11 Aug, 2011
1 commit
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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
CC: stable@kernel.org
Signed-off-by: John Stultz
10 Aug, 2011
2 commits
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Following common_timer_get, zero out the itimerspec passed in.
CC: Thomas Gleixner
CC: stable@kernel.org
Signed-off-by: John Stultz -
We don't check if old_setting is non null before assigning it, so
correct this.CC: Thomas Gleixner
CC: stable@kernel.org
Signed-off-by: John Stultz
23 Jul, 2011
1 commit
-
…l/git/tip/linux-2.6-tip
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
time: Fix stupid KERN_WARN compile issue
rtc: Avoid accumulating time drift in suspend/resume
time: Avoid accumulating time drift in suspend/resume
time: Catch invalid timespec sleep values in __timekeeping_inject_sleeptime
21 Jul, 2011
1 commit
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Terribly embarassing. Don't know how I committed this, but its
KERN_WARNING not KERN_WARN.This fixes the following compile error:
kernel/time/timekeeping.c: In function ‘__timekeeping_inject_sleeptime’:
kernel/time/timekeeping.c:608: error: ‘KERN_WARN’ undeclared (first use in this function)
kernel/time/timekeeping.c:608: error: (Each undeclared identifier is reported only once
kernel/time/timekeeping.c:608: error: for each function it appears in.)
kernel/time/timekeeping.c:608: error: expected ‘)’ before string constant
make[2]: *** [kernel/time/timekeeping.o] Error 1Reported-by: Ingo Molnar
Signed-off-by: John Stultz
22 Jun, 2011
4 commits
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Because the read_persistent_clock interface is usually backed by
only a second granular interface, each time we read from the persistent
clock for suspend/resume, we introduce a half second (on average) of error.In order to avoid this error accumulating as the system is suspended
over and over, this patch measures the time delta between the persistent
clock and the system CLOCK_REALTIME.If the delta is less then 2 seconds from the last suspend, we compensate
by using the previous time delta (keeping it close). If it is larger
then 2 seconds, we assume the clock was set or has been changed, so we
do no correction and update the delta.Note: If NTP is running, ths could seem to "fight" with the NTP corrected
time, where as if the system time was off by 1 second, and NTP slewed the
value in, a suspend/resume cycle could undo this correction, by trying to
restore the previous offset from the persistent clock. However, without
this patch, since each read could cause almost a full second worth of
error, its possible to get almost 2 seconds of error just from the
suspend/resume cycle alone, so this about equal to any offset added by
the compensation.Further on systems that suspend/resume frequently, this should keep time
closer then NTP could compensate for if the errors were allowed to
accumulate.Credits to Arve Hjønnevåg for suggesting this solution.
CC: Arve Hjønnevåg
CC: Thomas Gleixner
Signed-off-by: John Stultz -
Arve suggested making sure we catch possible negative sleep time
intervals that could be passed into timekeeping_inject_sleeptime.CC: Arve Hjønnevåg
CC: Thomas Gleixner
Signed-off-by: John Stultz -
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
CC: Richard Weinberger
CC: Thomas Gleixner
Reported-by: Toralf Förster
Reported by: Richard Weinberger
Signed-off-by: John Stultz -
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
CC: Meelis Roos
Reported-by: Meelis Roos
Signed-off-by: John Stultz
17 Jun, 2011
1 commit
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The clocksource watchdog code is interruptible and it has been
observed that this can trigger false positives which disable the TSC.The reason is that an interrupt storm or a long running interrupt
handler between the read of the watchdog source and the read of the
TSC brings the two far enough apart that the delta is larger than the
unstable treshold. Move both reads into a short interrupt disabled
region to avoid that.Reported-and-tested-by: Vernon Mauery
Signed-off-by: Thomas Gleixner
Cc: stable@kernel.org
03 Jun, 2011
1 commit
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For UP it's stupid to request an initialized cpumask for the clock
event devices. Though we need the mask set even on UP to avoid a
horrible ifdeffery especially in the broadcast code.For SMP we can at least try to survive with a warning and set the
cpumask of the cpu we're running on. That gives a decent chance to
bring the machine up and retrieve the debug info.Signed-off-by: Thomas Gleixner
Cc: Linus Walleij
Cc: Russell King - ARM Linux
Cc: Stephen Boyd
23 May, 2011
1 commit
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Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.Signed-off-by: Thomas Gleixner
Reviewed-by: Peter Zijlstra
21 May, 2011
1 commit
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Reason: Get upstream fixes and kfree_rcu which is necessary for a
follow up patch.Signed-off-by: Thomas Gleixner
20 May, 2011
3 commits
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unsigned long is not 64bit on 32bit machine.
