The NUMA balancing code implements delays in scanning by
advancing curr->node_stamp beyond curr->se.sum_exec_runtime.

With unsigned math, that creates an underflow, which results
in task_numa_work being queued all the time, even when we
don't want to.

Avoiding the math underflow makes it possible to reduce CPU
overhead in the NUMA balancing code.
Reported-and-tested-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mgorman@suse.de
Link: http://lkml.kernel.org/r/1446756983-28173-2-git-send-email-riel@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

Pull x86 platform changes from Ingo Molnar:
 "Misc updates to the Intel MID and SGI UV platforms"

* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/intel-mid: Make intel_mid_ops static
  arch/x86/intel-mid: Use kmemdup rather than duplicating its implementation
  x86/platform/uv: Implement simple dump failover if kdump fails
  x86/platform/uv: Insert per_cpu accessor function on uv_hub_nmi

Pull x86 mm changes from Ingo Molnar:
 "The main changes are: continued PAT work by Toshi Kani, plus a new
  boot time warning about insecure RWX kernel mappings, by Stephen
  Smalley.

  The new CONFIG_DEBUG_WX=y warning is marked default-y if
  CONFIG_DEBUG_RODATA=y is already eanbled, as a special exception, as
  these bugs are hard to notice and this check already found several
  live bugs"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Warn on W^X mappings
  x86/mm: Fix no-change case in try_preserve_large_page()
  x86/mm: Fix __split_large_page() to handle large PAT bit
  x86/mm: Fix try_preserve_large_page() to handle large PAT bit
  x86/mm: Fix gup_huge_p?d() to handle large PAT bit
  x86/mm: Fix slow_virt_to_phys() to handle large PAT bit
  x86/mm: Fix page table dump to show PAT bit
  x86/asm: Add pud_pgprot() and pmd_pgprot()
  x86/asm: Fix pud/pmd interfaces to handle large PAT bit
  x86/asm: Add pud/pmd mask interfaces to handle large PAT bit
  x86/asm: Move PUD_PAGE macros to page_types.h
  x86/vdso32: Define PGTABLE_LEVELS to 32bit VDSO

Pull x86 sigcontext header cleanups from Ingo Molnar:
 "This series reorganizes and cleans up various aspects of the main
  sigcontext UAPI headers, such as unifying the data structures and
  updating/adding lots of comments to explain all the ABI details and
  quirks.  The headers can now also be built in user-space standalone"

* 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/headers: Clean up too long lines
  x86/headers: Remove <asm/sigcontext.h> references on the kernel side
  x86/headers: Remove direct sigcontext32.h uses
  x86/headers: Convert sigcontext_ia32 uses to sigcontext_32
  x86/headers: Unify 'struct sigcontext_ia32' and 'struct sigcontext_32'
  x86/headers: Make sigcontext pointers bit independent
  x86/headers: Move the 'struct sigcontext' definitions into the UAPI header
  x86/headers: Clean up the kernel's struct sigcontext types to be ABI-clean
  x86/headers: Convert uses of _fpstate_ia32 to _fpstate_32
  x86/headers: Unify 'struct _fpstate_ia32' and i386 struct _fpstate
  x86/headers: Unify register type definitions between 32-bit compat and i386
  x86/headers: Use ABI types consistently in sigcontext*.h
  x86/headers: Separate out legacy user-space structure definitions
  x86/headers: Clean up and better document uapi/asm/sigcontext.h
  x86/headers: Clean up uapi/asm/sigcontext32.h
  x86/headers: Fix (old) header file dependency bug in uapi/asm/sigcontext32.h

Pull x86 fpu changes from Ingo Molnar:
 "There are two main areas of changes:

   - Rework of the extended FPU state code to robustify the kernel's
     usage of cpuid provided xstate sizes - and related changes (Dave
     Hansen)"

   - math emulation enhancements: new modern FPU instructions support,
     with testcases, plus cleanups (Denys Vlasnko)"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86/fpu: Fixup uninitialized feature_name warning
  x86/fpu/math-emu: Add support for FISTTP instructions
  x86/fpu/math-emu, selftests: Add test for FISTTP instructions
  x86/fpu/math-emu: Add support for FCMOVcc insns
  x86/fpu/math-emu: Add support for F[U]COMI[P] insns
  x86/fpu/math-emu: Remove define layer for undocumented opcodes
  x86/fpu/math-emu, selftests: Add tests for FCMOV and FCOMI insns
  x86/fpu/math-emu: Remove !NO_UNDOC_CODE
  x86/fpu: Check CPU-provided sizes against struct declarations
  x86/fpu: Check to ensure increasing-offset xstate offsets
  x86/fpu: Correct and check XSAVE xstate size calculations
  x86/fpu: Add C structures for AVX-512 state components
  x86/fpu: Rework YMM definition
  x86/fpu/mpx: Rework MPX 'xstate' types
  x86/fpu: Add xfeature_enabled() helper instead of test_bit()
  x86/fpu: Remove 'xfeature_nr'
  x86/fpu: Rework XSTATE_* macros to remove magic '2'
  x86/fpu: Rename XFEATURES_NR_MAX
  x86/fpu: Rename XSAVE macros
  x86/fpu: Remove partial LWP support definitions
  ...

