linux-toradex.git/kernel/time/sched_clock.c, branch v5.10-rc1

time/sched_clock: Use seqcount_latch_t

2020-09-10T09:19:29+00:00

Latch sequence counters have unique read and write APIs, and thus
seqcount_latch_t was recently introduced at seqlock.h.

Use that new data type instead of plain seqcount_t. This adds the
necessary type-safety and ensures only latching-safe seqcount APIs are
to be used.

Signed-off-by: Ahmed S. Darwish 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200827114044.11173-5-a.darwish@linutronix.de

time/sched_clock: Use raw_read_seqcount_latch() during suspend

2020-09-10T09:19:28+00:00

sched_clock uses seqcount_t latching to switch between two storage
places protected by the sequence counter. This allows it to have
interruptible, NMI-safe, seqcount_t write side critical sections.

Since 7fc26327b756 ("seqlock: Introduce raw_read_seqcount_latch()"),
raw_read_seqcount_latch() became the standardized way for seqcount_t
latch read paths. Due to the dependent load, it has one read memory
barrier less than the currently used raw_read_seqcount() API.

Use raw_read_seqcount_latch() for the suspend path.

Commit aadd6e5caaac ("time/sched_clock: Use raw_read_seqcount_latch()")
missed changing that instance of raw_read_seqcount().

References: 1809bfa44e10 ("timers, sched/clock: Avoid deadlock during read from NMI")
Signed-off-by: Ahmed S. Darwish 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200715092345.GA231464@debian-buster-darwi.lab.linutronix.de

time: Delete repeated words in comments

2020-08-10T20:14:07+00:00

Drop repeated words in kernel/time/.  {when, one, into}

Signed-off-by: Randy Dunlap 
Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Link: https://lore.kernel.org/r/20200807033248.8452-1-rdunlap@infradead.org

time/sched_clock: Use raw_read_seqcount_latch()

2020-07-20T10:50:47+00:00

sched_clock uses seqcount_t latching to switch between two storage
places protected by the sequence counter. This allows it to have
interruptible, NMI-safe, seqcount_t write side critical sections.

Since 7fc26327b756 ("seqlock: Introduce raw_read_seqcount_latch()"),
raw_read_seqcount_latch() became the standardized way for seqcount_t
latch read paths. Due to the dependent load, it also has one read
memory barrier less than the currently used raw_read_seqcount() API.

Use raw_read_seqcount_latch() for the seqcount_t latch read path.

Signed-off-by: Ahmed S. Darwish 
Signed-off-by: Leo Yan 
Link: https://lkml.kernel.org/r/20200625085745.GD117543@hirez.programming.kicks-ass.net
Link: https://lkml.kernel.org/r/20200715092345.GA231464@debian-buster-darwi.lab.linutronix.de
Link: https://lore.kernel.org/r/20200716051130.4359-3-leo.yan@linaro.org
References: 1809bfa44e10 ("timers, sched/clock: Avoid deadlock during read from NMI")
Signed-off-by: Will Deacon

sched_clock: Expose struct clock_read_data

2020-07-20T10:50:47+00:00

In order to support perf_event_mmap_page::cap_time features, an
architecture needs, aside from a userspace readable counter register,
to expose the exact clock data so that userspace can convert the
counter register into a correct timestamp.

Provide struct clock_read_data and two (seqcount) helpers so that
architectures (arm64 in specific) can expose the numbers to userspace.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Leo Yan 
Link: https://lore.kernel.org/r/20200716051130.4359-2-leo.yan@linaro.org
Signed-off-by: Will Deacon

time/sched_clock: Expire timer in hardirq context

2020-03-19T08:45:08+00:00

To minimize latency, PREEMPT_RT kernels expires hrtimers in preemptible
softirq context by default. This can be overriden by marking the timer's
expiry with HRTIMER_MODE_HARD.

sched_clock_timer is missing this annotation: if its callback is preempted
and the duration of the preemption exceeds the wrap around time of the
underlying clocksource, sched clock will get out of sync.

