We can enable/disable timer statistics collection via:

  echo [1|0] > /proc/timers_stats

and it would be nice if apps had the ability to check
what the current collection status is.

This patch adds a 'Collection: active/inactive' line to display the
current timer collection status.

Also bump up the timer stats version to v0.3.
Signed-off-by: Dong Zhu <bluezhudong@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20131010075618.GH2139@zhudong.nay.redhat.com
[ Improved the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Pull more timekeeping items for v3.13 from John Stultz:

  * Small cleanup in the clocksource code.

  * Fix for rtc-pl031 to let it work with alarmtimers.

  * Move arm64 to using the generic sched_clock framework & resulting
    cleanup in the generic sched_clock code.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Nobody is using sched_clock_func() anymore now that sched_clock
supports up to 64 bits. Remove the hook so that new code only
uses sched_clock_register().
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

Register with the generic sched_clock framework now that it
supports 64 bits. This fixes two problems with the current
sched_clock support for machines using the architected timers.
First off, we don't subtract the start value from subsequent
sched_clock calls so we can potentially start off with
sched_clock returning gigantic numbers. Second, there is no
support for suspend/resume handling so problems such as discussed
in 6a4dae5e (ARM: 7565/1: sched: stop sched_clock() during
suspend, 2012-10-23) can happen without this patch. Finally, it
allows us to move the sched_clock setup into drivers clocksource
out of the arch ports.

Cc: Christopher Covington <cov@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

Pull ARM clocksource/clockevents updates from Daniel Lezcano:

  * Will Deacon and Sudeep KarkadaNagesha implemented the event stream
    for architected timer. The event streams can be used to impose a
    timeout on a wfe, to safeguard against any programming error in case
    an expected event is not generated or even to implement wfe-based
    timeouts for userspace locking implementations. Some files fall
    under the arm maintainers' umbrella but those changes have been
    reviewed and acked by the relevant people (Catalin Marinas and Olof
    Johansson).

  * Boris Brezillon improved the tcb_clksrc driver by removing a
    deprecated flag, checking return code values and using functions
    from the common clock framework.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Remove the deprecated IRQF_DISABLED flag.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Check function return values to avoid false positive driver init.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Replace clk_enable/disable with clk_prepare_enable/disable_unprepare to
avoid common clk framework warnings.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Adds support to configure the rate and enable the event stream for architected
timer. The event streams can be used to impose a timeout on a wfe, to safeguard
against any programming error in case an expected event is not generated or
even to implement wfe-based timeouts for userspace locking implementations.
This feature can be disabled(enabled by default).

Since the timer control register is reset to zero on warm boot, CPU PM notifier
is added to save and restore the value.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Pull (mostly) ARM clocksource driver updates from Daniel Lezcano:

" - Soren Brinkmann added FEAT_PERCPU to a clock device when it is local
    per cpu. This feature prevents the clock framework to choose a per cpu
    timer as a broadcast timer. This problem arised when the ARM global
    timer is used when switching to the broadcast timer which is the case
    now on Xillinx with its cpuidle driver.

  - Stephen Boyd extended the generic sched_clock code to support 64bit
    counters and removes the setup_sched_clock deprecation, as that causes
    lots of warnings since there's still users in the arch/arm tree. He
    added also the CLOCK_SOURCE_SUSPEND_NONSTOP flag on the architected
    timer as they continue counting during suspend.

  - Uwe Kleine-König added some missing __init sections and consolidated the
    code by moving the of_node_put call from the drivers to the function
    clocksource_of_init. "
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge branch 'timers/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core

Merge updated full dynticks support from Frederic Weisbecker:

   - support 32-bit systems (full dynticks was 64-bit only before)
   - support ARM
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge Linux 3.12-rc3 - refresh the tree with the latest fixes before merging new bits.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The ARM architected timers keep counting during suspend so we can
mark this clocksource with the CLOCK_SOURCE_SUSPEND_NONSTOP flag.
This flag will indicate that this clocksource can be used for
calculating suspend time and injecting sleep time into the
timekeeping core. This should be more accurate than using an
external RTC or architecture specific persistent clock.

Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

These are all only called by dw_apb_timer_init which is an __init
function, too
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Instead of letting each driver call of_node_put do it centrally in the
loop that also calls the CLOCKSOURCE_OF_DECLARE callbacks. This is less
prone to error and also moves getting and putting the references into the
same function.

Consequently all respective of_node_put calls in drivers are removed.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: David Brown <davidb@codeaurora.org>

Zynq is based on an ARM Cortex-A9 MPCore, which features the
arm_global_timer in its SCU. Therefore enable the timer for Zynq.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>

On most ARM systems the per-cpu clockevents are truly per-cpu in
the sense that they can't be controlled on any other CPU besides
the CPU that they interrupt. If one of these clockevents were to
become a broadcast source we will run into a lot of trouble
because the broadcast source is enabled on the first CPU to go
into deep idle (if that CPU suffers from FEAT_C3_STOP) and that
could be a different CPU than what the clockevent is interrupting
(or even worse the CPU that the clockevent interrupts could be
offline).

Theoretically it's possible to support per-cpu clockevents as the
broadcast source but so far we haven't needed this and supporting
it is rather complicated. Let's just deny the possibility for now
until this becomes a reality (let's hope it never does!).
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>

The arm_global_timer is a per cpu device. Set the appropriate flag.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>

Add the flag CLOCK_EVT_FEAT_PERCPU which is supposed to be set for per
cpu clockevent devices.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>

With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN,
allow ARM platforms to enable it.  Since VIRT_CPU_ACCOUNTING_GEN is a
dependency for full NO_HZ, this allows ARM platforms to enable full
NO_HZ as well.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arm Linux <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

The CONFIG_64BIT requirement on vtime can finally be removed
since we now depend on HAVE_VIRT_CPU_ACCOUNTING_GEN which
already takes care of the arch ability to handle nsecs based
cputime_t safely.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arm Linux <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. In order
to use that feature, arch code should be audited to ensure there are no
races in concurrent read/write of cputime_t. For example,
reading/writing 64-bit cputime_t on some 32-bit arches may require
multiple accesses for low and high value parts, so proper locking
is needed to protect against concurrent accesses.

Therefore, add CONFIG_HAVE_VIRT_CPU_ACCOUNTING_GEN which arches can
enable after they've been audited for potential races.

This option is automatically enabled on 64-bit platforms.

Feature requested by Frederic Weisbecker.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arm Linux <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

Pull USB fixes from Greg KH:
 "Here are a number of USB driver fixes for 3.12-rc3.

  These are all for host controller issues that have been reported, and
  there's a fix for an annoying error message that gets printed every
  time you remove a USB 3 device from the system that's been bugging me
  for a while"

* tag 'usb-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: dwc3: add support for Merrifield
  USB: fsl/ehci: fix failure of checking PHY_CLK_VALID during reinitialization
  USB: Fix breakage in ffs_fs_mount()
  fsl/usb: Resolve PHY_CLK_VLD instability issue for ULPI phy
  usb/core/devio.c: Don't reject control message to endpoint with wrong direction bit
  usb: chipidea: USB_CHIPIDEA should depend on HAS_DMA
  usb: chipidea: udc: free pending TD at removal procedure
  usb: chipidea: imx: Add usb_phy_shutdown at probe's error path
  usb: chipidea: Fix memleak for ci->hw_bank.regmap when removal
  usb: chipidea: udc: fix the oops after rmmod gadget
  USB: fix PM config symbol in uhci-hcd, ehci-hcd, and xhci-hcd
  USB: OHCI: accept very late isochronous URBs
  USB: UHCI: accept very late isochronous URBs
  USB: iMX21: accept very late isochronous URBs
  usbcore: check usb device's state before sending a Set SEL control transfer
  xhci: Fix race between ep halt and URB cancellation
  usb: Fix xHCI host issues on remote wakeup.
  xhci: Ensure a command structure points to the correct trb on the command ring
  xhci: Fix oops happening after address device timeout

Pull tty/serial fixes from Greg KH:
 "Here are some serial at tty driver fixes for 3.12-rc3

  The serial driver fixes some kref leaks, documentation is moved to the
  proper places, and the tty and n_tty fixes resolve some reported
  regressions.  There is still one outstanding tty regression fix that
  isn't in here yet, as I want to test it out some more, it will be sent
  for 3.12-rc4 if it checks out"

* tag 'tty-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: ar933x_uart: move devicetree binding documentation
  tty: Fix SIGTTOU not sent with tcflush()
  n_tty: Fix EOF push index when termios changes
  serial: pch_uart: remove unnecessary tty_port_tty_get
  serial: pch_uart: fix tty-kref leak in dma-rx path
  serial: pch_uart: fix tty-kref leak in rx-error path
  serial: tegra: fix tty-kref leak

Pull staging fixes from Greg KH:
 "Here are some staging driver fixes, MAINTAINER updates, and a new
  device id.  All of these have been in the linux-next tree, and are
  pretty simple patches"

* tag 'staging-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: r8188eu: Add new device ID
  staging: imx-drm: Fix probe failure
  staging: vt6656: [BUG] iwctl_siwencodeext return if device not open
  staging: vt6656: [BUG] main_usb.c oops on device_close move flag earlier.
  staging: vt6656: rxtx.c [BUG] s_vGetFreeContext dead lock on null apTD.
  Staging: rtl8192u: r819xU_cmdpkt: checking NULL value after doing dev_alloc_skb
  staging: usbip: Orphan usbip
  staging: r8188eu: Add files for new drive: Cocci spatch "noderef"
  staging: r8188eu: Cocci spatch "noderef"
  staging: octeon-usb: Cocci spatch "noderef"
  staging: r8188eu: Add files for new drive: Cocci spatch "noderef"
  MAINTAINERS: staging: dgnc and dgap drivers: add maintainer
  staging: lustre: Cocci spatch "noderef"

Merge tag 'driver-core-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core / sysfs fixes from Greg KH:
 "Here are 2 fixes for 3.12-rc3.  One fixes a sysfs problem with
  mounting caused by 3.12-rc1, and the other is a bug reported by the
  chromeos developers with the driver core.