Pull x86 kgdb fixlet from Ingo Molnar:
 "A single debugging related commit: compress the memory usage of a kgdb
  data structure"

* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kgdb: Replace bool_int_array[NR_CPUS] with bitmap

Pull x86 cpu changes from Ingo Molnar:
 "Two changes in this cycle: a Kconfig help text enhancement, and an AMD
  CLZERO instruction capability detection and enumeration"

* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu: Add CLZERO detection
  x86/Kconfig/cpus: Fix/complete CPU type help texts

Pull x86 cleanups from Ingo Molnar:
 "An early_printk cleanup plus deinlining enhancements"

* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/early_printk: Set __iomem address space for IO
  x86/signal: Deinline get_sigframe, save 240 bytes
  x86: Deinline early_console_register, save 403 bytes
  x86/e820: Deinline e820_type_to_string, save 126 bytes

Pull x86 boot cleanup from Ingo Molnar:
 "A single commit: remove an obsolete kcrash boot flag"

* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kexec: Remove obsolete 'in_crash_kexec' flag

Pull x86 asm changes from Ingo Molnar:
 "The main change in this cycle is another step in the big x86 system
  call interface rework by Andy Lutomirski, which moves most of the low
  level x86 entry code from assembly to C, for all syscall entries
  except native 64-bit system calls:

    arch/x86/entry/entry_32.S        | 182 ++++------
    arch/x86/entry/entry_64_compat.S | 547 ++++++++-----------------------
    194 insertions(+), 535 deletions(-)

  ... our hope is that the final remaining step (converting native
  64-bit system calls) will be less painful as all the previous steps,
  given that most of the legacies and quirks are concentrated around
  native 32-bit and compat environments"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
  x86/entry/32: Fix FS and GS restore in opportunistic SYSEXIT
  x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on
  um/x86: Fix build after x86 syscall changes
  x86/asm: Remove the xyz_cfi macros from dwarf2.h
  selftests/x86: Style fixes for the 'unwind_vdso' test
  x86/entry/64/compat: Document sysenter_fix_flags's reason for existence
  x86/entry: Split and inline syscall_return_slowpath()
  x86/entry: Split and inline prepare_exit_to_usermode()
  x86/entry: Use pt_regs_to_thread_info() in syscall entry tracing
  x86/entry: Hide two syscall entry assertions behind CONFIG_DEBUG_ENTRY
  x86/entry: Micro-optimize compat fast syscall arg fetch
  x86/entry: Force inlining of 32-bit syscall code
  x86/entry: Make irqs_disabled checks in exit code depend on lockdep
  x86/entry: Remove unnecessary IRQ twiddling in fast 32-bit syscalls
  x86/asm: Remove thread_info.sysenter_return
  x86/entry/32: Re-implement SYSENTER using the new C path
  x86/entry/32: Switch INT80 to the new C syscall path
  x86/entry/32: Open-code return tracking from fork and kthreads
  x86/entry/compat: Implement opportunistic SYSRETL for compat syscalls
  x86/vdso/compat: Wire up SYSENTER and SYSCSALL for compat userspace
  ...

Pull x86 apic changes from Ingo Molnar:
 "The main changes in this cycle were:

   - Numachip updates: new hardware support, fixes and cleanups.
     (Daniel J Blueman)

   - misc smaller cleanups and fixlets"

* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/io_apic: Make eoi_ioapic_pin() static
  x86/irq: Drop unlikely before IS_ERR_OR_NULL
  x86/x2apic: Make stub functions available even if !CONFIG_X86_LOCAL_APIC
  x86/apic: Deinline various functions
  x86/numachip: Fix timer build conflict
  x86/numachip: Introduce Numachip2 timer mechanisms
  x86/numachip: Add Numachip IPI optimisations
  x86/numachip: Add Numachip2 APIC support
  x86/numachip: Cleanup Numachip support

Pull scheduler changes from Ingo Molnar:
 "The main changes in this cycle were:

   - sched/fair load tracking fixes and cleanups (Byungchul Park)

   - Make load tracking frequency scale invariant (Dietmar Eggemann)

   - sched/deadline updates (Juri Lelli)

   - stop machine fixes, cleanups and enhancements for bugs triggered by
     CPU hotplug stress testing (Oleg Nesterov)

   - scheduler preemption code rework: remove PREEMPT_ACTIVE and related
     cleanups (Peter Zijlstra)

   - Rework the sched_info::run_delay code to fix races (Peter Zijlstra)

   - Optimize per entity utilization tracking (Peter Zijlstra)

   - ... misc other fixes, cleanups and smaller updates"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
  sched: Don't scan all-offline ->cpus_allowed twice if !CONFIG_CPUSETS
  sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop()
  sched: Start stopper early
  stop_machine: Kill cpu_stop_threads->setup() and cpu_stop_unpark()
  stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
  stop_machine: Change cpu_stop_queue_two_works() to rely on stopper->enabled
  stop_machine: Introduce __cpu_stop_queue_work() and cpu_stop_queue_two_works()
  stop_machine: Ensure that a queued callback will be called before cpu_stop_park()
  sched/x86: Fix typo in __switch_to() comments
  sched/core: Remove a parameter in the migrate_task_rq() function
  sched/core: Drop unlikely behind BUG_ON()
  sched/core: Fix task and run queue sched_info::run_delay inconsistencies
  sched/numa: Fix task_tick_fair() from disabling numa_balancing
  sched/core: Add preempt_count invariant check
  sched/core: More notrace annotations
  sched/core: Kill PREEMPT_ACTIVE
  sched/core, sched/x86: Kill thread_info::saved_preempt_count
  sched/core: Simplify preempt_count tests
  sched/core: Robustify preemption leak checks
  sched/core: Stop setting PREEMPT_ACTIVE
  ...

Pull RAS changes from Ingo Molnar:
 "The main system reliability related changes were from x86, but also
  some generic RAS changes:

   - AMD MCE error injection subsystem enhancements.  (Aravind
     Gopalakrishnan)

   - Fix MCE and CPU hotplug interaction bug.  (Ashok Raj)

   - kcrash bootup robustness fix.  (Baoquan He)

   - kcrash cleanups.  (Borislav Petkov)

   - x86 microcode driver rework: simplify it by unmodularizing it and
     other cleanups.  (Borislav Petkov)"

* 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86/mce: Add a default case to the switch in __mcheck_cpu_ancient_init()
  x86/mce: Add a Scalable MCA vendor flags bit
  MAINTAINERS: Unify the microcode driver section
  x86/microcode/intel: Move #ifdef DEBUG inside the function
  x86/microcode/amd: Remove maintainers from comments
  x86/microcode: Remove modularization leftovers
  x86/microcode: Merge the early microcode loader
  x86/microcode: Unmodularize the microcode driver
  x86/mce: Fix thermal throttling reporting after kexec
  kexec/crash: Say which char is the unrecognized
  x86/setup/crash: Check memblock_reserve() retval
  x86/setup/crash: Cleanup some more
  x86/setup/crash: Remove alignment variable
  x86/setup: Cleanup crashkernel reservation functions
  x86/amd_nb, EDAC: Rename amd_get_node_id()
  x86/setup: Do not reserve crashkernel high memory if low reservation failed
  x86/microcode/amd: Do not overwrite final patch levels
  x86/microcode/amd: Extract current patch level read to a function
  x86/ras/mce_amd_inj: Inject bank 4 errors on the NBC
  x86/ras/mce_amd_inj: Trigger deferred and thresholding errors interrupts
  ...

Pull perf updates from Ingo Molnar:
 "Kernel side changes:

   - Improve accuracy of perf/sched clock on x86.  (Adrian Hunter)

   - Intel DS and BTS updates.  (Alexander Shishkin)

   - Intel cstate PMU support.  (Kan Liang)

   - Add group read support to perf_event_read().  (Peter Zijlstra)

   - Branch call hardware sampling support, implemented on x86 and
     PowerPC.  (Stephane Eranian)

   - Event groups transactional interface enhancements.  (Sukadev
     Bhattiprolu)

   - Enable proper x86/intel/uncore PMU support on multi-segment PCI
     systems.  (Taku Izumi)

   - ... misc fixes and cleanups.

  The perf tooling team was very busy again with 200+ commits, the full
  diff doesn't fit into lkml size limits.  Here's an (incomplete) list
  of the tooling highlights:

  New features:

   - Change the default event used in all tools (record/top): use the
     most precise "cycles" hw counter available, i.e. when the user
     doesn't specify any event, it will try using cycles:ppp, cycles:pp,
     etc and fall back transparently until it finds a working counter.
     (Arnaldo Carvalho de Melo)

   - Integration of perf with eBPF that, given an eBPF .c source file
     (or .o file built for the 'bpf' target with clang), will get it
     automatically built, validated and loaded into the kernel via the
     sys_bpf syscall, which can then be used and seen using 'perf trace'
     and other tools.

     (Wang Nan)

  Various user interface improvements:

   - Automatic pager invocation on long help output.  (Namhyung Kim)

   - Search for more options when passing args to -h, e.g.: (Arnaldo
     Carvalho de Melo)

        $ perf report -h interface

        Usage: perf report [<options>]

         --gtk    Use the GTK2 interface
         --stdio  Use the stdio interface
         --tui    Use the TUI interface

   - Show ordered command line options when -h is used or when an
     unknown option is specified.  (Arnaldo Carvalho de Melo)

   - If options are passed after -h, show just its descriptions, not all
     options.  (Arnaldo Carvalho de Melo)

   - Implement column based horizontal scrolling in the hists browser
     (top, report), making it possible to use the TUI for things like
     'perf mem report' where there are many more columns than can fit in
     a terminal.  (Arnaldo Carvalho de Melo)

   - Enhance the error reporting of tracepoint event parsing, e.g.:

       $ oldperf record -e sched:sched_switc usleep 1
       event syntax error: 'sched:sched_switc'
                            \___ unknown tracepoint
       Run 'perf list' for a list of valid events

     Now we get the much nicer:

       $ perf record -e sched:sched_switc ls
       event syntax error: 'sched:sched_switc'
                            \___ can't access trace events

       Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_switc
       Hint:  Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'

     And after we have those mount point permissions fixed:

       $ perf record -e sched:sched_switc ls
       event syntax error: 'sched:sched_switc'
                            \___ unknown tracepoint

       Error: File /sys/kernel/debug/tracing/events/sched/sched_switc not found.
       Hint:  Perhaps this kernel misses some CONFIG_ setting to enable this feature?.

     I.e.  basically now the event parsing routing uses the strerror_open()
     routines introduced by and used in 'perf trace' work.  (Jiri Olsa)

   - Fail properly when pattern matching fails to find a tracepoint,
     i.e. '-e non:existent' was being correctly handled, with a proper
     error message about that not being a valid event, but '-e
     non:existent*' wasn't, fix it.  (Jiri Olsa)

   - Do event name substring search as last resort in 'perf list'.
     (Arnaldo Carvalho de Melo)

     E.g.:

