Avoids sending a signal to alarm timers created with sigev_notify set to
SIGEV_NONE by checking for that special case in the timeout callback.

The regular posix timers avoid sending signals to SIGEV_NONE timers by
not scheduling any callbacks for them in the first place.  Although it
would be possible to do something similar for alarm timers, it's simpler
to handle this as a special case in the timeout.

Prior to this patch, the alarm timer would ignore the sigev_notify value
and try to deliver signals to the process anyway.  Even worse, the
sanity check for the value of sigev_signo is skipped when SIGEV_NONE was
specified, so the signal number could be bogus.  If sigev_signo was an
unitialized value (as it often would be if SIGEV_NONE is used), then
it's hard to predict which signal will be sent.

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: NRichard Larocque <rlarocque@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Returns the time remaining for an alarm timer, rather than the time at
which it is scheduled to expire.  If the timer has already expired or it
is not currently scheduled, the it_value's members are set to zero.

This new behavior matches that of the other posix-timers and the POSIX
specifications.

This is a change in user-visible behavior, and may break existing
applications.  Hopefully, few users rely on the old incorrect behavior.

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: NRichard Larocque <rlarocque@google.com>
[jstultz: minor style tweak]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Sharvil noticed with the posix timer_settime interface, using the
CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users
tried to specify a relative time timer, it would incorrectly be
treated as absolute regardless of the state of the flags argument.

This patch corrects this, properly checking the absolute/relative flag,
as well as adds further error checking that no invalid flag bits are set.
Reported-by: NSharvil Nanavati <sharvil@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Cc: stable <stable@vger.kernel.org> #3.0+
Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Export symbol of alarmtimer_get_rtcdev so that it is used by
any driver when built as module like,
drivers/staging/android/alarm-dev.c.

CC: John Stultz <john.stultz@linaro.org>
CC: Marcus Gelderie <redmnic@gmail.com>
Signed-off-by: NPramod Gurav <pramod.gurav.etc@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide
on ARM. (http://bugs.ruby-lang.org/issues/9008)

Because of, commit 1c6b39ad (alarmtimers: Return -ENOTSUPP if no
RTC device is present) intruduced to return ENOTSUPP when
clock_get{time,res} can't find a RTC device. However this is incorrect.

First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the
closest userland equivlents).

Second, Posix and Linux man pages agree that clock_gettime and
clock_getres should return EINVAL if clk_id argument is invalid.
While the arugment that the clockid is valid, but just not supported
on this hardware could be made, this is just a technicality that
doesn't help userspace applicaitons, and only complicates error
handling.

Thus, this patch changes the code to use EINVAL.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: stable <stable@vger.kernel.org>  #3.0 and up
Reported-by: NVit Ondruch <v.ondruch@tiscali.cz>
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
[jstultz: Tweaks to commit message to include full rational]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Export symbols so they can be used by
drivers/staging/android/alarm-dev.c if it is built as a module.
So far alarm-dev is built-in but module support is planned (see
drivers/staging/android/TODO).
Signed-off-by: NMarcus Gelderie <redmnic@gmail.com>
[jstultz: tweaked commit message, also export newly added functions]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Add functions needed for hooking up alarmtimer to timerfd:

* alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
  the expires time has already been updated (as with alarm_forward).

* alarm_forward_now: Similar to hrtimer_forward_now, move the expires
  time forward to an interval from the current time of the associated clock.

* alarm_start_relative: Start an alarmtimer with an expires time relative to
  the current time of the associated clock.

* alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
  amount of time remaining until alarm expiry.
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Now that alarmtimer_remove has been simplified, change
its name to _dequeue to better match its paired _enqueue
function.

Cc: Arve Hjønnevåg <arve@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Arve Hjønnevåg reported numerous crashes from the
"BUG_ON(timer->state != HRTIMER_STATE_CALLBACK)" check
in __run_hrtimer after it called alarmtimer_fired.

It ends up the alarmtimer code was not properly handling
possible failures of hrtimer_try_to_cancel, and because
these faulres occur when the underlying base hrtimer is
being run, this limits the ability to properly handle
modifications to any alarmtimers on that base.

Because much of the logic duplicates the hrtimer logic,
it seems that we might as well have a per-alarmtimer
hrtimer, and avoid the extra complextity of trying to
multiplex many alarmtimers off of one hrtimer.

Thus this patch moves the hrtimer to the alarm structure
and simplifies the management logic.

