linux.git/kernel/time, branch v4.4.177

timekeeping: Use proper seqcount initializer

2019-02-20T09:13:08+00:00

[ Upstream commit ce10a5b3954f2514af726beb78ed8d7350c5e41c ]

tk_core.seq is initialized open coded, but that misses to initialize the
lockdep map when lockdep is enabled. Lockdep splats involving tk_core seq
consequently lack a name and are hard to read.

Use the proper initializer which takes care of the lockdep map
initialization.

[ tglx: Massaged changelog ]

Signed-off-by: Bart Van Assche 
Signed-off-by: Thomas Gleixner 
Cc: peterz@infradead.org
Cc: tj@kernel.org
Cc: johannes.berg@intel.com
Link: https://lkml.kernel.org/r/20181128234325.110011-12-bvanassche@acm.org
Signed-off-by: Sasha Levin

timer/debug: Change /proc/timer_list from 0444 to 0400

2018-12-21T13:09:49+00:00

[ Upstream commit 8e7df2b5b7f245c9bd11064712db5cb69044a362 ]

While it uses %pK, there's still few reasons to read this file
as non-root.

Suggested-by: Linus Torvalds 
Acked-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

posix-timers: Sanitize overrun handling

2018-12-17T20:55:15+00:00

commit 78c9c4dfbf8c04883941445a195276bb4bb92c76 upstream.

The posix timer overrun handling is broken because the forwarding functions
can return a huge number of overruns which does not fit in an int. As a
consequence timer_getoverrun(2) and siginfo::si_overrun can turn into
random number generators.

The k_clock::timer_forward() callbacks return a 64 bit value now. Make
k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal
accounting is correct. 3Remove the temporary (int) casts.

Add a helper function which clamps the overrun value returned to user space
via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value
between 0 and INT_MAX. INT_MAX is an indicator for user space that the
overrun value has been clamped.

Reported-by: Team OWL337 
Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Cc: Peter Zijlstra 
Cc: Michael Kerrisk 
Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
[florian: Make patch apply to v4.9.135]
Signed-off-by: Florian Fainelli 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Sasha Levin 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

alarmtimer: Prevent overflow for relative nanosleep

2018-10-10T06:52:05+00:00

[ Upstream commit 5f936e19cc0ef97dbe3a56e9498922ad5ba1edef ]

Air Icy reported:

  UBSAN: Undefined behaviour in kernel/time/alarmtimer.c:811:7
  signed integer overflow:
  1529859276030040771 + 9223372036854775807 cannot be represented in type 'long long int'
  Call Trace:
   alarm_timer_nsleep+0x44c/0x510 kernel/time/alarmtimer.c:811
   __do_sys_clock_nanosleep kernel/time/posix-timers.c:1235 [inline]
   __se_sys_clock_nanosleep kernel/time/posix-timers.c:1213 [inline]
   __x64_sys_clock_nanosleep+0x326/0x4e0 kernel/time/posix-timers.c:1213
   do_syscall_64+0xb8/0x3a0 arch/x86/entry/common.c:290

alarm_timer_nsleep() uses ktime_add() to add the current time and the
relative expiry value. ktime_add() has no sanity checks so the addition
can overflow when the relative timeout is large enough.

Use ktime_add_safe() which has the necessary sanity checks in place and
limits the result to the valid range.

Fixes: 9a7adcf5c6de ("timers: Posix interface for alarm-timers")
Reported-by: Team OWL337 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1807020926360.1595@nanos.tec.linutronix.de
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

nohz: Fix local_timer_softirq_pending()

2018-08-09T10:19:27+00:00

commit 80d20d35af1edd632a5e7a3b9c0ab7ceff92769e upstream.

local_timer_softirq_pending() checks whether the timer softirq is
pending with: local_softirq_pending() & TIMER_SOFTIRQ.

This is wrong because TIMER_SOFTIRQ is the softirq number and not a
bitmask. So the test checks for the wrong bit.

Use BIT(TIMER_SOFTIRQ) instead.

Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
Signed-off-by: Anna-Maria Gleixner 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Paul E. McKenney 
Reviewed-by: Daniel Bristot de Oliveira 
Acked-by: Frederic Weisbecker 
Cc: bigeasy@linutronix.de
Cc: peterz@infradead.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180731161358.29472-1-anna-maria@linutronix.de
Signed-off-by: Greg Kroah-Hartman

time: Make sure jiffies_to_msecs() preserves non-zero time periods

2018-07-03T09:21:30+00:00

commit abcbcb80cd09cd40f2089d912764e315459b71f7 upstream.

For the common cases where 1000 is a multiple of HZ, or HZ is a multiple of
1000, jiffies_to_msecs() never returns zero when passed a non-zero time
period.

However, if HZ > 1000 and not an integer multiple of 1000 (e.g. 1024 or
1200, as used on alpha and DECstation), jiffies_to_msecs() may return zero
for small non-zero time periods.  This may break code that relies on
receiving back a non-zero value.

jiffies_to_usecs() does not need such a fix: one jiffy can only be less
than one µs if HZ > 1000000, and such large values of HZ are already
rejected at build time, twice:

  - include/linux/jiffies.h does #error if HZ >= 12288,
  - kernel/time/time.c has BUILD_BUG_ON(HZ > USEC_PER_SEC).