Signed-off-by: Thomas Gleixner
-
…l/git/tip/linux-2.6-tip
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
hrtimer: Make lookup table const
RTC: Disable CONFIG_RTC_CLASS from being built as a module
timers: Fix alarmtimer build issues when CONFIG_RTC_CLASS=n
timers: Remove delayed irqwork from alarmtimers implementation
timers: Improve alarmtimer comments and minor fixes
timers: Posix interface for alarm-timers
timers: Introduce in-kernel alarm-timer interface
timers: Add rb_init_node() to allow for stack allocated rb nodes
time: Add timekeeping_inject_sleeptime -
…x/kernel/git/tip/linux-2.6-tip
* 'timers-clockevents-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: hpet: Cleanup the clockevents init and register code
x86: Convert PIT to clockevents_config_and_register()
clockevents: Provide interface to reconfigure an active clock event device
clockevents: Provide combined configure and register function
clockevents: Restructure clock_event_device members
clocksource: Get rid of the hardcoded 5 seconds sleep time limit
clocksource: Restructure clocksource struct members
19 May, 2011
3 commits
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Some ARM SoCs have clock event devices which have their frequency
modified due to frequency scaling. Provide an interface which allows
to reconfigure an active device. After reconfiguration reprogram the
current pending event.Signed-off-by: Thomas Gleixner
Cc: LAK
Cc: John Stultz
Acked-by: Linus Walleij
Reviewed-by: Ingo Molnar
Link: http://lkml.kernel.org/r/%3C20110518210136.437459958%40linutronix.de%3E -
All clockevent devices have the same open coded initialization
functions. Provide an interface which does all necessary
initialization in the core code.Signed-off-by: Thomas Gleixner
Cc: John Stultz
Reviewed-by: Ingo Molnar
Link: http://lkml.kernel.org/r/%3C20110518210136.331975870%40linutronix.de%3E -
Slow clocksources can have a way longer sleep time than 5 seconds and
even fast ones can easily cope with 600 seconds and still maintain
proper accuracy.Signed-off-by: Thomas Gleixner
Cc: John Stultz
Reviewed-by: Ingo Molnar
Link: http://lkml.kernel.org/r/%3C20110518210136.109811585%40linutronix.de%3E
17 May, 2011
1 commit
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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
Cc: John Stultz
Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1105161105170.3078%40ionos%3E
Cc: stable@kernel.org
Signed-off-by: Thomas Gleixner
05 May, 2011
2 commits
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Avoid taking broadcast_lock in the idle path for systems where the
timer doesn't stop in C3.[ tglx: Removed the stale label and added comment ]
Signed-off-by: Andi Kleen
Cc: Dave Kleikamp
Cc: Chris Mason
Cc: Peter Zijlstra
Cc: Tim Chen
Cc: lenb@kernel.org
Cc: paulmck@us.ibm.com
Link: http://lkml.kernel.org/r/%3C20110504234806.GF2925%40one.firstfloor.org%3E
Signed-off-by: Thomas Gleixner -
Christian Hoffmann reported that the command line clocksource override
with acpi_pm timer fails:Kernel command line: clocksource=acpi_pm
hpet clockevent registered
Switching to clocksource hpet
Override clocksource acpi_pm is not HRT compatible.
Cannot switch while in HRT/NOHZ mode.The watchdog code is what enables CLOCK_SOURCE_VALID_FOR_HRES, but we
actually end up selecting the clocksource before we enqueue it into
the watchdog list, so that's why we see the warning and fail to switch
to acpi_pm timer as requested. That's particularly bad when we want to
debug timekeeping related problems in early boot.Put the selection call last.
Reported-by: Christian Hoffmann
Signed-off-by: John Stultz
Cc: stable@kernel.org # 32...
Link: http://lkml.kernel.org/r/%3C1304558210.2943.24.camel%40work-vm%3E
Signed-off-by: Thomas Gleixner
04 May, 2011
2 commits
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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: Thomas Gleixner
Cc: John Stultz -
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
dereferencedInstead 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: Ingo Molnar
Cc: John Stultz
Signed-off-by: Thomas Gleixner
03 May, 2011
3 commits
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Some applications must be aware of clock realtime being set
backward. A simple example is a clock applet which arms a timer for
the next minute display. If clock realtime is set backward then the
applet displays a stale time for the amount of time which the clock
was set backwards. Due to that applications poll the time because we
don't have an interface.Extend the timerfd interface by adding a flag which puts the timer
onto a different internal realtime clock. All timers on this clock are
expired whenever the clock was set.The timerfd core records the monotonic offset when the timer is
created. When the timer is armed, then the current offset is compared
to the previous recorded offset. When it has changed, then
timerfd_settime returns -ECANCELED. When a timer is read the offset is
compared and if it changed -ECANCELED returned to user space. Periodic
timers are not rearmed in the cancelation case.Signed-off-by: Thomas Gleixner
Acked-by: John Stultz
Cc: Chris Friesen
Tested-by: Kay Sievers
Cc: "Kirill A. Shutemov"
Cc: Peter Zijlstra
Cc: Davide Libenzi
Reviewed-by: Alexander Shishkin
Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1104271359580.3323%40ionos%3E
Signed-off-by: Thomas Gleixner -
Make clock_was_set() unconditional and rename hres_timers_resume to
hrtimers_resume. This is a preparatory patch for hrtimers which are
cancelled when clock realtime was set.Signed-off-by: Thomas Gleixner
-
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: Ingo Molnar
Signed-off-by: John Stultz
Signed-off-by: Thomas Gleixner
29 Apr, 2011
2 commits
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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
Signed-off-by: John Stultz -
This patch addresses a number of minor comment improvements and
other minor issues from Thomas' review of the alarmtimers code.CC: Thomas Gleixner
Signed-off-by: John Stultz
27 Apr, 2011
3 commits
-
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
CC: Thomas Gleixner
CC: Alessandro Zummo
Acked-by: Arnd Bergmann
Signed-off-by: John Stultz -
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
CC: Thomas Gleixner
CC: Alessandro Zummo
Acked-by: Arnd Bergmann
Signed-off-by: John Stultz -
Some platforms cannot implement read_persistent_clock, as
their RTC devices are only accessible when interrupts are enabled.
This keeps them from being used by the timekeeping code on resume
to measure the time in suspend.The RTC layer tries to work around this, by calling do_settimeofday
on resume after irqs are reenabled to set the time properly. However,
this only corrects CLOCK_REALTIME, and does not properly adjust
the sleep time value. This causes btime in /proc/stat to be incorrect
as well as making the new CLOCK_BOTTTIME inaccurate.This patch resolves the issue by introducing a new timekeeping hook
to allow the RTC layer to inject the sleep time on resume.The code also checks to make sure that read_persistent_clock is
nonfunctional before setting the sleep time, so that should the RTC's
HCTOSYS option be configured in on a system that does support
read_persistent_clock we will not increase the total_sleep_time twice.CC: Arve Hjønnevåg
CC: Thomas Gleixner
Acked-by: Arnd Bergmann
Signed-off-by: John Stultz
18 Apr, 2011
1 commit
-
A dynamic posix clock is protected from asynchronous removal by a mutex.