  Both have been in linux-next for a bit"

* tag 'driver-core-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  driver core : Fix use after free of dev->parent in device_shutdown
  sysfs: Allow mounting without CONFIG_NET

Pull char/misc driver fixes from Greg KH:
 "Here are some HyperV and MEI driver fixes for 3.12-rc3.  They resolve
  some issues that people have been reporting for them"

* tag 'char-misc-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  Drivers: hv: vmbus: Terminate vmbus version negotiation on timeout
  Drivers: hv: util: Correctly support ws2008R2 and earlier
  mei: cancel stall timers in mei_reset
  mei: bus: stop wait for read during cl state transition
  mei: make me client counters less error prone

Pull perf revert from Ingo Molnar:
 "This fixes the 'perf top' regression Markus Trippelsdorf reported"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "perf symbols: Demangle cloned functions"

Pull drm fixes from Dave Airlie:
 "Nothing too major, radeon still has some dpm changes for off by
  default.

  Radeon, intel, msm:
   - radeon: a few more dpm fixes (still off by default), uvd fixes
   - i915: runtime warn backtrace and regression fix
   - msm: iommu changes fallout"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (27 commits)
  drm/msm: use drm_gem_dumb_destroy helper
  drm/msm: deal with mach/iommu.h removal
  drm/msm: Remove iommu include from mdp4_kms.c
  drm/msm: Odd PTR_ERR usage
  drm/i915: Fix up usage of SHRINK_STOP
  drm/radeon: fix hdmi audio on DCE3.0/3.1 asics
  drm/i915: preserve pipe A quirk in i9xx_set_pipeconf
  drm/i915/tv: clear adjusted_mode.flags
  drm/i915/dp: increase i2c-over-aux retry interval on AUX DEFER
  drm/radeon/cik: fix overflow in vram fetch
  drm/radeon: add missing hdmi callbacks for rv6xx
  drm/i915: Use a temporary va_list for two-pass string handling
  drm/radeon/uvd: lower msg&fb buffer requirements on UVD3
  drm/radeon: disable tests/benchmarks if accel is disabled
  drm/radeon: don't set default clocks for SI when DPM is disabled
  drm/radeon/dpm/ci: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/si: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/ni: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/btc: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm: fetch the max clk from voltage dep tables helper
  ...

This reverts commit de95ab53.

Markus Trippelsdorf reported that this commit broke 'perf top':

 > I just see a gray screen with no text at all. Sometimes the
 > following error messages are printed:
 >
 >  *** Error in `perf': invalid fastbin entry (free): 0x00000000029b18c0
 >  ***
 >  *** Error in `perf': malloc(): memory corruption (fast): 0x0000000000ee0b10 ***

While this code is fixable, the commit itself fails on several levels:

 - it should have been a separate helper function
 - why the heck does it do strchr() twice
 - it casts a const char * over into char *
 - sloppy style
 - it's not even a regression fix!

So lets revert it and re-try the patch in v3.13.
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

A small fix + deal with fallout of iommu changes + use new
drm_gem_dumb_destroy helper.

* 'msm-fixes-3.12-rc2' of git://people.freedesktop.org/~robclark/linux:
  drm/msm: use drm_gem_dumb_destroy helper
  drm/msm: deal with mach/iommu.h removal
  drm/msm: Remove iommu include from mdp4_kms.c
  drm/msm: Odd PTR_ERR usage

Merge branches 'sched-urgent-for-linus', 'timers-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler, timer and x86 fixes from Ingo Molnar:
 - A context tracking ARM build and functional fix
 - A handful of ARM clocksource/clockevent driver fixes
 - An AMD microcode patch level sysfs reporting fixlet

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  arm: Fix build error with context tracking calls

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource: em_sti: Set cpu_possible_mask to fix SMP broadcast
  clocksource: of: Respect device tree node status
  clocksource: exynos_mct: Set IRQ affinity when the CPU goes online
  arm: clocksource: mvebu: Use the main timer as clock source from DT

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode/AMD: Fix patch level reporting for family 15h

Pull perf fixes from Ingo Molnar:
 "A couple of tooling fixlets and a PMU detection printout fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: Fix PMU detection printout when no PMU is detected
  perf symbols: Demangle cloned functions
  perf machine: Fix path unpopulated in machine__create_modules()
  perf tools: Explicitly add libdl dependency
  perf probe: Fix probing symbols with optimization suffix
  perf trace: Add mmap2 handler
  perf kmem: Make it work again on non NUMA machines

Pull xfs bugfixes from Ben Myers:
 - fix for directory node collapse regression
 - fix for recovery over stale on disk structures
 - fix for eofblocks ioctl
 - fix asserts in xfs_inode_free
 - lock the ail before removing an item from it

* tag 'xfs-for-linus-v3.12-rc3' of git://oss.sgi.com/xfs/xfs:
  xfs: fix node forward in xfs_node_toosmall
  xfs: log recovery lsn ordering needs uuid check
  xfs: fix XFS_IOC_FREE_EOFBLOCKS definition
  xfs: asserting lock not held during freeing not valid
  xfs: lock the AIL before removing the buffer item

Pull i2c fixes from Wolfram Sang:
 "Some driver bugfixes for the I2C subsystem"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: ismt: initialize DMA buffer
  i2c: designware: 10-bit addressing mode enabling if I2C_DYNAMIC_TAR_UPDATE is set
  i2c: mv64xxx: Do not use writel_relaxed()
  i2c: mv64xxx: Fix some build warnings
  i2c: s3c2410: fix clk_disable/clk_unprepare WARNings

Pull ACPI and power management fixes from Rafael Wysocki:
 "These fix one recent cpufreq regression, a few older bugs that may
  harm users and a kerneldoc typo.

  Specifics:

   1) After the recent locking changes in the cpufreq core it is
      possible to trigger BUG_ON(!policy) in lock_policy_rwsem_read() if
      cpufreq_get() is called before registering a cpufreq driver.  Fix
      from Viresh Kumar.

   2) If intel_pstate has been loaded already, it doesn't make sense to
      do anything in acpi_cpufreq_init() and moreover doing something in
      there in that case may be harmful, so make that function return
      immediately if another cpufreq driver is already present.  From
      Yinghai Lu.

   3) The ACPI IPMI driver sometimes attempts to acquire a mutex from
      interrupt context, which can be avoided by replacing that mutex
      with a spinlock.  From Lv Zheng.

   4) A NULL pointer may be dereferenced by the exynos5440 cpufreq
      driver if a memory allocation made by it fails.  Fix from Sachin
      Kamat.

   5) Hanjun Guo's commit fixes a typo in the kerneldoc comment
      documenting acpi_bus_unregister_driver()"

* tag 'pm+acpi-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / scan: fix typo in comments of acpi_bus_unregister_driver()
  cpufreq: exynos5440: Fix potential NULL pointer dereference
  cpufreq: check cpufreq driver is valid and cpufreq isn't disabled in cpufreq_get()
  acpi-cpufreq: skip loading acpi_cpufreq after intel_pstate
  ACPI / IPMI: Fix atomic context requirement of ipmi_msg_handler()

Ben Herrenschmidt found that commit 928bea96 ("PCI: Delay enabling
bridges until they're needed") breaks PCI in some powerpc environments.

The reason is that the PCIe port driver will call pci_enable_device() on
the bridge, so the device is enabled, but skips pci_set_master because
pcie_port_auto and no acpi on powerpc.

Because of that, pci_enable_bridge() later on (called as a result of the
child device driver doing pci_enable_device) will see the bridge as
already enabled and will not call pci_set_master() on it.

Fixed by add checking in pci_enable_bridge, and call pci_set_master
if driver skip that.

That will make the code more robot and wade off problem for missing
pci_set_master in drivers.
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull s390 lockref enablement from Heiko Carstens:
 "Enabling the new lockless lockref variant on s390 would have been
  trivial until Tony Luck added a cpu_relax() call into the
  CMPXCHG_LOOP(), with commit d472d9d9 ("lockref: Relax in cmpxchg
  loop")

  As already mentioned cpu_relax() is very expensive on s390 since it
  yields() the current virtual cpu.  So we are talking of several
  thousand cycles.  Considering this enabling the lockless lockref
  variant would contradict the intention of the new semantics.  And also
  some quick measurements show performance regressions of 50% and more.

  Simply removing the cpu_relax() call again seems also not very
  desireable since Waiman Long reported that for some workloads the call
  improved performance by 5%."

* 'lockref' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: enable ARCH_USE_CMPXCHG_LOCKREF
  lockref: use arch_mutex_cpu_relax() in CMPXCHG_LOOP()
  mutex: replace CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX with simple ifdef

Commit 6072ddc8 ("kernel: replace strict_strto*() with kstrto*()")
broke the handling of signed integer types, fix it.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Reported-by: Christian Kujau <lists@nerdbynature.de>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>