Mark the sched_clock_timer for expiry in hard interrupt context.

Signed-off-by: Ahmed S. Darwish 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20200309181529.26558-1-a.darwish@linutronix.de

time/sched_clock: Disable interrupts in sched_clock_register()

2020-01-09T17:50:18+00:00

Instead of issueing a warning if sched_clock_register() is called from a
context where IRQs are enabled, the code now ensures that IRQs are indeed
disabled.

Signed-off-by: Paul Cercueil 
Signed-off-by: Thomas Gleixner 
Acked-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/20200107010630.954648-1-paul@crapouillou.net

timers/sched_clock: Include local timekeeping.h for missing declarations

2019-10-23T12:48:23+00:00

Include the timekeeping.h header to get the declaration of the
sched_clock_{suspend,resume} functions. Fixes the following sparse
warnings:

kernel/time/sched_clock.c:275:5: warning: symbol 'sched_clock_suspend' was not declared. Should it be static?
kernel/time/sched_clock.c:286:6: warning: symbol 'sched_clock_resume' was not declared. Should it be static?

Signed-off-by: Ben Dooks (Codethink) 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20191022131226.11465-1-ben.dooks@codethink.co.uk

Merge tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

2019-05-07T16:18:12+00:00

Pull printk updates from Petr Mladek:

 - Allow state reset of printk_once() calls.

 - Prevent crashes when dereferencing invalid pointers in vsprintf().
   Only the first byte is checked for simplicity.

 - Make vsprintf warnings consistent and inlined.

 - Treewide conversion of obsolete %pf, %pF to %ps, %pF printf
   modifiers.

 - Some clean up of vsprintf and test_printf code.

* tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  lib/vsprintf: Make function pointer_string static
  vsprintf: Limit the length of inlined error messages
  vsprintf: Avoid confusion between invalid address and value
  vsprintf: Prevent crash when dereferencing invalid pointers
  vsprintf: Consolidate handling of unknown pointer specifiers
  vsprintf: Factor out %pO handler as kobject_string()
  vsprintf: Factor out %pV handler as va_format()
  vsprintf: Factor out %p[iI] handler as ip_addr_string()
  vsprintf: Do not check address of well-known strings
  vsprintf: Consistent %pK handling for kptr_restrict == 0
  vsprintf: Shuffle restricted_pointer()
  printk: Tie printk_once / printk_deferred_once into .data.once for reset
  treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively
  lib/test_printf: Switch to bitmap_zalloc()

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-05-06T21:50:46+00:00

Pull timer updates from Ingo Molnar:
 "This cycle had the following changes:

   - Timer tracing improvements (Anna-Maria Gleixner)

   - Continued tasklet reduction work: remove the hrtimer_tasklet
     (Thomas Gleixner)

   - Fix CPU hotplug remove race in the tick-broadcast mask handling
     code (Thomas Gleixner)

   - Force upper bound for setting CLOCK_REALTIME, to fix ABI
     inconsistencies with handling values that are close to the maximum
     supported and the vagueness of when uptime related wraparound might
     occur. Make the consistent maximum the year 2232 across all
     relevant ABIs and APIs. (Thomas Gleixner)

   - various cleanups and smaller fixes"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick: Fix typos in comments
  tick/broadcast: Fix warning about undefined tick_broadcast_oneshot_offline()
  timekeeping: Force upper bound for setting CLOCK_REALTIME
  timer/trace: Improve timer tracing
  timer/trace: Replace deprecated vsprintf pointer extension %pf by %ps
  timer: Move trace point to get proper index
  tick/sched: Update tick_sched struct documentation
  tick: Remove outgoing CPU from broadcast masks
  timekeeping: Consistently use unsigned int for seqcount snapshot
  softirq: Remove tasklet_hrtimer
  xfrm: Replace hrtimer tasklet with softirq hrtimer
  mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer