This patch fix the following sparse warning:

for file arch/x86/kvm/x86.c:
warning: Using plain integer as NULL pointer
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

While in L2, leave all #UD to L2 and do not try to emulate it. If L1 is
interested in doing this, it reports its interest via the exception
bitmap, and we never get into handle_exception of L0 anyway.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

For a very long time (since 2b3d2a20), the path handling a vmmcall
instruction of the guest on an Intel host only applied the patch but no
longer handled the hypercall. The reverse case, vmcall on AMD hosts, is
fine. As both em_vmcall and em_vmmcall actually have to do the same, we
can fix the issue by consolidating both into the same handler.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Another patch in my war on emulate_on_interception() use as a svm exit handler.

These were pulled out of a larger patch at the suggestion of Radim Krcmar, see
https://lkml.org/lkml/2015/2/25/559

Changes since v1:
	* fixed typo introduced after test, retested
Signed-off-by: NDavid Kaplan <david.kaplan@amd.com>
[separated out just cr_interception part from larger removal of
INTERCEPT_CR0_WRITE, forward ported, tested]
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Merge tag 'kvm-s390-next-20150306' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into queue

KVM: s390: Features and Fixes for 4.1 (kvm/next)

1. Several Fixes and enhancements
---------------------------------
- These 3 patches have cc stable:
b75f4c9a KVM: s390: Zero out current VMDB of STSI before including level3 data.
261520dc KVM: s390: fix handling of write errors in the tpi handler
15462e37 KVM: s390: reinjection of irqs can fail in the tpi handler

2. SIMD support the kernel part (introduced with z13)
-----------------------------------------------------
- two KVM-generic changes in kvm.h:
1. New capability that can be enabled: KVM_CAP_S390_VECTOR_REGISTERS
2. increased padding size for sync regs in struct kvm_run to clarify that
   sync regs can be larger than 1k. This is fine as this is the last
   element in the structure.

The KVM list should be CCed on changes for arch/x86/kernel/kvm.c
and arch/x86/kernel/kvmclock.c
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

No need to re-decode WBINVD since we know what it is from the intercept.
Signed-off-by: NDavid Kaplan <David.Kaplan@amd.com>
[extracted from larger unlrelated patch, forward ported, tested,style cleanup]
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Currently kvm_emulate() skips the instruction but kvm_emulate_* sometimes
don't.  The end reult is the caller ends up doing the skip themselves.
Let's make them consistant.
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

WARNING: Prefer [subsystem eg: netdev]_info([subsystem]dev, ... then
dev_info(dev, ... then pr_info(...  to printk(KERN_INFO ...
+   printk(KERN_INFO "kvm: exiting hardware virtualization\n");

WARNING: Prefer [subsystem eg: netdev]_err([subsystem]dev, ... then
dev_err(dev, ... then pr_err(...  to printk(KERN_ERR ...
+	printk(KERN_ERR "kvm: misc device register failed\n");
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

ERROR: code indent should use tabs where possible
+                                 const struct kvm_io_range *r2)$

WARNING: please, no spaces at the start of a line
+                                 const struct kvm_io_range *r2)$

This patch fixes this ERROR & WARNING to reduce noise when checking new
patches in kvm_main.c.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

WARNING: please, no space before tabs
+ * ^I^Ikvm->lock --> kvm->slots_lock --> kvm->irq_lock$

WARNING: please, no space before tabs
+^I^I * ^I- gfn_to_hva (kvm_read_guest, gfn_to_pfn)$

WARNING: please, no space before tabs
+^I^I * ^I- kvm_is_visible_gfn (mmu_check_roots)$

This patch fixes these warnings to reduce noise when checking new
patches in kvm_main.c.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

There are many Warnings like this:
WARNING: Missing a blank line after declarations
+	struct kvm_coalesced_mmio_zone zone;
+	r = -EFAULT;

This patch fixes these warnings to reduce noise when checking new
patches in kvm_main.c.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

WARNING: EXPORT_SYMBOL(foo); should immediately follow its
function/variable
+EXPORT_SYMBOL_GPL(gfn_to_page);

This patch fixes these warnings to reduce noise when checking new
patches in kvm_main.c.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

ERROR: do not initialise statics to 0 or NULL
+static int kvm_usage_count = 0;

The kvm_usage_count will be placed to .bss segment when linking, so
not need to set it to 0 here obviously.

This patch fixes this ERROR to reduce noise when checking new patches
in kvm_main.c.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

WARNING: labels should not be indented
+   out_free_irq_routing:

This patch fixes this WARNING to reduce noise when checking new patches
in kvm_main.c.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

There are many WARNINGs like this:
WARNING: sizeof tr should be sizeof(tr)
+	if (copy_from_user(&tr, argp, sizeof tr))

In kvm_main.c many places are using 'sizeof(X)', and the other places
are using 'sizeof X', while the kernel recommands to use 'sizeof(X)',
so this patch will replace all 'sizeof X' to 'sizeof(X)' to make them
consistent and at the same time to reduce the WARNINGs noise when we
are checking new patches.
Signed-off-by: NXiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

kvm_kvfree() provides exactly the same functionality as the
new common kvfree() function - so let's simply replace the
kvm function with the common function.
Signed-off-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

halt_poll_ns is used only locally. Make it static.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch fixes the bug discussed in
https://www.mail-archive.com/kvm@vger.kernel.org/msg109813.html

This patch uses a new field named irr_delivered to record the
delivery status of edge-triggered interrupts, and clears the
delivered interrupts in kvm_get_ioapic. So it has the same effect
of commit 0bc830b0
("KVM: ioapic: clear IRR for edge-triggered interrupts at delivery")
while avoids the bug of Windows guests.
Signed-off-by: NWincy Van <fanwenyi0529@gmail.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Fix whitespace around while
Signed-off-by: NKevin Mulvey <kmulvey@linux.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Better alignment of loop using tabs rather than spaces, this
makes checkpatch.pl happier.
Signed-off-by: NKevin Mulvey <kmulvey@linux.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

KVM has nice wrappers to access the register values, clean up a few places
that should use them but currently do not.
Signed-off-by: NDavid Kaplan <david.kaplan@amd.com>
[forward port and testing]
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Acked-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Pull kvm/s390 bugfixes from Marcelo Tosatti.

* git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: non-LPAR case obsolete during facilities mask init
  KVM: s390: include guest facilities in kvm facility test
  KVM: s390: fix in memory copy of facility lists
  KVM: s390/cpacf: Fix kernel bug under z/VM
  KVM: s390/cpacf: Enable key wrapping by default

Pull s390 fixes from Martin Schwidefsky:
 "One performance optimization for page_clear and a couple of bug fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/mm: fix incorrect ASCE after crst_table_downgrade
  s390/ftrace: fix crashes when switching tracers / add notrace to cpu_relax()
  s390/pci: unify pci_iomap symbol exports
  s390/pci: fix [un]map_resources sequence
  s390: let the compiler do page clearing
  s390/pci: fix possible information leak in mmio syscall
  s390/dcss: array index 'i' is used before limits check.
  s390/scm_block: fix off by one during cluster reservation
  s390/jump label: improve and fix sanity check
  s390/jump label: add missing jump_label_apply_nops() call

Merge tag 'trace-fixes-v4.0-rc2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull seq-buf/ftrace fixes from Steven Rostedt:
 "This includes fixes for seq_buf_bprintf() truncation issue.  It also
  contains fixes to ftrace when /proc/sys/kernel/ftrace_enabled and
  function tracing are started.  Doing the following causes some issues:

    # echo 0 > /proc/sys/kernel/ftrace_enabled
    # echo function_graph > /sys/kernel/debug/tracing/current_tracer
    # echo 1 > /proc/sys/kernel/ftrace_enabled
    # echo nop > /sys/kernel/debug/tracing/current_tracer
    # echo function_graph > /sys/kernel/debug/tracing/current_tracer

  As well as with function tracing too.  Pratyush Anand first reported
  this issue to me and supplied a patch.  When I tested this on my x86
  test box, it caused thousands of backtraces and warnings to appear in
  dmesg, which also caused a denial of service (a warning for every
  function that was listed).  I applied Pratyush's patch but it did not
  fix the issue for me.  I looked into it and found a slight problem
  with trampoline accounting.  I fixed it and sent Pratyush a patch, but
  he said that it did not fix the issue for him.

  I later learned tha Pratyush was using an ARM64 server, and when I
  tested on my ARM board, I was able to reproduce the same issue as
  Pratyush.  After applying his patch, it fixed the problem.  The above
  test uncovered two different bugs, one in x86 and one in ARM and
  ARM64.  As this looked like it would affect PowerPC, I tested it on my
  PPC64 box.  It too broke, but neither the patch that fixed ARM or x86
  fixed this box (the changes were all in generic code!).  The above
  test, uncovered two more bugs that affected PowerPC.  Again, the
  changes were only done to generic code.  It's the way the arch code
  expected things to be done that was different between the archs.  Some
  where more sensitive than others.

  The rest of this series fixes the PPC bugs as well"

* tag 'trace-fixes-v4.0-rc2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled
  ftrace: Fix en(dis)able graph caller when en(dis)abling record via sysctl
  ftrace: Clear REGS_EN and TRAMP_EN flags on disabling record via sysctl
  seq_buf: Fix seq_buf_bprintf() truncation
  seq_buf: Fix seq_buf_vprintf() truncation

Pull networking fixes from David Miller:

 1) nft_compat accidently truncates ethernet protocol to 8-bits, from
    Arturo Borrero.

 2) Memory leak in ip_vs_proc_conn(), from Julian Anastasov.

 3) Don't allow the space required for nftables rules to exceed the
    maximum value representable in the dlen field.  From Patrick
    McHardy.

 4) bcm63xx_enet can accidently leave interrupts permanently disabled
    due to errors in the NAPI polling exit logic.  Fix from Nicolas
    Schichan.