Changelog:
v2:
* Includes a fix for double alarm_start calls found by
  Arve

Cc: Arve Hjønnevåg <arve@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: NArve Hjønnevåg <arve@android.com>
Tested-by: NArve Hjønnevåg <arve@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

alarmtimer suspend return -EBUSY if the next alarm will fire in less
than 2 seconds.  This allows one RTC seconds tick to occur subsequent
to this check before the alarm wakeup time is set, ensuring the wakeup
time is still in the future (assuming the RTC does not tick one more
second prior to setting the alarm).

If suspend is rejected due to an imminent alarm, hold a wakeup source
for 2 seconds to process the alarm prior to reattempting suspend.

If setting the alarm incurs an -ETIME for an alarm set in the past,
or any other problem setting the alarm, abort suspend and hold a
wakelock for 1 second while the alarm is allowed to be serviced or
other hopefully transient conditions preventing the alarm clear up.
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The Android alarm interface provides a settime call that sets both
the alarmtimer RTC device and CLOCK_REALTIME to the same value.

Since there may be multiple rtc devices, provide a hook to access the
one the alarmtimer infrastructure is using.

CC: Colin Cross <ccross@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

rtc_timer_init() is not available when CONFIG_RTC_CLASS=n. Provide a
proper wrapper in the RTC section of alarmtimer.c
Reported-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>

jonghwan Choi reported seeing warnings with the alarmtimer
code at suspend/resume time, and pointed out that the
rtctimer isn't being properly initialized.

This patch corrects this issue.
Reported-by: Njonghwan Choi <jhbird.choi@gmail.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The expiry function compares the timer against current time and does
not expire the timer when the expiry time is >= now. That's wrong. If
the timer is set for now, then it must expire.

Make the condition expiry > now for breaking out the loop.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: stable@kernel.org

commit 8bc0dafb (alarmtimers: Rework RTC device selection using class
interface) did not implement required error checks. Add them.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This allows cleaner detection of the RTC device being registered, rather
then probing any time someone calls alarmtimer_get_rtcdev.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

There's a number of edge cases when cancelling a alarm, so
to be sure we accurately do so, introduce try_to_cancel, which
returns proper failure errors if it cannot. Also modify cancel
to spin until the alarm is properly disabled.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

In order to allow for functionality like try_to_cancel, add
more refined  state tracking (similar to hrtimers).

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Now that periodic alarmtimers are managed by the handler function,
remove the period value from the alarm structure and let the handlers
manage the interval on their own.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Now that the alarmtimers code has been refactored, the interval
cap limit can be removed.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

In order to avoid wasting time expiring and re-adding very high freq
periodic alarmtimers, introduce alarm_forward() which is similar to
hrtimer_forward and moves the timer to the next future expiration time
and returns the number of overruns.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This patch pushes the periodic alarmtimer re-arming down into the alarmtimer
handler, mimicking how hrtimers handle this.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

In order to properly fix the denial of service issue with high freq
periodic alarm timers, we need to push the re-arming logic into the
alarm timer handler, much as the hrtimer code does.

This patch introduces alarmtimer_restart enum and changes the
alarmtimer handler declarations to use it as a return value. Further,
to ease following changes, it extends the alarmtimer handler functions
to also take the time at expiration. No logic is yet modified.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Its possible to jam up the alarm timers by setting very small interval
timers, which will cause the alarmtimer subsystem to spend all of its time
firing and restarting timers. This can effectivly lock up a box.

A deeper fix is needed, closely mimicking the hrtimer code, but for now
just cap the interval to 100us to avoid userland hanging the system.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Following common_timer_get, zero out the itimerspec passed in.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

We don't check if old_setting is non null before assigning it, so
correct this.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Toralf Förster and Richard Weinberger noted that if there is
no RTC device, the alarm timers core prints out an annoying
"ALARM timers will not wake from suspend" message.

This warning has been removed in a previous patch, however
the issue still remains:  The original idea was to support
alarm timers even if there was no rtc device, as long as the
system didn't go into suspend.

However, after further consideration, communicating to the application
that alarmtimers are not fully functional seems like the better
solution.

So this patch makes it so we return -ENOTSUPP to any posix _ALARM
clockid calls if there is no backing RTC device on the system.

Further this changes the behavior where when there is no rtc device
we will check for one on clock_getres, clock_gettime, timer_create,
and timer_nsleep instead of on suspend.

CC: Toralf Förster <toralf.foerster@gmx.de>
CC: Richard Weinberger <richard@nod.at
CC: Peter Zijlstra <peterz@infradead.org>
CC: Thomas Gleixner <tglx@linutronix.de>
Reported-by: NToralf Förster <toralf.foerster@gmx.de>
Reported by: Richard Weinberger <richard@nod.at>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The alarmtimers code currently picks a rtc device to use at
late init time. However, if your rtc driver is loaded as a module,
it may be registered after the alarmtimers late init code, leaving
the alarmtimers nonfunctional.

This patch moves the the rtcdevice selection to when we actually try
to use it, allowing us to make use of rtc modules that may have been
loaded at any point since bootup.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Meelis Roos <mroos@ut.ee>
Reported-by: NMeelis Roos <mroos@ut.ee>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NPeter Zijlstra <peterz@infradead.org>

class_find_device() takes a refcount on the rtc device. rtc_open()
takes another one, so we can drop it after the rtc_open() call.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>

alarmtimer_late_init() uses class_find_device() to find a alarm
capable rtc device. The match callback stores a pointer to the name in
the char pointer handed in from the call site. alarmtimer_late_init()
checks the char pointer for NULL, but the pointer is on the stack and
not initialized to NULL before the call. So it can have random content
when the match function did not identify a device, which leads to
random access in the following rtc_open() call where the pointer is
dereferenced

Instead of relying on the char pointer, check the return value of
class_find_device. If a device is found then the name pointer is valid
as well.
Reported-by: NIngo Molnar <mingo@elte.hu>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Ingo pointed out that the alarmtimers won't build if CONFIG_RTC_CLASS=n.
This patch adds proper ifdefs to the alarmtimer code to disable the rtc
usage if it is not built in.
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Thomas asked about the delayed irq work in the alarmtimers code,
and I realized that it was a legacy from when the alarmtimer base
lock was a mutex (due to concerns that we'd be interacting with
the RTC device, which is protected by mutexes).

Since the alarmtimer base is now protected by a spinlock, we can
simply execute alarmtimer functions directly from the hrtimer
callback. Should any future alarmtimer functions sleep, they can
simply manage scheduling any delayed work themselves.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This patch addresses a number of minor comment improvements and
other minor issues from Thomas' review of the alarmtimers code.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This patch exposes alarm-timers to userland via the posix clock
and timers interface, using two new clockids: CLOCK_REALTIME_ALARM
and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to
CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers
set against the _ALARM suffixed clockids will wake the system if
it is suspended.

Some background can be found here:
	https://lwn.net/Articles/429925/

The concept for Alarm-timers was inspired by the Android Alarm
driver (by Arve Hjønnevåg) found in the Android kernel tree.

See: http://android.git.kernel.org/?p=kernel/common.git;a=blob;f=drivers/rtc/alarm.c;h=1250edfbdf3302f5e4ea6194847c6ef4bb7beb1c;hb=android-2.6.36

While the in-kernel interface is pretty similar between
alarm-timers and Android alarm driver, the user-space interface
for the Android alarm driver is via ioctls to a new char device.
As mentioned above, I've instead chosen to export this functionality
via the posix interface, as it seemed a little simpler and avoids
creating duplicate interfaces to things like CLOCK_REALTIME and
CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and
ANDROID_ALARM_SYSTEMTIME).

The semantics of the Android alarm driver are different from what
this posix interface provides. For instance, threads other then
the thread waiting on the Android alarm driver are able to modify
the alarm being waited on. Also this interface does not allow
the same wakelock semantics that the Android driver provides
(ie: kernel takes a wakelock on RTC alarm-interupt, and holds it
through process wakeup, and while the process runs, until the
process either closes the char device or calls back in to wait
on a new alarm).

One potential way to implement similar semantics may be via
the timerfd infrastructure, but this needs more research.

There may also need to be some sort of sysfs system level policy
hooks that allow alarm timers to be disabled to keep them
from firing at inappropriate times (ie: laptop in a well insulated
bag, mid-flight).

CC: Arve Hjønnevåg <arve@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This provides the in kernel interface and infrastructure for
alarm-timers.

Alarm-timers are a hybrid style timer, similar to hrtimers,
but when the system is suspended, the RTC device is set to
fire and wake the system for when the soonest alarm-timer
expires.

The concept for Alarm-timers was inspired by the Android Alarm
driver (by Arve Hjønnevåg) found in the Android kernel tree.

See: http://android.git.kernel.org/?p=kernel/common.git;a=blob;f=drivers/rtc/alarm.c;h=1250edfbdf3302f5e4ea6194847c6ef4bb7beb1c;hb=android-2.6.36

This in-kernel interface should be fairly compatible with the
Android alarm driver in-kernel interface, but has the advantage
of utilizing the new RTC timerqueue code instead of doing direct
RTC manipulation.

CC: Arve Hjønnevåg <arve@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>