linux-toradex.git/include/linux/cpumask.h, branch v4.11-rc3

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

2017-02-20T18:06:32+00:00

Pull timer updates from Thomas Gleixner:
 "Nothing exciting, just the usual pile of fixes, updates and cleanups:

   - A bunch of clocksource driver updates

   - Removal of CONFIG_TIMER_STATS and the related /proc file

   - More posix timer slim down work

   - A scalability enhancement in the tick broadcast code

   - Math cleanups"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  hrtimer: Catch invalid clockids again
  math64, tile: Fix build failure
  clocksource/drivers/arm_arch_timer:: Mark cyclecounter __ro_after_init
  timerfd: Protect the might cancel mechanism proper
  timer_list: Remove useless cast when printing
  time: Remove CONFIG_TIMER_STATS
  clocksource/drivers/arm_arch_timer: Work around Hisilicon erratum 161010101
  clocksource/drivers/arm_arch_timer: Introduce generic errata handling infrastructure
  clocksource/drivers/arm_arch_timer: Remove fsl-a008585 parameter
  clocksource/drivers/arm_arch_timer: Add dt binding for hisilicon-161010101 erratum
  clocksource/drivers/ostm: Add renesas-ostm timer driver
  clocksource/drivers/ostm: Document renesas-ostm timer DT bindings
  clocksource/drivers/tcb_clksrc: Use 32 bit tcb as sched_clock
  clocksource/drivers/gemini: Add driver for the Cortina Gemini
  clocksource: add DT bindings for Cortina Gemini
  clockevents: Add a clkevt-of mechanism like clksrc-of
  tick/broadcast: Reduce lock cacheline contention
  timers: Omit POSIX timer stuff from task_struct when disabled
  x86/timer: Make delay() work during early bootup
  delay: Add explanation of udelay() inaccuracy
  ...

cpumask: use nr_cpumask_bits for parsing functions

2017-02-08T23:41:43+00:00

Commit 513e3d2d11c9 ("cpumask: always use nr_cpu_ids in formatting and
parsing functions") converted both cpumask printing and parsing
functions to use nr_cpu_ids instead of nr_cpumask_bits.  While this was
okay for the printing functions as it just picked one of the two output
formats that we were alternating between depending on a kernel config,
doing the same for parsing wasn't okay.

nr_cpumask_bits can be either nr_cpu_ids or NR_CPUS.  We can always use
nr_cpu_ids but that is a variable while NR_CPUS is a constant, so it can
be more efficient to use NR_CPUS when we can get away with it.
Converting the printing functions to nr_cpu_ids makes sense because it
affects how the masks get presented to userspace and doesn't break
anything; however, using nr_cpu_ids for parsing functions can
incorrectly leave the higher bits uninitialized while reading in these
masks from userland.  As all testing and comparison functions use
nr_cpumask_bits which can be larger than nr_cpu_ids, the parsed cpumasks
can erroneously yield false negative results.

This made the taskstats interface incorrectly return -EINVAL even when
the inputs were correct.

Fix it by restoring the parse functions to use nr_cpumask_bits instead
of nr_cpu_ids.

Link: http://lkml.kernel.org/r/20170206182442.GB31078@htj.duckdns.org
Fixes: 513e3d2d11c9 ("cpumask: always use nr_cpu_ids in formatting and parsing functions")
Signed-off-by: Tejun Heo 
Reported-by: Martin Steigerwald 
Debugged-by: Ben Hutchings 
Cc: 	[4.0+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

tick/broadcast: Reduce lock cacheline contention

2017-02-04T07:54:46+00:00

It was observed that on an Intel x86 system without the ARAT (Always
running APIC timer) feature and with fairly large number of CPUs as
well as CPUs coming in and out of intel_idle frequently, the lock
contention on the tick_broadcast_lock can become significant.

To reduce contention, the lock is put into its own cacheline and all
the cpumask_var_t variables are put into the __read_mostly section.

Running the SP benchmark of the NAS Parallel Benchmarks on a 4-socket
16-core 32-thread Nehalam system, the performance number improved
from 3353.94 Mop/s to 3469.31 Mop/s when this patch was applied on
a 4.9.6 kernel.  This is a 3.4% improvement.

