sched/docbook: Fix 'make htmldocs' warnings caused by missing description

When 'flags' argument to sched_{set,get}attr() syscalls were
added in:

  6d35ab48090b ("sched: Add 'flags' argument to sched_{set,get}attr() syscalls")

no description for 'flags' was added. It causes the following warnings on "make htmldocs":

  Warning(/kernel/sched/core.c:3645): No description found for parameter 'flags'
  Warning(/kernel/sched/core.c:3789): No description found for parameter 'flags'

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1397753955-2914-1-git-send-email-standby24x7@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf: Fix race in removing an event

When removing a (sibling) event we do:

	raw_spin_lock_irq(&ctx->lock);
	perf_group_detach(event);
	raw_spin_unlock_irq(&ctx->lock);

	<hole>

	perf_remove_from_context(event);
		raw_spin_lock_irq(&ctx->lock);
		...
		raw_spin_unlock_irq(&ctx->lock);

Now, assuming the event is a sibling, it will be 'unreachable' for
things like ctx_sched_out() because that iterates the
groups->siblings, and we just unhooked the sibling.

So, if during <hole> we get ctx_sched_out(), it will miss the event
and not call event_sched_out() on it, leaving it programmed on the
PMU.

The subsequent perf_remove_from_context() call will find the ctx is
inactive and only call list_del_event() to remove the event from all
other lists.

Hereafter we can proceed to free the event; while still programmed!

Close this hole by moving perf_group_detach() inside the same
ctx->lock region(s) perf_remove_from_context() has.

The condition on inherited events only in __perf_event_exit_task() is
likely complete crap because non-inherited events are part of groups
too and we're tearing down just the same. But leave that for another
patch.

Most-likely-Fixes: e03a9a55b4e ("perf: Change close() semantics for group events")
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Much-staring-at-traces-by: Vince Weaver <vincent.weaver@maine.edu>
Much-staring-at-traces-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140505093124.GN17778@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf: Fix perf_event_init_context()

perf_pin_task_context() can return NULL but perf_event_init_context()
assumes it will not, correct this.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: http://lkml.kernel.org/r/20140505171428.GU26782@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf/x86/intel: Fix Silvermont's event constraints

Event 0x013c is not the same as fixed counter2, remove it from
Silvermont's event constraints.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1398755081-12471-1-git-send-email-zheng.z.yan@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: Sanitize irq accounting madness

Russell reported, that irqtime_account_idle_ticks() takes ages due to:

       for (i = 0; i < ticks; i++)
               irqtime_account_process_tick(current, 0, rq);

It's sad, that this code was written way _AFTER_ the NOHZ idle
functionality was available. I charge myself guitly for not paying
attention when that crap got merged with commit abb74cefa ("sched:
Export ns irqtimes through /proc/stat")

So instead of looping nr_ticks times just apply the whole thing at
once.

As a side note: The whole cputime_t vs. u64 business in that context
wants to be cleaned up as well. There is no point in having all these
back and forth conversions. Lets standardise on u64 nsec for all
kernel internal accounting and be done with it. Everything else does
not make sense at all for fine grained accounting. Frederic, can you
please take care of that?

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Shaun Ruffell <sruffell@digium.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1405022307000.6261@ionos.tec.linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched/deadline: Fix sched_yield() behavior

yield_task_dl() is broken:

 o it forces current to be throttled setting its runtime to zero;
 o it sets current's dl_se->dl_new to one, expecting that dl_task_timer()
   will queue it back with proper parameters at replenish time.

Unfortunately, dl_task_timer() has this check at the very beginning:

	if (!dl_task(p) || dl_se->dl_new)
		goto unlock;

So, it just bails out and the task is never replenished. It actually
yielded forever.

To fix this, introduce a new flag indicating that the task properly yielded
the CPU before its current runtime expired. While this is a little overdoing
at the moment, the flag would be useful in the future to discriminate between
"good" jobs (of which remaining runtime could be reclaimed, i.e. recycled)
and "bad" jobs (for which dl_throttled task has been set) that needed to be
stopped.

Reported-by: yjay.kim <yjay.kim@lge.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140429103953.e68eba1b2ac3309214e3dc5a@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched/deadline: Fix memory leak

Free cpudl->free_cpus allocated in cpudl_init().

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # 3.14+
Link: http://lkml.kernel.org/r/534F36CE.2000409@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: Use CPUPRI_NR_PRIORITIES instead of MAX_RT_PRIO in cpupri check

The check at the beginning of cpupri_find() makes sure that the task_pri
variable does not exceed the cp->pri_to_cpu array length. But that length
is CPUPRI_NR_PRIORITIES not MAX_RT_PRIO, where it will miss the last two
priorities in that array.

As task_pri is computed from convert_prio() which should never be bigger
than CPUPRI_NR_PRIORITIES, if the check should cause a panic if it is
hit.

Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1397015410.5212.13.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: Skip double execution of pick_next_task_fair()

Tim wrote:

 "The current code will call pick_next_task_fair a second time in the
  slow path if we did not pull any task in our first try.  This is
  really unnecessary as we already know no task can be pulled and it
  doubles the delay for the cpu to enter idle.

  We instrumented some network workloads and that saw that
  pick_next_task_fair is frequently called twice before a cpu enters
  idle.  The call to pick_next_task_fair can add non trivial latency as
  it calls load_balance which runs find_busiest_group on an hierarchy of
  sched domains spanning the cpus for a large system.  For some 4 socket
  systems, we saw almost 0.25 msec spent per call of pick_next_task_fair
  before a cpu can be idled."

Optimize the second call away for the common case and document the
dependency.

Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Len Brown <len.brown@intel.com>
Link: http://lkml.kernel.org/r/20140424100047.GP11096@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: Fix updating rq->max_idle_balance_cost and rq->next_balance in idle_balance()

The following commit:

  e5fc66119ec9 ("sched: Fix race in idle_balance()")

can potentially cause rq->max_idle_balance_cost to not be updated,
even when load_balance(NEWLY_IDLE) is attempted and the per-sd
max cost value is updated.

Preeti noticed a similar issue with updating rq->next_balance.

In this patch, we fix this by making sure we still check/update those values
even if a task gets enqueued while browsing the domains.

Signed-off-by: Jason Low <jason.low2@hp.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: morten.rasmussen@arm.com
Cc: aswin@hp.com
Cc: daniel.lezcano@linaro.org
Cc: alex.shi@linaro.org
Cc: efault@gmx.de
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1398725155-7591-2-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched/numa: Initialize newidle balance stats in sd_numa_init()

Also initialize the per-sd variables for newidle load balancing
in sd_numa_init().

Signed-off-by: Jason Low <jason.low2@hp.com>
Acked-by: morten.rasmussen@arm.com
Cc: daniel.lezcano@linaro.org
Cc: alex.shi@linaro.org
Cc: preeti@linux.vnet.ibm.com
Cc: efault@gmx.de
Cc: vincent.guittot@linaro.org
Cc: aswin@hp.com
Cc: chegu_vinod@hp.com
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1398303035-18255-3-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
tools/liblockdep: Build liblockdep from tools/Makefile

add targets to build liblockdep with
  make -C tools liblockdep
like the way other stuff under tools/ can be built

Signed-off-by: S. Lockwood-Childs <sjl@vctlabs.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
tools/liblockdep: Remove all build files when doing make clean

We forgot to remove the shared library with the version number when
'make clean' ran, fix the clean pattern.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Merge branch 'liblockdep-fixes-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/sashal/linux into perf/urgent

Pull liblockdep fixes from Sasha Levin, to fix two build related bugs.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf: Limit perf_event_attr::sample_period to 63 bits

Vince reported that using a large sample_period (one with bit 63 set)
results in wreckage since while the sample_period is fundamentally
unsigned (negative periods don't make sense) the way we implement
things very much rely on signed logic.

So limit sample_period to 63 bits to avoid tripping over this.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
perf: Prevent false warning in perf_swevent_add

The perf cpu offline callback takes down all cpu context
events and releases swhash->swevent_hlist.

This could race with task context software event being just
scheduled on this cpu via perf_swevent_add while cpu hotplug
code already cleaned up event's data.

The race happens in the gap between the cpu notifier code
and the cpu being actually taken down. Note that only cpu
ctx events are terminated in the perf cpu hotplug code.

It's easily reproduced with:
  $ perf record -e faults perf bench sched pipe

while putting one of the cpus offline:
  # echo 0 > /sys/devices/system/cpu/cpu1/online