However, using a mutex has the unwanted effect that a long running clock
operation in one process will unnecessarily block other processes.For example, one process might call read() to get an external time stamp
coming in at one pulse per second. A second process calling clock_gettime
would have to wait for almost a whole second.This patch fixes the issue by using a reader/writer semaphore instead of
a mutex.Signed-off-by: Richard Cochran
Cc: John Stultz
Link: http://lkml.kernel.org/r/%3C20110330132421.GA31771%40riccoc20.at.omicron.at%3E
Signed-off-by: Thomas Gleixner
08 Apr, 2011
1 commit
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* 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6:
Fix common misspellings
04 Apr, 2011
1 commit
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The ADJ_SETOFFSET bit added in commit 094aa188 ("ntp: Add ADJ_SETOFFSET
mode bit") also introduced a way for any user to change the system time.
Sneaky or buggy calls to adjtimex() could setADJ_OFFSET_SS_READ | ADJ_SETOFFSET
which would result in a successful call to timekeeping_inject_offset().
This patch fixes the issue by adding the capability check.Signed-off-by: Richard Cochran
Signed-off-by: Linus Torvalds
31 Mar, 2011
1 commit
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Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi
24 Mar, 2011
1 commit
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The timekeeping subsystem uses a sysdev class and a sysdev for
executing timekeeping_suspend() after interrupts have been turned off
on the boot CPU (during system suspend) and for executing
timekeeping_resume() before turning on interrupts on the boot CPU
(during system resume). However, since both of these functions
ignore their arguments, the entire mechanism may be replaced with a
struct syscore_ops object which is simpler.Signed-off-by: Rafael J. Wysocki
Reviewed-by: Thomas Gleixner
16 Mar, 2011
1 commit
-
…l/git/tip/linux-2.6-tip
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (62 commits)
posix-clocks: Check write permissions in posix syscalls
hrtimer: Remove empty hrtimer_init_hres_timer()
hrtimer: Update hrtimer->state documentation
hrtimer: Update base[CLOCK_BOOTTIME].offset correctly
timers: Export CLOCK_BOOTTIME via the posix timers interface
timers: Add CLOCK_BOOTTIME hrtimer base
time: Extend get_xtime_and_monotonic_offset() to also return sleep
time: Introduce get_monotonic_boottime and ktime_get_boottime
hrtimers: extend hrtimer base code to handle more then 2 clockids
ntp: Remove redundant and incorrect parameter check
mn10300: Switch do_timer() to xtimer_update()
posix clocks: Introduce dynamic clocks
posix-timers: Cleanup namespace
posix-timers: Add support for fd based clocks
x86: Add clock_adjtime for x86
posix-timers: Introduce a syscall for clock tuning.
time: Splitout compat timex accessors
ntp: Add ADJ_SETOFFSET mode bit
time: Introduce timekeeping_inject_offset
posix-timer: Update comment
...Fix up new system-call-related conflicts in
arch/x86/ia32/ia32entry.S
arch/x86/include/asm/unistd_32.h
arch/x86/include/asm/unistd_64.h
arch/x86/kernel/syscall_table_32.S
(name_to_handle_at()/open_by_handle_at() vs clock_adjtime()), and some
due to movement of get_jiffies_64() in:
kernel/time.c
13 Mar, 2011
1 commit
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pc_clock_settime() and pc_clock_adjtime() do not check whether the fd
was opened in write mode, so a clock can be set with a read only fd.[ tglx: We deliberately do not return -EPERM as we want this to be
distingushable from the capability based permission check ]Signed-off-by: Torben Hohn
LKML-Reference:
Cc: Richard Cochran
Cc: John Stultz
Cc: Thomas Gleixner
26 Feb, 2011
1 commit
-
When the per cpu timer is marked CLOCK_EVT_FEAT_C3STOP, then we only
can switch into oneshot mode, when the backup broadcast device
supports oneshot mode as well. Otherwise we would try to switch the
broadcast device into an unsupported mode unconditionally. This went
unnoticed so far as the current available broadcast devices support
oneshot mode. Seth unearthed this problem while debugging and working
around an hpet related BIOS wreckage.Add the necessary check to tick_is_oneshot_available().
Reported-and-tested-by: Seth Forshee
Signed-off-by: Thomas Gleixner
LKML-Reference:
Cc: stable@kernel.org # .21 ->