Signed-off-by: Waiman Long 
Cc: "Peter Zijlstra (Intel)" 
Cc: Andrew Morton 
Link: http://lkml.kernel.org/r/1485799063-20857-1-git-send-email-longman@redhat.com
Signed-off-by: Thomas Gleixner

x86/smpboot: Prevent false positive out of bounds cpumask access warning

2016-12-15T10:32:31+00:00

prefill_possible_map() reinitializes the cpu_possible_map by setting the
possible cpu bits and clearing all other bits up to NR_CPUS.

This is technically always correct because cpu_possible_map is statically
allocated and sized NR_CPUS. With CPUMASK_OFFSTACK and DEBUG_PER_CPU_MAPS
enabled the bounds check of cpu masks happens on nr_cpu_ids. nr_cpu_ids is
initialized to NR_CPUS and only limited after the set/clear bit loops have
been executed. 

But if the system was booted with "nr_cpus=N" on the command line, where N
is < NR_CPUS then nr_cpu_ids is limited in the parameter parsing function
before prefill_possible_map() is invoked. As a consequence the cpumask
bounds check triggers when clearing the bits past nr_cpu_ids.

Add a helper which allows to reset cpu_possible_map w/o the bounds check
and then set only the possible bits which are well inside bounds.

Reported-by: Dmitry Safonov 
Cc: Rusty Russell 
Cc: 0x7f454c46@gmail.com
Cc: Jan Beulich 
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1612131836050.3415@nanos
Signed-off-by: Thomas Gleixner

cpumask: fix code comment

2016-08-02T23:35:24+00:00

Fix code comment for cpumask_parse().

Link: http://lkml.kernel.org/r/71aae2c60ae5dae0cf554199ce6aea8f88c69347.1465380581.git.geliangtang@gmail.com
Signed-off-by: Geliang Tang 
Acked-by: Rusty Russell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched: Allow per-cpu kernel threads to run on online && !active

2016-05-06T12:58:22+00:00

In order to enable symmetric hotplug, we must mirror the online &&
!active state of cpu-down on the cpu-up side.

However, to retain sanity, limit this state to per-cpu kthreads.

Aside from the change to set_cpus_allowed_ptr(), which allow moving
the per-cpu kthreads on, the other critical piece is the cpu selection
for pinned tasks in select_task_rq(). This avoids dropping into
select_fallback_rq().

select_fallback_rq() cannot be allowed to select !active cpus because
its used to migrate user tasks away. And we do not want to move user
tasks onto cpus that are in transition.

Requested-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Thomas Gleixner 
Cc: Lai Jiangshan 
Cc: Jan H. Schönherr 
Cc: Oleg Nesterov 
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160301152303.GV6356@twins.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner

cpumask: remove incorrect information from comment

2016-03-22T22:36:02+00:00

Since commit cdfdef75e795 ("cpumask: only allocate nr_cpumask_bits."),
this comment above cpumask_size() is no longer relevant.

Signed-off-by: Eric Biggers 
Cc: Rusty Russell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/cpu.c: make set_cpu_* static inlines

2016-01-21T01:09:18+00:00

Almost all callers of the set_cpu_* functions pass an explicit true or
false.  Making them static inline thus replaces the function calls with a
simple set_bit/clear_bit, saving some .text.

Signed-off-by: Rasmus Villemoes 
Acked-by: Rusty Russell 
Cc: Greg Kroah-Hartman 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/cpu.c: eliminate cpu_*_mask

2016-01-21T01:09:18+00:00

Replace the variables cpu_possible_mask, cpu_online_mask, cpu_present_mask
and cpu_active_mask with macros expanding to expressions of the same type
and value, eliminating some indirection.

Signed-off-by: Rasmus Villemoes 
Acked-by: Rusty Russell 
Cc: Greg Kroah-Hartman 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/cpu.c: export __cpu_*_mask

2016-01-21T01:09:18+00:00

Exporting the cpumasks __cpu_possible_mask and friends will allow us to
remove the extra indirection through the cpu_*_mask variables.  It will
also allow the set_cpu_* functions to become static inlines, which will
give a .text reduction.

Signed-off-by: Rasmus Villemoes 
Acked-by: Rusty Russell 
Cc: Greg Kroah-Hartman 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds