open/release operations require userspace transitions to keep track
of the open count and to perform any FS-specific setup.  However,
for some purely read-only FSs which don't need to perform any setup
at open/release time, we can avoid the performance overhead of
calling into userspace for open/release calls.

This patch adds the necessary support to the fuse kernel modules to prevent
open/release operations from hitting in userspace. When the client returns
ENOSYS, we avoid sending the subsequent release to userspace, and also
remember this so that future opens also don't trigger a userspace
operation.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

Various read operations (e.g. readlink, readdir) invalidate the cached
attrs for atime changes.  This patch adds a new function
'fuse_invalidate_atime', which checks for a read-only super block and
avoids the attr invalidation in that case.
Signed-off-by: Andrew Gallagher <andrewjcg@fb.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

As noticed by Coverity the "num != 0" condition never triggers.  Instead it
should check for a complete page.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

Having this struct in module memory could Oops when if the module is
unloaded while the buffer still persists in a pipe.

Since sock_pipe_buf_ops is essentially the same as fuse_dev_pipe_buf_steal
merge them into nosteal_pipe_buf_ops (this is the same as
default_pipe_buf_ops except stealing the page from the buffer is not
allowed).
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

Since commit 61b365a5 ("drm/nouveau: populate master subdev pointer
only when fully constructed"), the nouveau_mxm(bios) call will return
NULL, since it's still being called from the constructor.  Instead, pass
the mxm pointer via the unused data field.

See https://bugs.freedesktop.org/show_bug.cgi?id=73791Reported-by: Andreas Reis <andreas.reis@gmail.com>
Tested-by: Andreas Reis <andreas.reis@gmail.com>
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull last-minute ACPI fix from Rafael Wysocki:
 "This reverts a commit that causes the Alan Cox' ASUS T100TA to "crash
  and burn" during boot if the Baytrail pinctrl driver is compiled in"

* tag 'acpi-3.13-fixup' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "ACPI: Add BayTrail SoC GPIO and LPSS ACPI IDs"

Pull perf fixes from Ingo Molnar:

 - an s2ram related fix on AMD systems

 - a perf fault handling bug that is relatively old but which has become
   much easier to trigger in v3.13 after commit e00b12e6 ("perf/x86:
   Further optimize copy_from_user_nmi()")

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/amd/ibs: Fix waking up from S3 for AMD family 10h
  x86, mm, perf: Allow recursive faults from interrupts

This reverts commit f6308b36 (ACPI: Add BayTrail SoC GPIO and LPSS
ACPI IDs), because it causes the Alan Cox' ASUS T100TA to "crash and
burn" during boot if the Baytrail pinctrl driver is compiled in.

Fixes: f6308b36 (ACPI: Add BayTrail SoC GPIO and LPSS ACPI IDs)
Reported-by: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Requested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull networking fixes from David Miller:

 1) The value choosen for the new SO_MAX_PACING_RATE socket option on
    parisc was very poorly choosen, let's fix it while we still can.
    From Eric Dumazet.

 2) Our generic reciprocal divide was found to handle some edge cases
    incorrectly, part of this is encoded into the BPF as deep as the JIT
    engines themselves.  Just use a real divide throughout for now.
    From Eric Dumazet.

 3) Because the initial lookup is lockless, the TCP metrics engine can
    end up creating two entries for the same lookup key.  Fix this by
    doing a second lookup under the lock before we actually create the
    new entry.  From Christoph Paasch.

 4) Fix scatter-gather list init in usbnet driver, from Bjørn Mork.

 5) Fix unintended 32-bit truncation in cxgb4 driver's bit shifting.
    From Dan Carpenter.

 6) Netlink socket dumping uses the wrong socket state for timewait
    sockets.  Fix from Neal Cardwell.

 7) Fix netlink memory leak in ieee802154_add_iface(), from Christian
    Engelmayer.

 8) Multicast forwarding in ipv4 can overflow the per-rule reference
    counts, causing all multicast traffic to cease.  Fix from Hannes
    Frederic Sowa.

 9) via-rhine needs to stop all TX queues when it resets the device,
    from Richard Weinberger.

10) Fix RDS per-cpu accesses broken by the this_cpu_* conversions.  From
    Gerald Schaefer.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  s390/bpf,jit: fix 32 bit divisions, use unsigned divide instructions
  parisc: fix SO_MAX_PACING_RATE typo
  ipv6: simplify detection of first operational link-local address on interface
  tcp: metrics: Avoid duplicate entries with the same destination-IP
  net: rds: fix per-cpu helper usage
  e1000e: Fix compilation warning when !CONFIG_PM_SLEEP
  bpf: do not use reciprocal divide
  be2net: add dma_mapping_error() check for dma_map_page()
  bnx2x: Don't release PCI bars on shutdown
  net,via-rhine: Fix tx_timeout handling
  batman-adv: fix batman-adv header overhead calculation
  qlge: Fix vlan netdev features.
  net: avoid reference counter overflows on fib_rules in multicast forwarding
  dm9601: add USB IDs for new dm96xx variants
  MAINTAINERS: add virtio-dev ML for virtio
  ieee802154: Fix memory leak in ieee802154_add_iface()
  net: usbnet: fix SG initialisation
  inet_diag: fix inet_diag_dump_icsk() to use correct state for timewait sockets
  cxgb4: silence shift wrapping static checker warning

The s390 bpf jit compiler emits the signed divide instructions "dr" and "d"
for unsigned divisions.
This can cause problems: the dividend will be zero extended to a 64 bit value
and the divisor is the 32 bit signed value as specified A or X accumulator,
even though A and X are supposed to be treated as unsigned values.

The divide instrunctions will generate an exception if the result cannot be
expressed with a 32 bit signed value.
This is the case if e.g. the dividend is 0xffffffff and the divisor either 1
or also 0xffffffff (signed: -1).

To avoid all these issues simply use unsigned divide instructions.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

SO_MAX_PACING_RATE definition on parisc got a typo.
Its not too late to fix it, before 3.13 is official.

Fixes: 62748f32 ("net: introduce SO_MAX_PACING_RATE")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In commit 1ec047eb ("ipv6: introduce per-interface counter for
dad-completed ipv6 addresses") I build the detection of the first
operational link-local address much to complex. Additionally this code
now has a race condition.

Replace it with a much simpler variant, which just scans the address
list when duplicate address detection completes, to check if this is
the first valid link local address and send RS and MLD reports then.

Fixes: 1ec047eb ("ipv6: introduce per-interface counter for dad-completed ipv6 addresses")
Reported-by: Jiri Pirko <jiri@resnulli.us>
Cc: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Flavio Leitner <fbl@redhat.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

Because the tcp-metrics is an RCU-list, it may be that two
soft-interrupts are inside __tcp_get_metrics() for the same
destination-IP at the same time. If this destination-IP is not yet part of
the tcp-metrics, both soft-interrupts will end up in tcpm_new and create
a new entry for this IP.
So, we will have two tcp-metrics with the same destination-IP in the list.

This patch checks twice __tcp_get_metrics(). First without holding the
lock, then while holding the lock. The second one is there to confirm
that the entry has not been added by another soft-irq while waiting for
the spin-lock.

Fixes: 51c5d0c4 (tcp: Maintain dynamic metrics in local cache.)
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

commit ae4b46e9 "net: rds: use this_cpu_* per-cpu helper" broke per-cpu
handling for rds. chpfirst is the result of __this_cpu_read(), so it is
an absolute pointer and not __percpu. Therefore, __this_cpu_write()
should not operate on chpfirst, but rather on cache->percpu->first, just
like __this_cpu_read() did before.

Cc: <stable@vger.kernel.org> # 3.8+
Signed-off-byd Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull namespace fixes from Eric Biederman:
 "This is a set of 3 regression fixes.

  This fixes /proc/mounts when using "ip netns add <netns>" to display
  the actual mount point.

  This fixes a regression in clone that broke lxc-attach.

  This fixes a regression in the permission checks for mounting /proc
  that made proc unmountable if binfmt_misc was in use.  Oops.

  My apologies for sending this pull request so late.  Al Viro gave
  interesting review comments about the d_path fix that I wanted to
  address in detail before I sent this pull request.  Unfortunately a
  bad round of colds kept from addressing that in detail until today.
  The executive summary of the review was:

  Al: Is patching d_path really sufficient?
      The prepend_path, d_path, d_absolute_path, and __d_path family of
      functions is a really mess.

  Me: Yes, patching d_path is really sufficient.  Yes, the code is mess.
      No it is not appropriate to rewrite all of d_path for a regression
      that has existed for entirely too long already, when a two line
      change will do"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  vfs: Fix a regression in mounting proc
  fork:  Allow CLONE_PARENT after setns(CLONE_NEWPID)
  vfs: In d_path don't call d_dname on a mount point

Pull KVM fix from Paolo Bonzini:
 "Fix for a brown paper bag bug.  Thanks to Drew Jones for noticing"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: x86: fix apic_base enable check

Included change:
- properly compute the batman-adv header overhead. Such
  result is later used to initialize the hard_header_len
  member of the soft-interface netdev object
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull arm64 fix from Catalin Marinas:
 "Revert "arm64: Fix memory shareability attribute for ioremap_wc/cache"

  We noticed that it breaks ioremap (and earlyprintk) with 64K page
  configuration"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  Revert "arm64: Fix memory shareability attribute for ioremap_wc/cache"

Commit 74e72f89 ("lib/percpu_counter.c: fix __percpu_counter_add()")
looked very plausible, but its arithmetic was badly wrong: obvious once
you see the fix, but maddening to get there from the weird tmpfs ENOSPCs
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Fan Du <fan.du@windriver.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 7509963c (e1000e: Fix a compile flag mis-match for
suspend/resume) moved suspend and resume hooks to be available when
CONFIG_PM is set. However, it can be set even if CONFIG_PM_SLEEP is not set
causing following warnings to be emitted:

drivers/net/ethernet/intel/e1000e/netdev.c:6178:12: warning:
  	‘e1000_suspend’ defined but not used [-Wunused-function]

drivers/net/ethernet/intel/e1000e/netdev.c:6185:12: warning:
	‘e1000_resume’ defined but not used [-Wunused-function]

To fix this make the hooks to be available only when CONFIG_PM_SLEEP is set
and remove CONFIG_PM wrapping from driver ops because this is already
handled by SET_SYSTEM_SLEEP_PM_OPS() and SET_RUNTIME_PM_OPS().
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Dave Ertman <davidx.m.ertman@intel.com>
Cc: Aaron Brown <aaron.f.brown@intel.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This reverts commit 2f7dc602.

The above commit breaks the mapping type for Device memory because
pgprot_default already contains a Normal memory type. pgprot_default is
also not initialised early enough for earlyprintk resulting in an
inconsistent memory mapping with 64K PAGE_SIZE configuration.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Will Deacon <will.deacon@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>

On AMD family 10h we see following error messages while waking up from
S3 for all non-boot CPUs leading to a failed IBS initialization:

 Enabling non-boot CPUs ...
 smpboot: Booting Node 0 Processor 1 APIC 0x1
 [Firmware Bug]: cpu 1, try to use APIC500 (LVT offset 0) for vector 0x400, but the register is already in use for vector 0xf9 on another cpu
 perf: IBS APIC setup failed on cpu #1
 process: Switch to broadcast mode on CPU1
 CPU1 is up
 ...
 ACPI: Waking up from system sleep state S3

Reason for this is that during suspend the LVT offset for the IBS
vector gets lost and needs to be reinialized while resuming.

The offset is read from the IBSCTL msr. On family 10h the offset needs
to be 1 as offset 0 is used for the MCE threshold interrupt, but
firmware assings it for IBS to 0 too. The kernel needs to reprogram
the vector. The msr is a readonly node msr, but a new value can be
written via pci config space access. The reinitialization is
implemented for family 10h in setup_ibs_ctl() which is forced during
IBS setup.

This patch fixes IBS setup after waking up from S3 by adding
resume/supend hooks for the boot cpu which does the offset
reinitialization.

Marking it as stable to let distros pick up this fix.
Signed-off-by: Robert Richter <rric@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> v3.2..
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1389797849-5565-1-git-send-email-rric.net@gmail.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

Waiman managed to trigger a PMI while in a emulate_vsyscall() fault,
the PMI in turn managed to trigger a fault while obtaining a stack
trace. This triggered the sig_on_uaccess_error recursive fault logic
and killed the process dead.

Fix this by explicitly excluding interrupts from the recursive fault
logic.
Reported-and-Tested-by: Waiman Long <waiman.long@hp.com>
Fixes: e00b12e6 ("perf/x86: Further optimize copy_from_user_nmi()")
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140110200603.GJ7572@laptop.programming.kicks-ass.netSigned-off-by: Ingo Molnar <mingo@kernel.org>

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

Pull scheduler and timer fixes from Ingo Molnar:
 "Contains a fix for a scheduler bug that manifested itself as a 3D
  performance regression and a crash fix for the ARM Cadence TTC clock
  driver"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Calculate effective load even if local weight is 0

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource: cadence_ttc: Fix mutex taken inside interrupt context

Pull locking fixes from Ingo Molnar:
 "Two fixes from lockdep coverage of seqlocks, which fix deadlocks on
  lockdep-enabled ARM systems"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched_clock: Disable seqlock lockdep usage in sched_clock()
  seqlock: Use raw_ prefix instead of _no_lockdep

Pull hwmon fix from Guenter Roeck:
 "Fix attribute length problem in coretemp driver"

* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (coretemp) Fix truncated name of alarm attributes

Pull ARM fixes from Russell King:
 "Another few fixes for ARM, nothing major here"

* 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
  ARM: 7938/1: OMAP4/highbank: Flush L2 cache before disabling
  ARM: 7939/1: traps: fix opcode endianness when read from user memory
  ARM: 7937/1: perf_event: Silence sparse warning
  ARM: 7934/1: DT/kernel: fix arch_match_cpu_phys_id to avoid erroneous match
  Revert "ARM: 7908/1: mm: Fix the arm_dma_limit calculation"

Pull writeback fix from Wu Fengguang:
 "Fix data corruption on NFS writeback.

  It has been in linux-next for one month"

* tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: Fix data corruption on NFS

Pull i2c bugfix from Wolfram Sang.

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: Re-instate body of i2c_parent_is_i2c_adapter()

At first Jakub Zawadzki noticed that some divisions by reciprocal_divide
were not correct. (off by one in some cases)
http://www.wireshark.org/~darkjames/reciprocal-buggy.c

He could also show this with BPF:
http://www.wireshark.org/~darkjames/set-and-dump-filter-k-bug.c

The reciprocal divide in linux kernel is not generic enough,
lets remove its use in BPF, as it is not worth the pain with
current cpus.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Mircea Gherzan <mgherzan@gmail.com>
Cc: Daniel Borkmann <dxchgb@gmail.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Matt Evans <matt@ozlabs.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

The driver does not check value returned by dma_map_page. The patch
fixes this.

v2: Removed the bugfix for non-bug ;-) (thanks Sathya)
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Acked-by: Sathya Perla <Sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The bnx2x driver in its pci shutdown() callback releases its pci bars (in the
same manner it does during its pci remove() callback).
During a system reboot while VFs are enabled, its possible for the VF's remove
to be called (as a result of pci_disable_sriov()) after its shutdown callback
has already finished running; This will cause a paging request fault as the VF
tries to access the pci bar which it has previously released, crashing the
system.

This patch further differentiates the shutdown and remove callbacks, preventing the
pci release procedures from being called during shutdown.
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rhine_reset_task() misses to disable the tx scheduler upon reset,
this can lead to a crash if work is still scheduled while we're resetting
the tx queue.

Fixes:
[   93.591707] BUG: unable to handle kernel NULL pointer dereference at 0000004c
[   93.595514] IP: [<c119d10d>] rhine_napipoll+0x491/0x6
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: David S. Miller <davem@davemloft.net>

Batman-adv prepends a full ethernet header in addition to its own
header. This has to be reflected in the MTU calculation, especially
since the value is used to set dev->hard_header_len.

Introduced by 411d6ed9
("batman-adv: consider network coding overhead when calculating required mtu")
Reported-by: cmsv <cmsv@wirelesspt.net>
Reported-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

Commit e66d2ae7 moved the assignment
vcpu->arch.apic_base = value above a condition with
(vcpu->arch.apic_base ^ value), causing that check
to always fail. Use old_value, vcpu->arch.apic_base's
old value, in the condition instead.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Merge patches from Andrew Morton:
 "Six fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  lib/percpu_counter.c: fix __percpu_counter_add()
  crash_dump: fix compilation error (on MIPS at least)
  mm: fix crash when using XFS on loopback
  MIPS: fix blast_icache32 on loongson2
  MIPS: fix case mismatch in local_r4k_flush_icache_range()
  nilfs2: fix segctor bug that causes file system corruption

Pull late md fixes from Neil Brown:
 "Half a dozen md bug fixes.

  All of these fix real bugs the people have hit, and are tagged for
  -stable.  Sorry they are late ....  Christmas holidays and all that.
  Hopefully they can still squeak into 3.13"

* tag 'md/3.13-fixes' of git://neil.brown.name/md:
  md: fix problem when adding device to read-only array with bitmap.
  md/raid10: fix bug when raid10 recovery fails to recover a block.
  md/raid5: fix a recently broken BUG_ON().
  md/raid1: fix request counting bug in new 'barrier' code.
  md/raid10: fix two bugs in handling of known-bad-blocks.
  md/raid5: Fix possible confusion when multiple write errors occur.

Pull drm fixes from Dave Airlie:
 "One nouveau regression fix on older cards, i915 black screen fixes,
  and a revert for a strange G33 intel problem"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/nouveau: fix null ptr dereferences on some boards
  Revert "drm: copy mode type in drm_mode_connector_list_update()"
  drm/i915/bdw: make sure south port interrupts are enabled properly v2
  drm/i915: Don't grab crtc mutexes in intel_modeset_gem_init()
  drm/i915: fix DDI PLLs HW state readout code

__percpu_counter_add() may be called in softirq/hardirq handler (such
as, blk_mq_queue_exit() is typically called in hardirq/softirq handler),
so we need to call this_cpu_add()(irq safe helper) to update percpu
counter, otherwise counts may be lost.

This fixes the problem that 'rmmod null_blk' hangs in blk_cleanup_queue()
because of miscounting of request_queue->mq_usage_counter.

This patch is the v1 of previous one of "lib/percpu_counter.c:
disable local irq when updating percpu couter", and takes Andrew's
approach which may be more efficient for ARCHs(x86, s390) that
have optimized this_cpu_add().
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Fan Du <fan.du@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>