linux-toradex.git/kernel/time/ntp.c, branch v3.15-rc6

timekeeping: Move clock sync work to power efficient workqueue

2014-02-07T14:34:28+00:00

For better use of CPU idle time, allow the scheduler to select the CPU
on which the CMOS clock sync work would be scheduled. This improves
idle residency time and conserver power.

This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.

Signed-off-by: Shaibal Dutta 
[zoran.markovic@linaro.org: Added commit message. Aligned code.]
Signed-off-by: Zoran Markovic 
Cc: John Stultz 
Link: http://lkml.kernel.org/r/1391195904-12497-1-git-send-email-zoran.markovic@linaro.org
Signed-off-by: Thomas Gleixner

Merge tag 'v3.12-rc3' into timers/core

2013-10-03T05:52:21+00:00

Merge Linux 3.12-rc3 - refresh the tree with the latest fixes before merging new bits.

Signed-off-by: Ingo Molnar

timekeeping: Fix HRTICK related deadlock from ntp lock changes

2013-09-12T05:49:51+00:00

Gerlando Falauto reported that when HRTICK is enabled, it is
possible to trigger system deadlocks. These were hard to
reproduce, as HRTICK has been broken in the past, but seemed
to be connected to the timekeeping_seq lock.

Since seqlock/seqcount's aren't supported w/ lockdep, I added
some extra spinlock based locking and triggered the following
lockdep output:

[   15.849182] ntpd/4062 is trying to acquire lock:
[   15.849765]  (&(&pool->lock)->rlock){..-...}, at: [] __queue_work+0x145/0x480
[   15.850051]
[   15.850051] but task is already holding lock:
[   15.850051]  (timekeeper_lock){-.-.-.}, at: [] do_adjtimex+0x7f/0x100



[   15.850051] Chain exists of: &(&pool->lock)->rlock --> &p->pi_lock --> timekeeper_lock
[   15.850051]  Possible unsafe locking scenario:
[   15.850051]
[   15.850051]        CPU0                    CPU1
[   15.850051]        ----                    ----
[   15.850051]   lock(timekeeper_lock);
[   15.850051]                                lock(&p->pi_lock);
[   15.850051] lock(timekeeper_lock);
[   15.850051] lock(&(&pool->lock)->rlock);
[   15.850051]
[   15.850051]  *** DEADLOCK ***

The deadlock was introduced by 06c017fdd4dc48451a ("timekeeping:
Hold timekeepering locks in do_adjtimex and hardpps") in 3.10

This patch avoids this deadlock, by moving the call to
schedule_delayed_work() outside of the timekeeper lock
critical section.

Reported-by: Gerlando Falauto 
Tested-by: Lin Ming 
Signed-off-by: John Stultz 
Cc: Mathieu Desnoyers 
Cc: stable  #3.11, 3.10
Link: http://lkml.kernel.org/r/1378943457-27314-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar

ntp: Make periodic RTC update more reliable

2013-08-22T19:33:38+00:00

The current code requires that the scheduled update of the RTC happens
in the closest tick to the half of the second. This seems to be
difficult to achieve reliably. The scheduled work may be missing the
target time by a tick or two and be constantly rescheduled every second.

Relax the limit to 10 ticks. As a typical RTC drifts in the 11-minute
update interval by several milliseconds, this shouldn't affect the
overall accuracy of the RTC much.

Signed-off-by: Miroslav Lichvar 
Signed-off-by: John Stultz

ntp: Remove unused variable flags in __hardpps

2013-05-28T20:45:19+00:00

kernel/time/ntp.c: In function ‘__hardpps’:
kernel/time/ntp.c:877: warning: unused variable ‘flags’

commit a076b2146fabb0894cae5e0189a8ba3f1502d737 ("ntp: Remove ntp_lock,
using the timekeeping locks to protect ntp state") removed its users,
but not the actual variable.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: John Stultz

ntp: Remove ntp_lock, using the timekeeping locks to protect ntp state

2013-04-04T20:18:17+00:00

In order to properly handle the NTP state in future changes to the
timekeeping lock management, this patch moves the management of
all of the ntp state under the timekeeping locks.

This allows us to remove the ntp_lock.

Cc: Thomas Gleixner 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Signed-off-by: John Stultz

timekeeping: Move ADJ_SETOFFSET to top level do_adjtimex()

2013-04-04T20:18:15+00:00

Since ADJ_SETOFFSET adjusts the timekeeping state, process
it as part of the top level do_adjtimex() function in
timekeeping.c.

This avoids deadlocks that could occur once we change the
ntp locking rules.

Cc: Thomas Gleixner 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Signed-off-by: John Stultz

ntp: Rework do_adjtimex to take timespec and tai arguments

2013-04-04T20:18:15+00:00

In order to change the locking rules, we need to provide
the timespec and tai values rather then having the ntp
logic acquire these values itself.

Cc: Thomas Gleixner 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Signed-off-by: John Stultz

ntp: Move timex validation to timekeeping do_adjtimex call.

2013-04-04T20:18:14+00:00

Move logic that does not need the ntp state to be done
in the timekeeping do_adjtimex() call.

Cc: Thomas Gleixner 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Signed-off-by: John Stultz

ntp: Move do_adjtimex() and hardpps() functions to timekeeping.c

2013-04-04T20:18:14+00:00

In preparation for changing the ntp locking rules, move
do_adjtimex and hardpps accessor functions to timekeeping.c,
but keep the code logic in ntp.c.

This patch also introduces a ntp_internal.h file so timekeeping
specific interfaces of ntp.c can be more limitedly shared with
timekeeping.c.

Cc: Thomas Gleixner 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Signed-off-by: John Stultz