       # perf list clock

       List of pre-defined events (to be used in -e):

        cpu-clock                                          [Software event]
        task-clock                                         [Software event]

        uncore_cbox_0/clockticks/                          [Kernel PMU event]
        uncore_cbox_1/clockticks/                          [Kernel PMU event]

        kvm:kvm_pvclock_update                             [Tracepoint event]
        kvm:kvm_update_master_clock                        [Tracepoint event]
        power:clock_disable                                [Tracepoint event]
        power:clock_enable                                 [Tracepoint event]
        power:clock_set_rate                               [Tracepoint event]
        syscalls:sys_enter_clock_adjtime                   [Tracepoint event]
        syscalls:sys_enter_clock_getres                    [Tracepoint event]
        syscalls:sys_enter_clock_gettime                   [Tracepoint event]
        syscalls:sys_enter_clock_nanosleep                 [Tracepoint event]
        syscalls:sys_enter_clock_settime                   [Tracepoint event]
        syscalls:sys_exit_clock_adjtime                    [Tracepoint event]
        syscalls:sys_exit_clock_getres                     [Tracepoint event]
        syscalls:sys_exit_clock_gettime                    [Tracepoint event]
        syscalls:sys_exit_clock_nanosleep                  [Tracepoint event]
        syscalls:sys_exit_clock_settime                    [Tracepoint event]

  Intel PT hardware tracing enhancements:

   - Accept a zero --itrace period, meaning "as often as possible".  In
     the case of Intel PT that is the same as a period of 1 and a unit
     of 'instructions' (i.e.  --itrace=i1i).  (Adrian Hunter)

   - Harmonize itrace's synthesized callchains with the existing
     --max-stack tool option.  (Adrian Hunter)

   - Allow time to be displayed in nanoseconds in 'perf script'.
     (Adrian Hunter)

   - Fix potential infinite loop when handling Intel PT timestamps.
     (Adrian Hunter)

   - Slighly improve Intel PT debug logging.  (Adrian Hunter)

   - Warn when AUX data has been lost, just like when processing
     PERF_RECORD_LOST.  (Adrian Hunter)

   - Further document export-to-postgresql.py script.  (Adrian Hunter)

   - Add option to synthesize branch stack from auxtrace data.  (Adrian
     Hunter)

  Misc notable changes:

   - Switch the default callchain output mode to 'graph,0.5,caller', to
     make it look like the default for other tools, reducing the
     learning curve for people used to 'caller' based viewing.  (Arnaldo
     Carvalho de Melo)

   - various call chain usability enhancements.  (Namhyung Kim)

   - Introduce the 'P' event modifier, meaning 'max precision level,
     please', i.e.:

        $ perf record -e cycles:P usleep 1

     Is now similar to:

        $ perf record usleep 1

     Useful, for instance, when specifying multiple events.  (Jiri Olsa)

   - Add 'socket' sort entry, to sort by the processor socket in 'perf
     top' and 'perf report'.  (Kan Liang)

   - Introduce --socket-filter to 'perf report', for filtering by
     processor socket.  (Kan Liang)

   - Add new "Zoom into Processor Socket" operation in the perf hists
     browser, used in 'perf top' and 'perf report'.  (Kan Liang)

   - Allow probing on kmodules without DWARF.  (Masami Hiramatsu)

   - Fix 'perf probe -l' for probes added to kernel module functions.
     (Masami Hiramatsu)

   - Preparatory work for the 'perf stat record' feature that will allow
     generating perf.data files with counting data in addition to the
     sampling mode we have now (Jiri Olsa)

   - Update libtraceevent KVM plugin.  (Paolo Bonzini)

   - ... plus lots of other enhancements that I failed to list properly,
     by: Adrian Hunter, Alexander Shishkin, Andi Kleen, Andrzej Hajda,
     Arnaldo Carvalho de Melo, Dima Kogan, Don Zickus, Geliang Tang, He
     Kuang, Huaitong Han, Ingo Molnar, Jan Stancek, Jiri Olsa, Kan
     Liang, Kirill Tkhai, Masami Hiramatsu, Matt Fleming, Namhyung Kim,
     Paolo Bonzini, Peter Zijlstra, Rabin Vincent, Scott Wood, Stephane
     Eranian, Sukadev Bhattiprolu, Taku Izumi, Vaishali Thakkar, Wang
     Nan, Yang Shi and Yunlong Song"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (260 commits)
  perf unwind: Pass symbol source to libunwind
  tools build: Fix libiberty feature detection
  perf tools: Compile scriptlets to BPF objects when passing '.c' to --event
  perf record: Add clang options for compiling BPF scripts
  perf bpf: Attach eBPF filter to perf event
  perf tools: Make sure fixdep is built before libbpf
  perf script: Enable printing of branch stack
  perf trace: Add cmd string table to decode sys_bpf first arg
  perf bpf: Collect perf_evsel in BPF object files
  perf tools: Load eBPF object into kernel
  perf tools: Create probe points for BPF programs
  perf tools: Enable passing bpf object file to --event
  perf ebpf: Add the libbpf glue
  perf tools: Make perf depend on libbpf
  perf symbols: Fix endless loop in dso__split_kallsyms_for_kcore
  perf tools: Enable pre-event inherit setting by config terms
  perf symbols: we can now read separate debug-info files based on a build ID
  perf symbols: Fix type error when reading a build-id
  perf tools: Search for more options when passing args to -h
  perf stat: Cache aggregated map entries in extra cpumap
  ...

This seems to be a mis-reading of how alpha memory ordering works, and
is not backed up by the alpha architecture manual.  The helper functions
don't do anything special on any other architectures, and the arguments
that support them being safe on other architectures also argue that they
are safe on alpha.

Basically, the "control dependency" is between a previous read and a
subsequent write that is dependent on the value read.  Even if the
subsequent write is actually done speculatively, there is no way that
such a speculative write could be made visible to other cpu's until it
has been committed, which requires validating the speculation.

