.

In most cases that goes unnoticed as one of the other cpus has usually
a timer pending which keeps the broadcast device armed with a short
timeout. Now if the only cpu which has a short timer active has the
bit set then the broadcast device will not be armed on behalf of that
cpu and will fire way after the expected timer expiry. In the case of
Christians bug report it took ~145 seconds which is about half of the
wrap around time of HPET (the limit for that device) due to the fact
that all other cpus had no timers armed which expired before the 145
seconds timeframe.

The solution is simply to clear the broadcast active bit
unconditionally when a cpu switches to oneshot mode after the first
cpu switched the broadcast device over. It's not idle at that point
otherwise it would not be executing that code.

[ I fundamentally hate that broadcast crap. Why the heck thought some
  folks that when going into deep idle it's a brilliant concept to
  switch off the last device which brings the cpu back from that
  state? ]

Thanks to Christian for providing all the valuable debug information!

Reported-and-tested-by: Christian Hoffmann <email@christianhoffmann.info>
Cc: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1105161105170.3078%40ionos%3E
Cc: stable@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-16 23:35:41 +02:00
..
debug Fix common misspellings 2011-03-31 11:26:23 -03:00
gcov Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-03-20 18:14:55 -07:00
irq genirq: Fix typo CONFIG_GENIRC_IRQ_SHOW_LEVEL 2011-05-02 21:16:37 +02:00
power PM: Fix error code paths executed after failing syscore_suspend() 2011-04-18 23:58:59 +02:00
time tick: Clear broadcast active bit when switching to oneshot 2011-05-16 23:35:41 +02:00
trace Merge branch 'tip/perf/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/urgent 2011-04-27 10:31:29 +02:00
.gitignore
acct.c
async.c
audit_tree.c Fix common misspellings 2011-03-31 11:26:23 -03:00
audit_watch.c kill path_lookup() 2011-03-14 09:15:23 -04:00
audit.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
audit.h audit: make functions static 2010-10-30 01:42:19 -04:00
auditfilter.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
auditsc.c Fix common misspellings 2011-03-31 11:26:23 -03:00
backtracetest.c
bounds.c memcg: remove direct page_cgroup-to-page pointer 2011-03-23 19:46:28 -07:00
capability.c userns: make has_capability* into real functions 2011-03-23 19:47:06 -07:00
cgroup_freezer.c cgroup_freezer: update_freezer_state() does incorrect state transitions 2010-10-27 18:03:08 -07:00
cgroup.c Fix common misspellings 2011-03-31 11:26:23 -03:00
compat.c posix-timers: Introduce a syscall for clock tuning. 2011-02-02 15:28:19 +01:00
configs.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
cpu.c Fix common misspellings 2011-03-31 11:26:23 -03:00
cpuset.c cpuset: hold callback_mutex in cpuset_post_clone() 2011-03-23 19:46:35 -07:00
crash_dump.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
cred.c userns: security: make capabilities relative to the user namespace 2011-03-23 19:47:02 -07:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c Fix common misspellings 2011-03-31 11:26:23 -03:00
extable.c
fork.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
freezer.c Freezer: Fix a race during freezing of TASK_STOPPED tasks 2010-12-24 15:02:40 +01:00
futex_compat.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
futex.c futex: Set FLAGS_HAS_TIMEOUT during futex_wait restart setup 2011-04-15 16:34:32 +02:00
groups.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
hrtimer.c hrtimer: Initialize CLOCK_ID to HRTIMER_BASE table statically 2011-04-29 10:57:11 +02:00
hung_task.c
hw_breakpoint.c perf: Dynamic pmu types 2010-12-16 11:36:43 +01:00
irq_work.c irq_work: Use per cpu atomics instead of regular atomics 2010-12-18 15:54:48 +01:00
itimer.c
jump_label.c jump label: Make arch_jump_label_text_poke_early() optional 2010-10-29 12:56:13 -04:00
kallsyms.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-25 17:52:22 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c PM: Add missing syscore_suspend() and syscore_resume() calls 2011-04-20 00:36:11 +02:00
kfifo.c kfifo: fix scatterlist usage 2010-10-01 10:50:58 -07:00
kmod.c
kprobes.c Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-01-07 17:02:58 -08:00
ksysfs.c
kthread.c Fix common misspellings 2011-03-31 11:26:23 -03:00
latencytop.c Fix common misspellings 2011-03-31 11:26:23 -03:00
lockdep_internals.h
lockdep_proc.c lockdep: Remove unused 'factor' variable from lockdep_stats_show() 2011-03-23 13:54:47 +01:00
lockdep_states.h
lockdep.c Fix common misspellings 2011-03-31 11:26:23 -03:00
Makefile crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
module.c Fix common misspellings 2011-03-31 11:26:23 -03:00
mutex-debug.c
mutex-debug.h
mutex.c Fix common misspellings 2011-03-31 11:26:23 -03:00
mutex.h
notifier.c
ns_cgroup.c cgroup: notify ns_cgroup deprecated 2010-10-27 18:03:09 -07:00
nsproxy.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
padata.c Fix common misspellings 2011-03-31 11:26:23 -03:00
panic.c move x86 specific oops=panic to generic code 2011-03-22 17:44:11 -07:00
params.c Fix common misspellings 2011-03-31 11:26:23 -03:00
perf_event.c perf_event: Fix cgrp event scheduling bug in perf_enable_on_exec() 2011-04-11 11:07:55 +02:00
pid_namespace.c pidns: call pid_ns_prepare_proc() from create_pid_namespace() 2011-03-23 19:46:58 -07:00
pid.c next_pidmap: fix overflow condition 2011-04-18 10:35:30 -07:00
pm_qos_params.c PM QoS: Make pm_qos settings readable 2011-03-15 00:43:18 +01:00
posix-cpu-timers.c Fix common misspellings 2011-03-31 11:26:23 -03:00
posix-timers.c Fix common misspellings 2011-03-31 11:26:23 -03:00
printk.c printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig 2011-03-22 17:44:13 -07:00
profile.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
ptrace.c userns: allow ptrace from non-init user namespaces 2011-03-23 19:47:05 -07:00
range.c kernel/range.c: fix clean_sort_range() for the case of full array 2010-11-12 07:55:31 -08:00
rcupdate.c rcu: add comment saying why DEBUG_OBJECTS_RCU_HEAD depends on PREEMPT. 2011-03-04 08:05:41 -08:00
rcutiny_plugin.h rcu: call __rcu_read_unlock() in exit_rcu for tiny RCU 2011-03-04 08:05:08 -08:00
rcutiny.c rcu: avoid pointless blocked-task warnings 2011-01-14 04:58:08 -08:00
rcutorture.c rcutorture: Get rid of duplicate sched.h include 2011-03-04 08:05:17 -08:00
rcutree_plugin.h rcu: increase synchronize_sched_expedited() batching 2010-12-17 12:34:08 -08:00
rcutree_trace.c rcu,cleanup: simplify the code when cpu is dying 2010-11-29 22:01:58 -08:00
rcutree.c Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-01-07 17:02:58 -08:00
rcutree.h rcu: limit rcu_node leaf-level fanout 2010-12-17 12:34:20 -08:00
relay.c Clean up relay_alloc_page_array() slightly by using vzalloc rather than vmalloc and memset 2010-11-05 08:21:34 -07:00
res_counter.c memcg: res_counter_read_u64(): fix potential races on 32-bit machines 2011-03-23 19:46:22 -07:00
resource.c resources: add arch hook for preventing allocation in reserved areas 2010-12-17 10:01:09 -08:00
rtmutex_common.h rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.h
rtmutex-tester.c rtmutex: tester: Remove the remaining BKL leftovers 2011-02-22 22:07:22 +01:00
rtmutex.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex.h
rwsem.c
sched_autogroup.c Fix common misspellings 2011-03-31 11:26:23 -03:00
sched_autogroup.h sched, autogroup: Stop going ahead if autogroup is disabled 2011-02-23 11:33:59 +01:00
sched_clock.c sched: Add some clock info to sched_debug 2010-11-23 10:29:08 +01:00
sched_cpupri.c
sched_cpupri.h
sched_debug.c sched: Use a buddy to implement yield_task_fair() 2011-02-03 14:20:33 +01:00
sched_fair.c sched: Fix erroneous all_pinned logic 2011-04-11 11:08:54 +02:00
sched_features.h sched: Rewrite tg_shares_up) 2010-11-18 13:27:46 +01:00
sched_idletask.c sched, doc: Update sched-design-CFS.txt 2011-03-23 14:09:41 +01:00
sched_rt.c Fix common misspellings 2011-03-31 11:26:23 -03:00
sched_stats.h sched_stat: Update sched_info_queue/dequeue() code comments 2010-10-24 13:29:01 +02:00
sched_stoptask.c sched, doc: Update sched-design-CFS.txt 2011-03-23 14:09:41 +01:00
sched.c block: let io_schedule() flush the plug inline 2011-04-16 13:27:55 +02:00
seccomp.c
semaphore.c
signal.c signal.c: fix erroneous syscall kernel-doc 2011-04-08 11:05:24 -07:00
smp.c smp: move smp setup functions to kernel/smp.c 2011-03-22 17:44:11 -07:00
softirq.c Fix common misspellings 2011-03-31 11:26:23 -03:00
spinlock.c
srcu.c rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status 2011-01-14 04:56:49 -08:00
stacktrace.c
stop_machine.c kthread: use kthread_create_on_node() 2011-03-22 17:44:01 -07:00
sys_ni.c vfs: Add open by file handle support 2011-03-15 02:21:44 -04:00
sys.c userns: user namespaces: convert all capable checks in kernel/sys.c 2011-03-23 19:47:06 -07:00
sysctl_binary.c open-style analog of vfs_path_lookup() 2011-03-14 09:15:28 -04:00
sysctl_check.c sysctl_check: drop dead code 2011-03-23 19:46:51 -07:00
sysctl.c sysctl: restrict write access to dmesg_restrict 2011-03-23 19:46:54 -07:00
taskstats.c taskstats: use appropriate printk priority level 2011-03-23 19:47:14 -07:00
test_kprobes.c kprobes: Fix selftest to clear flags field for reusing probes 2010-10-14 08:55:27 +02:00
time.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
timeconst.pl
timer.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
tracepoint.c tracepoints: Fix section alignment using pointer array 2011-02-03 09:28:46 -05:00
tsacct.c taskstats: use real microsecond granularity for CPU times 2010-10-27 18:03:17 -07:00
uid16.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
up.c
user_namespace.c user_ns: improve the user_ns on-the-slab packaging 2011-01-13 08:03:18 -08:00
user-return-notifier.c Fix common misspellings 2011-03-31 11:26:23 -03:00
user.c userns: add a user_namespace as creator/owner of uts_namespace 2011-03-23 19:46:59 -07:00
utsname_sysctl.c
utsname.c userns: allow sethostname in a container 2011-03-23 19:47:03 -07:00
wait.c Fix common misspellings 2011-03-31 11:26:23 -03:00
watchdog.c kernel/watchdog.c: disable nmi perf event in the error path of enabling watchdog 2011-04-28 11:28:21 -07:00
workqueue_sched.h
workqueue.c workqueue: fix deadlock in worker_maybe_bind_and_lock() 2011-04-29 18:08:37 +02:00