Console emits following warning:
  WARNING: CPU: 1 PID: 2845 at kernel/events/core.c:5672 perf_swevent_add+0x18d/0x1a0()
  Modules linked in:
  CPU: 1 PID: 2845 Comm: sched-pipe Tainted: G        W    3.14.0+ #256
  Hardware name: Intel Corporation Montevina platform/To be filled by O.E.M., BIOS AMVACRB1.86C.0066.B00.0805070703 05/07/2008
   0000000000000009 ffff880077233ab8 ffffffff81665a23 0000000000200005
   0000000000000000 ffff880077233af8 ffffffff8104732c 0000000000000046
   ffff88007467c800 0000000000000002 ffff88007a9cf2a0 0000000000000001
  Call Trace:
   [<ffffffff81665a23>] dump_stack+0x4f/0x7c
   [<ffffffff8104732c>] warn_slowpath_common+0x8c/0xc0
   [<ffffffff8104737a>] warn_slowpath_null+0x1a/0x20
   [<ffffffff8110fb3d>] perf_swevent_add+0x18d/0x1a0
   [<ffffffff811162ae>] event_sched_in.isra.75+0x9e/0x1f0
   [<ffffffff8111646a>] group_sched_in+0x6a/0x1f0
   [<ffffffff81083dd5>] ? sched_clock_local+0x25/0xa0
   [<ffffffff811167e6>] ctx_sched_in+0x1f6/0x450
   [<ffffffff8111757b>] perf_event_sched_in+0x6b/0xa0
   [<ffffffff81117a4b>] perf_event_context_sched_in+0x7b/0xc0
   [<ffffffff81117ece>] __perf_event_task_sched_in+0x43e/0x460
   [<ffffffff81096f1e>] ? put_lock_stats.isra.18+0xe/0x30
   [<ffffffff8107b3c8>] finish_task_switch+0xb8/0x100
   [<ffffffff8166a7de>] __schedule+0x30e/0xad0
   [<ffffffff81172dd2>] ? pipe_read+0x3e2/0x560
   [<ffffffff8166b45e>] ? preempt_schedule_irq+0x3e/0x70
   [<ffffffff8166b45e>] ? preempt_schedule_irq+0x3e/0x70
   [<ffffffff8166b464>] preempt_schedule_irq+0x44/0x70
   [<ffffffff816707f0>] retint_kernel+0x20/0x30
   [<ffffffff8109e60a>] ? lockdep_sys_exit+0x1a/0x90
   [<ffffffff812a4234>] lockdep_sys_exit_thunk+0x35/0x67
   [<ffffffff81679321>] ? sysret_check+0x5/0x56

Fixing this by tracking the cpu hotplug state and displaying
the WARN only if current cpu is initialized properly.

Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: stable@vger.kernel.org
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1396861448-10097-1-git-send-email-jolsa@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
perf: Fix a race between ring_buffer_detach() and ring_buffer_attach()

Alexander noticed that we use RCU iteration on rb->event_list but do
not use list_{add,del}_rcu() to add,remove entries to that list, nor
do we observe proper grace periods when re-using the entries.

Merge ring_buffer_detach() into ring_buffer_attach() such that
attaching to the NULL buffer is detaching.

Furthermore, ensure that between any 'detach' and 'attach' of the same
event we observe the required grace period, but only when strictly
required. In effect this means that only ioctl(.request =
PERF_EVENT_IOC_SET_OUTPUT) will wait for a grace period, while the
normal initial attach and final detach will not be delayed.

This patch should, I think, do the right thing under all
circumstances, the 'normal' cases all should never see the extra grace
period, but the two cases:

 1) PERF_EVENT_IOC_SET_OUTPUT on an event which already has a
    ring_buffer set, will now observe the required grace period between
    removing itself from the old and attaching itself to the new buffer.

    This case is 'simple' in that both buffers are present in
    perf_event_set_output() one could think an unconditional
    synchronize_rcu() would be sufficient; however...

 2) an event that has a buffer attached, the buffer is destroyed
    (munmap) and then the event is attached to a new/different buffer
    using PERF_EVENT_IOC_SET_OUTPUT.

    This case is more complex because the buffer destruction does:
      ring_buffer_attach(.rb = NULL)
    followed by the ioctl() doing:
      ring_buffer_attach(.rb = foo);

    and we still need to observe the grace period between these two
    calls due to us reusing the event->rb_entry list_head.

In order to make 2 happen we use Paul's latest cond_synchronize_rcu()
call.

Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Reported-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140507123526.GD13658@twins.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Ingo Molnar:
 "The biggest changes are fixes for races that kept triggering Trinity
  crashes, plus liblockdep build fixes and smaller misc fixes.

  The liblockdep bits in perf/urgent are a pull mistake - they should
  have been in locking/urgent - but by the time I noticed other commits
  were added and testing was done :-/ Sorry about that"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix a race between ring_buffer_detach() and ring_buffer_attach()
  perf: Prevent false warning in perf_swevent_add
  perf: Limit perf_event_attr::sample_period to 63 bits
  tools/liblockdep: Remove all build files when doing make clean
  tools/liblockdep: Build liblockdep from tools/Makefile
  perf/x86/intel: Fix Silvermont's event constraints
  perf: Fix perf_event_init_context()
  perf: Fix race in removing an event
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:
 "The biggest commit is an irqtime accounting loop latency fix, the rest
  are misc fixes all over the place: deadline scheduling, docs, numa,
  balancer and a bad to-idle latency fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/numa: Initialize newidle balance stats in sd_numa_init()
  sched: Fix updating rq->max_idle_balance_cost and rq->next_balance in idle_balance()
  sched: Skip double execution of pick_next_task_fair()
  sched: Use CPUPRI_NR_PRIORITIES instead of MAX_RT_PRIO in cpupri check
  sched/deadline: Fix memory leak
  sched/deadline: Fix sched_yield() behavior
  sched: Sanitize irq accounting madness
  sched/docbook: Fix 'make htmldocs' warnings caused by missing description