Broken since forever.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Arnd Bergmann 
Cc: John Stultz 
Cc: Stephen Boyd 
Cc: linux-alpha@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180622143357.7495-1-geert@linux-m68k.org
Signed-off-by: Greg Kroah-Hartman

time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting

2018-05-26T06:49:00+00:00

commit 3d88d56c5873f6eebe23e05c3da701960146b801 upstream.

Due to how the MONOTONIC_RAW accumulation logic was handled,
there is the potential for a 1ns discontinuity when we do
accumulations. This small discontinuity has for the most part
gone un-noticed, but since ARM64 enabled CLOCK_MONOTONIC_RAW
in their vDSO clock_gettime implementation, we've seen failures
with the inconsistency-check test in kselftest.

This patch addresses the issue by using the same sub-ns
accumulation handling that CLOCK_MONOTONIC uses, which avoids
the issue for in-kernel users.

Since the ARM64 vDSO implementation has its own clock_gettime
calculation logic, this patch reduces the frequency of errors,
but failures are still seen. The ARM64 vDSO will need to be
updated to include the sub-nanosecond xtime_nsec values in its
calculation for this issue to be completely fixed.

Signed-off-by: John Stultz 
Tested-by: Daniel Mentz 
Cc: Prarit Bhargava 
Cc: Kevin Brodsky 
Cc: Richard Cochran 
Cc: Stephen Boyd 
Cc: Will Deacon 
Cc: "stable #4 . 8+" 
Cc: Miroslav Lichvar 
Link: http://lkml.kernel.org/r/1496965462-20003-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner 
[fabrizio: cherry-pick to 4.4. Kept cycle_t type for function
logarithmic_accumulation local variable "interval". Dropped
casting of "interval" variable]
Signed-off-by: Fabrizio Castro 
Signed-off-by: Biju Das 
Signed-off-by: Greg Kroah-Hartman

tick/broadcast: Use for_each_cpu() specially on UP kernels

2018-05-26T06:48:56+00:00

commit 5596fe34495cf0f645f417eb928ef224df3e3cb4 upstream.

for_each_cpu() unintuitively reports CPU0 as set independent of the actual
cpumask content on UP kernels. This causes an unexpected PIT interrupt
storm on a UP kernel running in an SMP virtual machine on Hyper-V, and as
a result, the virtual machine can suffer from a strange random delay of 1~20
minutes during boot-up, and sometimes it can hang forever.

Protect if by checking whether the cpumask is empty before entering the
for_each_cpu() loop.

[ tglx: Use !IS_ENABLED(CONFIG_SMP) instead of #ifdeffery ]

Signed-off-by: Dexuan Cui 
Signed-off-by: Thomas Gleixner 
Cc: Josh Poulson 
Cc: "Michael Kelley (EOSG)" 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Cc: stable@vger.kernel.org
Cc: Rakib Mullick 
Cc: Jork Loeser 
Cc: Greg Kroah-Hartman 
Cc: Andrew Morton 
Cc: KY Srinivasan 
Cc: Linus Torvalds 
Cc: Alexey Dobriyan 
Cc: Dmitry Vyukov 
Link: https://lkml.kernel.org/r/KL1P15301MB000678289FE55BA365B3279ABF990@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM
Link: https://lkml.kernel.org/r/KL1P15301MB0006FA63BC22BEB64902EAA0BF930@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM
Signed-off-by: Greg Kroah-Hartman

time: Change posix clocks ops interfaces to use timespec64

2018-03-24T09:58:40+00:00

[ Upstream commit d340266e19ddb70dbd608f9deedcfb35fdb9d419 ]

struct timespec is not y2038 safe on 32 bit machines.

The posix clocks apis use struct timespec directly and through struct
itimerspec.

Replace the posix clock interfaces to use struct timespec64 and struct
itimerspec64 instead.  Also fix up their implementations accordingly.

Note that the clock_getres() interface has also been changed to use
timespec64 even though this particular interface is not affected by the
y2038 problem. This helps verification for internal kernel code for y2038
readiness by getting rid of time_t/ timeval/ timespec.

Signed-off-by: Deepa Dinamani 
Cc: arnd@arndb.de
Cc: y2038@lists.linaro.org
Cc: netdev@vger.kernel.org
Cc: Richard Cochran 
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/1490555058-4603-3-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

sysrq: Reset the watchdog timers while displaying high-resolution timers

2018-03-22T08:23:21+00:00

[ Upstream commit 0107042768658fea9f5f5a9c00b1c90f5dab6a06 ]

On systems with a large number of CPUs, running sysrq- can cause
watchdog timeouts.  There are two slow sections of code in the sysrq-
path in timer_list.c.

1. print_active_timers() - This function is called by print_cpu() and
   contains a slow goto loop.  On a machine with hundreds of CPUs, this
   loop took approximately 100ms for the first CPU in a NUMA node.
   (Subsequent CPUs in the same node ran much quicker.)  The total time
   to print all of the CPUs is ultimately long enough to trigger the
   soft lockup watchdog.

2. print_tickdevice() - This function outputs a large amount of textual
   information.  This function also took approximately 100ms per CPU.

Since sysrq- is not a performance critical path, there should be no
harm in touching the nmi watchdog in both slow sections above.  Touching
it in just one location was insufficient on systems with hundreds of
CPUs as occasional timeouts were still observed during testing.

This issue was observed on an Oracle T7 machine with 128 CPUs, but I
anticipate it may affect other systems with similarly large numbers of
CPUs.

Signed-off-by: Tom Hromatka 
Reviewed-by: Rob Gardner 
Signed-off-by: John Stultz 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman