linux-toradex.git/kernel/time, branch v2.6.27.17

clocksource: introduce clocksource_forward_now()

2009-01-25T00:36:24+00:00

commit 9a055117d3d9cb562f83f8d4cd88772761f4cab0 upstream.

To keep the raw monotonic patch simple first introduce
clocksource_forward_now(), which takes care of the offset since the last
update_wall_time() call and adds it to the clock, so there is no need
anymore to deal with it explicitly at various places, which need to make
significant changes to the clock.

This is also gets rid of the timekeeping_suspend_nsecs, instead of
waiting until resume, the value is accumulated during suspend. In the end
there is only a single user of __get_nsec_offset() left, so I integrated
it back to getnstimeofday().

Signed-off-by: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched_clock: prevent scd->clock from moving backwards, take #2

2009-01-18T18:35:28+00:00

commit 1c5745aa380efb6417b5681104b007c8612fb496 upstream.

Redo:

  5b7dba4: sched_clock: prevent scd->clock from moving backwards

which had to be reverted due to s2ram hangs:

  ca7e716: Revert "sched_clock: prevent scd->clock from moving backwards"

... this time with resume restoring GTOD later in the sequence
taken into account as well.

The "timekeeping_suspended" flag is not very nice but we cannot call into
GTOD before it has been properly resumed and the scheduler will run very
early in the resume sequence.

Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

clockevents: check broadcast tick device not the clock events device

2008-10-04T08:51:07+00:00

Impact: jiffies increment too fast.

Hugh Dickins noted that with NOHZ=n and HIGHRES=n jiffies get
incremented too fast. The reason is a wrong check in the broadcast
enter/exit code, which keeps the local apic timer in periodic mode
when the switch happens.

Signed-off-by: Thomas Gleixner

hrtimer: prevent migration of per CPU hrtimers

2008-09-29T15:09:14+00:00

Impact: per CPU hrtimers can be migrated from a dead CPU

The hrtimer code has no knowledge about per CPU timers, but we need to
prevent the migration of such timers and warn when such a timer is
active at migration time.

Explicitely mark the timers as per CPU and use a more understandable
mode descriptor for the interrupts safe unlocked callback mode, which
is used by hrtimer_sleeper and the scheduler code.

Signed-off-by: Thomas Gleixner

timers: fix build error in !oneshot case

2008-09-23T10:57:00+00:00

 kernel/time/tick-common.c: In function ‘tick_setup_periodic’:
 kernel/time/tick-common.c:113: error: implicit declaration of function ‘tick_broadcast_oneshot_active’

Signed-off-by: Ingo Molnar

clockevents: prevent mode mismatch on cpu online

2008-09-23T09:38:53+00:00

Impact: timer hang on CPU online observed on AMD C1E systems

When a CPU is brought online then the broadcast machinery can
be in the one shot state already. Check this and setup the timer 
device of the new CPU in one shot mode so the broadcast code
can pick up the next_event value correctly.

Another AMD C1E oddity, as we switch to broadcast immediately and
not after the full bring up via the ACPI cpu idle code.

Signed-off-by: Thomas Gleixner

clockevents: check broadcast device not tick device

2008-09-23T09:38:53+00:00

Impact: Possible hang on CPU online observed on AMD C1E machines.

The broadcast setup code looks at the mode of the tick device to
determine whether it needs to be shut down or setup. This is wrong
when the broadcast mode is set to one shot already. This can happen
when a CPU is brought online as it goes through the periodic setup
first.

The problem went unnoticed as sane systems do not call into that code
before the switch to one shot for the clock event device happens.
The AMD C1E idle routine switches over immediately and thereby shuts
down the just setup device before the first interrupt happens.

Signed-off-by: Thomas Gleixner

clockevents: prevent stale tick_next_period for onlining CPUs

2008-09-23T09:38:53+00:00

Impact: possible hang on CPU onlining in timer one shot mode.

The tick_next_period variable is only used during boot on nohz/highres
enabled systems, but for CPU onlining it needs to be maintained when
the per cpu clock events device operates in one shot mode.

Signed-off-by: Thomas Gleixner

clockevents: prevent cpu online to interfere with nohz

2008-09-23T09:38:52+00:00

Impact: rare hang which can be triggered on CPU online.

tick_do_timer_cpu keeps track of the CPU which updates jiffies
via do_timer. The value -1 is used to signal, that currently no
CPU is doing this. There are two cases, where the variable can 
have this state:

 boot:
    necessary for systems where the boot cpu id can be != 0

 nohz long idle sleep:
    When the CPU which did the jiffies update last goes into
    a long idle sleep it drops the update jiffies duty so
    another CPU which is not idle can pick it up and keep
    jiffies going.

Using the same value for both situations is wrong, as the CPU online
code can see the -1 state when the timer of the newly onlined CPU is
setup. The setup for a newly onlined CPU goes through periodic mode
and can pick up the do_timer duty without being aware of the nohz /
highres mode of the already running system.

Use two separate states and make them constants to avoid magic
numbers confusion. 

Signed-off-by: Thomas Gleixner

clockevents: make device shutdown robust

2008-09-16T20:47:02+00:00

The device shut down does not cleanup the next_event variable of the
clock event device. So when the device is reactivated the possible
stale next_event value can prevent the device to be reprogrammed as it
claims to wait on a event already.

This is the root cause of the resurfacing suspend/resume problem,
where systems need key press to come back to life.

Fix this by setting next_event to KTIME_MAX when the device is shut
down. Use a separate function for shutdown which takes care of that
and only keep the direct set mode call in the broadcast code, where we
can not touch the next_event value.

Signed-off-by: Thomas Gleixner