Note that most weakely ordered architectures (very much including alpha)
do not guarantee any ordering relationship between two loads that depend
on each other on a control dependency:

    read A
    if (val == 1)
        read B

because the conditional may be predicted, and the "read B" may be
speculatively moved up to before reading the value A.  So we require the
user to insert a smp_rmb() between the two accesses to be correct:

    read A;
    if (A == 1)
        smp_rmb()
        read B

Alpha is further special in that it can break that ordering even if the
*address* of B depends on the read of A, because the cacheline that is
read later may be stale unless you have a memory barrier in between the
pointer read and the read of the value behind a pointer:

    read ptr
    read offset(ptr)

whereas all other weakly ordered architectures guarantee that the data
dependency (as opposed to just a control dependency) will order the two
accesses.  As a result, alpha needs a "smp_read_barrier_depends()" in
between those two reads for them to be ordered.

The coontrol dependency that "READ_ONCE_CTRL()" and "atomic_read_ctrl()"
had was a control dependency to a subsequent *write*, however, and
nobody can finalize such a subsequent write without having actually done
the read.  And were you to write such a value to a "stale" cacheline
(the way the unordered reads came to be), that would seem to lose the
write entirely.

So the things that make alpha able to re-order reads even more
aggressively than other weak architectures do not seem to be relevant
for a subsequent write.  Alpha memory ordering may be strange, but
there's no real indication that it is *that* strange.

Also, the alpha architecture reference manual very explicitly talks
about the definition of "Dependence Constraints" in section 5.6.1.7,
where a preceding read dominates a subsequent write.

Such a dependence constraint admittedly does not impose a BEFORE (alpha
architecture term for globally visible ordering), but it does guarantee
that there can be no "causal loop".  I don't see how you could avoid
such a loop if another cpu could see the stored value and then impact
the value of the first read.  Put another way: the read and the write
could not be seen as being out of order wrt other cpus.

So I do not see how these "x_ctrl()" functions can currently be necessary.

I may have to eat my words at some point, but in the absense of clear
proof that alpha actually needs this, or indeed even an explanation of
how alpha could _possibly_ need it, I do not believe these functions are
called for.

And if it turns out that alpha really _does_ need a barrier for this
case, that barrier still should not be "smp_read_barrier_depends()".
We'd have to make up some new speciality barrier just for alpha, along
with the documentation for why it really is necessary.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul E McKenney <paulmck@us.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull locking changes from Ingo Molnar:
 "The main changes in this cycle were:

   - More gradual enhancements to atomic ops: new atomic*_read_ctrl()
     ops, synchronize atomic_{read,set}() ordering requirements between
     architectures, add atomic_long_t bitops.  (Peter Zijlstra)

   - Add _{relaxed|acquire|release}() variants for inc/dec atomics and
     use them in various locking primitives: mutex, rtmutex, mcs, rwsem.
     This enables weakly ordered architectures (such as arm64) to make
     use of more locking related optimizations.  (Davidlohr Bueso)

   - Implement atomic[64]_{inc,dec}_relaxed() on ARM.  (Will Deacon)

   - Futex kernel data cache footprint micro-optimization.  (Rasmus
     Villemoes)

   - pvqspinlock runtime overhead micro-optimization.  (Waiman Long)

   - misc smaller fixlets"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ARM, locking/atomics: Implement _relaxed variants of atomic[64]_{inc,dec}
  locking/rwsem: Use acquire/release semantics
  locking/mcs: Use acquire/release semantics
  locking/rtmutex: Use acquire/release semantics
  locking/mutex: Use acquire/release semantics
  locking/asm-generic: Add _{relaxed|acquire|release}() variants for inc/dec atomics
  atomic: Implement atomic_read_ctrl()
  atomic, arch: Audit atomic_{read,set}()
  atomic: Add atomic_long_t bitops
  futex: Force hot variables into a single cache line
  locking/pvqspinlock: Kick the PV CPU unconditionally when _Q_SLOW_VAL
  locking/osq: Relax atomic semantics
  locking/qrwlock: Rename ->lock to ->wait_lock
  locking/Documentation/lockstat: Fix typo - lokcing -> locking
  locking/atomics, cmpxchg: Privatize the inclusion of asm/cmpxchg.h

Pull RCU changes from Ingo Molnar:
 "The main changes in this cycle were:

   - Improvements to expedited grace periods (Paul E McKenney)

   - Performance improvements to and locktorture tests for percpu-rwsem
     (Oleg Nesterov, Paul E McKenney)

   - Torture-test changes (Paul E McKenney, Davidlohr Bueso)

   - Documentation updates (Paul E McKenney)

   - Miscellaneous fixes (Paul E McKenney, Boqun Feng, Oleg Nesterov,
     Patrick Marlier)"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
  fs/writeback, rcu: Don't use list_entry_rcu() for pointer offsetting in bdi_split_work_to_wbs()
  rcu: Better hotplug handling for synchronize_sched_expedited()
  rcu: Enable stall warnings for synchronize_rcu_expedited()
  rcu: Add tasks to expedited stall-warning messages
  rcu: Add online/offline info to expedited stall warning message
  rcu: Consolidate expedited CPU selection
  rcu: Prepare for consolidating expedited CPU selection
  cpu: Remove try_get_online_cpus()
  rcu: Stop excluding CPU hotplug in synchronize_sched_expedited()
  rcu: Stop silencing lockdep false positive for expedited grace periods
  rcu: Switch synchronize_sched_expedited() to IPI
  locktorture: Fix module unwind when bad torture_type specified
  torture: Forgive non-plural arguments
  rcutorture: Fix unused-function warning for torturing_tasks()
  rcutorture: Fix module unwind when bad torture_type specified
  rcu_sync: Cleanup the CONFIG_PROVE_RCU checks
  locking/percpu-rwsem: Clean up the lockdep annotations in percpu_down_read()
  locking/percpu-rwsem: Fix the comments outdated by rcu_sync
  locking/percpu-rwsem: Make use of the rcu_sync infrastructure
  locking/percpu-rwsem: Make percpu_free_rwsem() after kzalloc() safe
  ...

Pull EFI changes from Ingo Molnar:
 "The main changes in this cycle were:

   - further EFI code generalization to make it more workable for ARM64
   - various extensions, such as 64-bit framebuffer address support,
     UEFI v2.5 EFI_PROPERTIES_TABLE support
   - code modularization simplifications and cleanups
   - new debugging parameters
   - various fixes and smaller additions"

* 'core-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  efi: Fix warning of int-to-pointer-cast on x86 32-bit builds
  efi: Use correct type for struct efi_memory_map::phys_map
  x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled
  efi: Add "efi_fake_mem" boot option
  x86/efi: Rename print_efi_memmap() to efi_print_memmap()
  efi: Auto-load the efi-pstore module
  efi: Introduce EFI_NX_PE_DATA bit and set it from properties table
  efi: Add support for UEFIv2.5 Properties table
  efi: Add EFI_MEMORY_MORE_RELIABLE support to efi_md_typeattr_format()
  efifb: Add support for 64-bit frame buffer addresses
  efi/arm64: Clean up efi_get_fdt_params() interface
  arm64: Use core efi=debug instead of uefi_debug command line parameter
  efi/x86: Move efi=debug option parsing to core
  drivers/firmware: Make efi/esrt.c driver explicitly non-modular
  efi: Use the generic efi.memmap instead of 'memmap'
  acpi/apei: Use appropriate pgprot_t to map GHES memory
  arm64, acpi/apei: Implement arch_apei_get_mem_attributes()
  arm64/mm: Add PROT_DEVICE_nGnRnE and PROT_NORMAL_WT
  acpi, x86: Implement arch_apei_get_mem_attributes()
  efi, x86: Rearrange efi_mem_attributes()
  ...

Pull wchan kernel address hiding from Ingo Molnar:
 "This fixes a wchan related information leak in /proc/PID/stat.

  There's a bit of an ABI twist to it: instead of setting the wchan
  field to 0 (which is our usual technique) we set it conditionally to a
  0/1 flag to keep ABI compatibility with older procps versions that
  only fetches /proc/PID/wchan (symbolic names) if the absolute wchan
  address is nonzero"

* 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  fs/proc, core/debug: Don't expose absolute kernel addresses via wchan

Pull irq updates from Thomas Gleixner:
 "The irq departement delivers:

   - Rework the irqdomain core infrastructure to accomodate ACPI based
     systems.  This is required to support ARM64 without creating
     artificial device tree nodes.

   - Sanitize the ACPI based ARM GIC initialization by making use of the
     new firmware independent irqdomain core

   - Further improvements to the generic MSI management

   - Generalize the irq migration on CPU hotplug

   - Improvements to the threaded interrupt infrastructure

   - Allow the migration of "chained" low level interrupt handlers

   - Allow optional force masking of interrupts in disable_irq[_nosysnc]

   - Support for two new interrupt chips - Sigh!

   - A larger set of errata fixes for ARM gicv3

   - The usual pile of fixes, updates, improvements and cleanups all
     over the place"

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
  Document that IRQ_NONE should be returned when IRQ not actually handled
  PCI/MSI: Allow the MSI domain to be device-specific
  PCI: Add per-device MSI domain hook
  of/irq: Use the msi-map property to provide device-specific MSI domain
  of/irq: Split of_msi_map_rid to reuse msi-map lookup
  irqchip/gic-v3-its: Parse new version of msi-parent property
  PCI/MSI: Use of_msi_get_domain instead of open-coded "msi-parent" parsing
  of/irq: Use of_msi_get_domain instead of open-coded "msi-parent" parsing
  of/irq: Add support code for multi-parent version of "msi-parent"
  irqchip/gic-v3-its: Add handling of PCI requester id.
  PCI/MSI: Add helper function pci_msi_domain_get_msi_rid().
  of/irq: Add new function of_msi_map_rid()
  Docs: dt: Add PCI MSI map bindings
  irqchip/gic-v2m: Add support for multiple MSI frames
  irqchip/gic-v3: Fix translation of LPIs after conversion to irq_fwspec
  irqchip/mxs: Add Alphascale ASM9260 support
  irqchip/mxs: Prepare driver for hardware with different offsets
  irqchip/mxs: Panic if ioremap or domain creation fails
  irqdomain: Documentation updates
  irqdomain/msi: Use fwnode instead of of_node
  ...

Pull timer updates from Thomas Gleixner:
 "The timer departement provides:

   - More y2038 work in the area of ntp and pps.

   - Optimization of posix cpu timers

   - New time related selftests

   - Some new clocksource drivers

   - The usual pile of fixes, cleanups and improvements"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
  timeconst: Update path in comment
  timers/x86/hpet: Type adjustments
  clocksource/drivers/armada-370-xp: Implement ARM delay timer
  clocksource/drivers/tango_xtal: Add new timer for Tango SoCs
  clocksource/drivers/imx: Allow timer irq affinity change
  clocksource/drivers/exynos_mct: Use container_of() instead of this_cpu_ptr()
  clocksource/drivers/h8300_*: Remove unneeded memset()s
  clocksource/drivers/sh_cmt: Remove unneeded memset() in sh_cmt_setup()
  clocksource/drivers/em_sti: Remove unneeded memset()s
  clocksource/drivers/mediatek: Use GPT as sched clock source
  clockevents/drivers/mtk: Fix spurious interrupt leading to crash
  posix_cpu_timer: Reduce unnecessary sighand lock contention
  posix_cpu_timer: Convert cputimer->running to bool
  posix_cpu_timer: Check thread timers only when there are active thread timers
  posix_cpu_timer: Optimize fastpath_timer_check()
  timers, kselftest: Add 'adjtick' test to validate adjtimex() tick adjustments
  timers: Use __fls in apply_slack()
  clocksource: Remove return statement from void functions
  net: sfc: avoid using timespec
  ntp/pps: use y2038 safe types in pps_event_time
  ...

Pull ARM updates from Russell King:
 "In this ARM merge, we remove more lines than we add.  Changes include:

   - Enable imprecise aborts early, so that bus errors aren't masked
     until later in the boot.  This has the side effect that boot
     loaders which provoke these aborts can cause the kernel to crash
     early in boot, so we install a handler to report this event around
     the site where these are enabled.

   - Remove the buggy but impossible to enable cmpxchg syscall code.

   - Add unwinding annotations to some assembly code.

   - Add support for atomic half-word exchange for ARMv6k+.

   - Reduce ioremap() alignment for SMP/LPAE cases where we don't need
     the large alignment.

   - Addition of an "optimal" 3G configuration for systems with 1G of
     RAM.

   - Increase vmalloc space by 128M.

   - Constify some SMP operations structures, which have never been
     writable.

   - Improve ARMs dma_mmap() support for mapping DMA coherent mappings
     into userspace.

   - Fix to the NMI backtrace code in the IPI case on ARM where the
     failing CPU gets stuck for 10s waiting for its own IPI to be
     delivered.

   - Removal of legacy PM support from the AMBA bus driver.

   - Another fix for the previous fix of vdsomunge"

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (23 commits)
  ARM: 8449/1: fix bug in vdsomunge swab32 macro
  arm: add missing of_node_put
  ARM: 8447/1: catch pending imprecise abort on unmask
  ARM: 8446/1: amba: Remove unused callbacks for legacy system PM
  ARM: 8443/1: Adding support for atomic half word exchange
  ARM: clean up TWD after previous patch
  ARM: 8441/2: twd: Don't set CLOCK_EVT_FEAT_C3STOP unconditionally
  ARM: 8440/1: remove obsolete documentation
  ARM: make highpte an expert option
  ARM: 8433/1: add a VMSPLIT_3G_OPT config option
  ARM: 8439/1: Fix backtrace generation when IPI is masked
  ARM: 8428/1: kgdb: Fix registers on sleeping tasks
  ARM: 8427/1: dma-mapping: add support for offset parameter in dma_mmap()
  ARM: 8426/1: dma-mapping: add missing range check in dma_mmap()
  ARM: remove user cmpxchg syscall
  ARM: 8438/1: Add unwinding to __clear_user_std()
  ARM: 8436/1: hw_breakpoint: remove unnecessary header
  ARM: 8434/2: Revert "7655/1: smp_twd: make twd_local_timer_of_register() no-op for nosmp"
  ARM: 8432/1: move VMALLOC_END from 0xff000000 to 0xff800000
  ARM: 8430/1: use default ioremap alignment for SMP or LPAE
  ...

Pull ARC updates from Vineet Gupta:

 - Support for new MM features in ARCv2 cores (THP, PAE40) Some generic
   THP bits are touched - all ACKed by Kirill

 - Platform framework updates to prepare for EZChip arrival (still in works)

 - ARC Public Mailing list setup finally (linux-snps-arc@lists.infraded.org)

* tag 'arc-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (42 commits)
  ARC: mm: PAE40 support
  ARC: mm: PAE40: tlbex.S: Explicitify the size of pte_t
  ARC: mm: PAE40: switch to using phys_addr_t for physical addresses
  ARC: mm: HIGHMEM: populate high memory from DT
  ARC: mm: HIGHMEM: kmap API implementation
  ARC: mm: preps ahead of HIGHMEM support #2
  ARC: mm: preps ahead of HIGHMEM support
  ARC: mm: use generic macros _BITUL()/_AC()
  ARC: mm: Improve Duplicate PD Fault handler
  MAINTAINERS: Add public mailing list for ARC
  ARC: Ensure DT mem base is same as what kernel is built with
  ARC: boot: Non Master cpus only need to call EARLY_CPU_SETUP once
  ARCv2: smp: [plat-*]: No need to explicitly call mcip_init_smp()
  ARC: smp: Introduce smp hook @init_irq_cpu called for all cores
  ARC: smp: Rename platform hook @init_smp -> @init_cpu_smp
  ARCv2: smp: [plat-*]: No need to explicitly call mcip_init_early_smp()
  ARC: smp: Introduce smp hook @init_early_smp for Master core
  ARC: remove @init_time, @init_irq platform callbacks
  ARC: smp: irqchip: handle IPI as percpu irq like timer
  ARC: boot: Support Halt-on-reset and Run-on-reset SMP booting modes
  ...

Pull CRIS changes from Jesper Nilsson:
 "Mostly another batch of code removal due to move to standard
  frameworks for CRISv32, initial devicetree configuration for a couple
  of boards, and some small fixes for kgdb and time handling"

* tag 'cris-for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris:
  cris: Drop reference to get_cmos_time()
  CRIS: Drop code related to obsolete or unused kconfigs
  cris: time: Cleanup of persistent clock stuff
  cris: re-use helpers to dump data in hex format
  CRIS v32: remove old GPIO and LEDs code
  CRIS v32: remove I2C bitbanging driver
  CRIS v32: add ARTPEC-3 and P1343 device trees
  CRIS v32: dev88: add GPIO, LEDs, RTC, temp sensor
  CRIS: add dt-bindings symlink
  CRIS v32: increase NR_IRQS
  cris: arch-v10: kgdb: Add '__used' for static variable is_dyn_brkp
  cris: arch-v10: kgdb: Use BAR instead of DTP0 for register P12
  cris: kgdb: use native hex2bin

Pull avr32 update from Hans-Christian Noren Egtvedt.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/egtvedt/linux-avr32:
  avr32: atngw100: remove useless include

Pull m68k update from Geert Uytterhoeven.

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k/sun3: Use %pM format specifier to print ethernet address

Pull LED updates from Jacek Anaszewski:

 - Move the out-of-LED-tree led-sead3 driver to the LED subsystem.

 - Add 'invert' sysfs attribute to the heartbeat trigger.

 - Add Device Tree support to the leds-netxbig driver and add related DT
   nodes to the kirkwood-netxbig.dtsi and kirkwood-net5big.dts files.
   Remove static LED setup from the related board files.

 - Remove redundant brightness conversion operation from leds-netxbig.

 - Improve leds-bcm6328 driver: improve default-state handling, add more
   init configuration options, print invalid LED instead of warning only
   about maximum LED value.

 - Add a shutdown function for setting gpio-leds into off state when
   shutting down.

 - Fix DT flash timeout property naming in leds-aat1290.txt.

 - Switch to using devm prefixed version of led_classdev_register()
   (leds-cobalt-qube, leds-hp6xx, leds-ot200, leds-ipaq-micro,
   leds-netxbig, leds-locomo, leds-menf21bmc, leds-net48xx, leds-wrap).

 - Add missing of_node_put (leds-powernv, leds-bcm6358, leds-bcm6328,
   leds-88pm860x).

 - Coding style fixes and cleanups: led-class/led-core, leds-ipaq-micro.

* tag 'leds_for_4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds: (27 commits)
  leds: 88pm860x: add missing of_node_put
  leds: bcm6328: add missing of_node_put
  leds: bcm6358: add missing of_node_put
  powerpc/powernv: add missing of_node_put
  leds: leds-wrap.c: Use devm_led_classdev_register
  leds: aat1290: Fix property naming of flash-timeout-us
  leds: leds-net48xx: Use devm_led_classdev_register
  leds: leds-menf21bmc.c: Use devm_led_class_register
  leds: leds-locomo.c: Use devm_led_classdev_register
  leds: leds-gpio: add shutdown function
  Documentation: leds: update DT bindings for leds-bcm6328
  leds-bcm6328: add more init configuration options
  leds-bcm6328: simplify and improve default-state handling
  leds-bcm6328: print invalid LED
  leds: netxbig: set led_classdev max_brightness
  leds: netxbig: convert to use the devm_ functions
  ARM: mvebu: remove static LED setup for netxbig boards
  ARM: Kirkwood: add LED DT entries for netxbig boards
  leds: netxbig: add device tree binding
  leds: triggers: add invert to heartbeat
  ...

for_each_child_of_node performs an of_node_get on each iteration, so
a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// <smpl>
@@
local idexpression n;
expression e,r;
@@

 for_each_child_of_node(r,n) {
   ...
(
   of_node_put(n);
|
   e = n
|
+  of_node_put(n);
?  break;
)
   ...
 }
... when != n
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

for_each_available_child_of_node performs an of_node_get on each
iteration, so a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// <smpl>
@@
expression root,e;
local idexpression child;
@@

 for_each_available_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
(
   return child;
|
+  of_node_put(child);
?  return ...;
)
   ...
 }
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

for_each_available_child_of_node performs an of_node_get on each
iteration, so a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// <smpl>
@@
expression root,e;
local idexpression child;
@@

 for_each_available_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
(
   return child;
|
+  of_node_put(child);
?  return ...;
)
   ...
 }
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

for_each_child_of_node performs an of_node_get on each iteration, so
a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// <smpl>
@@
expression root,e;
local idexpression child;
@@

 for_each_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
(
   return child;
|
+  of_node_put(child);
?  return ...;
)
   ...
 }
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

Use of resource managed function devm_led_classdev_register to
make initialization path simpler. Also removed redundant remove
function.
Signed-off-by: Fida Mohammad <fmthoker@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

flash-timeout-us property name is changed to flash-max-timeout-us.
This patch fixes that name.
Signed-off-by: Ingi Kim <ingi2.kim@samsung.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

Use devm_led_classdev_register instead of led_classdev_register,
removing the redundant net48xx_led_remove function.
Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

Use resource-managed function devm_led_classdev_register instead
of led_classdev_register, consequently remove redundant
menf21bmc_led_remove function.
Also drop the unneeded label err_free_leds.
Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

Use resource managed function devm_led_classdev_register to make
initialisation path simpler.
Also removed redundant led_classdev_unregister function.
Signed-off-by: Fida Mohammad <fmthoker@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

add a shutdown function for setting the gpio-leds
into off state when shuting down.
Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

This patch adds latest DT bindings for leds-bcm6328 init register
configuration.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

This patch adds more init register configuration options:
- Serial LEDs multiplexing.
- Serial LEDs clock signal low/high polarity.
- Serial LEDs data signal low/high polarity.
- Serial LEDs shift direction inverted/normal.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

This patch simplifies and improves the code related to
default-state handling.
It also changes the code to power off the LEDs by default.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>