 5) Fix OOPSes triggerable by the ping protocol module, due to missing
    address family validations etc.  From Lorenzo Colitti.

 6) Don't use RCU locking in sleepable context in team driver, from Jiri
    Pirko.

 7) xen-netback miscalculates statistic offset pointers when reporting
    the stats to userspace.  From David Vrabel.

 8) Fix a leak of up to 256 pages per VIF destroy in xen-netaback, also
    from David Vrabel.

 9) ip_check_defrag() cannot assume that skb_network_offset(),
    particularly when it is used by the AF_PACKET fanout defrag code.
    From Alexander Drozdov.

10) gianfar driver doesn't query OF node names properly when trying to
    determine the number of hw queues available.  Fix it to explicitly
    check for OF nodes named queue-group.  From Tobias Waldekranz.

11) MID field in macb driver should be 12 bits, not 16.  From Punnaiah
    Choudary Kalluri.

12) Fix unintentional regression in traceroute due to timestamp socket
    option changes.  Empty ICMP payloads should be allowed in
    non-timestamp cases.  From Willem de Bruijn.

13) When devices are unregistered, we have to get rid of AF_PACKET
    multicast list entries that point to it via ifindex.  Fix from
    Francesco Ruggeri.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (38 commits)
  tipc: fix bug in link failover handling
  net: delete stale packet_mclist entries
  net: macb: constify macb configuration data
  MAINTAINERS: add Marc Kleine-Budde as co maintainer for CAN networking layer
  MAINTAINERS: linux-can moved to github
  can: kvaser_usb: Read all messages in a bulk-in URB buffer
  can: kvaser_usb: Avoid double free on URB submission failures
  can: peak_usb: fix missing ctrlmode_ init for every dev
  can: add missing initialisations in CAN related skbuffs
  ip: fix error queue empty skb handling
  bgmac: Clean warning messages
  tcp: align tcp_xmit_size_goal() on tcp_tso_autosize()
  net: fec: fix unbalanced clk disable on driver unbind
  net: macb: Correct the MID field length value
  net: gianfar: correctly determine the number of queue groups
  ipv4: ip_check_defrag should not assume that skb_network_offset is zero
  net: bcmgenet: properly disable password matching
  net: eth: xgene: fix booting with devicetree
  bnx2x: Force fundamental reset for EEH recovery
  xen-netback: refactor xenvif_handle_frag_list()
  ...

Pull input subsystem fixes from Dmitry Torokhov:
 "Miscellaneous driver fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: psmouse - disable "palm detection" in the focaltech driver
  Input: psmouse - disable changing resolution/rate/scale for FocalTech
  Input: psmouse - ensure that focaltech reports consistent coordinates
  Input: psmouse - remove hardcoded touchpad size from the focaltech driver
  Input: tc3589x-keypad - set IRQF_ONESHOT flag to ensure IRQ request
  Input: ALPS - fix memory leak when detection fails
  Input: sun4i-ts - add thermal driver dependency
  Input: cyapa - remove superfluous type check in cyapa_gen5_read_idac_data()
  Input: cyapa - fix unaligned functions redefinition error
  Input: mma8450 - add parent device

Pull regulator fixes from Mark Brown:
 "A couple of driver specific fixes plus a fix for a regression in the
  core where the updates to use sysfs group registration were overly
  enthusiastic in eliding properties and removed some that had been
  previously present"

* tag 'regulator-v4.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: Fix regression due to NULL constraints check
  regulator: rk808: Set the enable time for LDOs
  regulator: da9210: Mask all interrupt sources to deassert interrupt line

Pull spi fixes from Mark Brown:
 "A collection of driver specific fixes to which the usual comments
  about them being important if you see them mostly apply (except for
  the comment fix).  The pl022 one is particularly nasty for anyone
  affected by it"

* tag 'spi-v4.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: pl022: Fix race in giveback() leading to driver lock-up
  spi: dw-mid: avoid potential NULL dereference
  spi: img-spfi: Verify max spfi transfer length
  spi: fix a typo in comment.
  spi: atmel: Fix interrupt setup for PDC transfers
  spi: dw: revisit FIFO size detection again
  spi: dw-pci: correct number of chip selects
  drivers: spi: ti-qspi: wait for busy bit clear before data write/read

Pull tpm fixes from James Morris:
 "fixes for the TPM driver"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  tpm: fix call order in tpm-chip.c
  tpm/ibmvtpm: Additional LE support for tpm_ibmvtpm_send

Pull fbdev fixes from Tomi Valkeinen:
 - Fix regression in with omapdss when using i2c displays
 - Fix possible null deref in fbmon
 - Check kalloc return value in AMBA CLCD

* tag 'fbdev-fixes-4.0' of git://git.kernel.org/pub/scm/linux/kernel/git/tomba/linux:
  OMAPDSS: fix regression with display sysfs files
  video: fbdev: fix possible null dereference
  video: ARM CLCD: Add missing error check for devm_kzalloc

Pull cgroup fixes from Tejun Heo:
 "The cgroup iteration update two years ago and the recent cpuset
  restructuring introduced regressions in subset of cpuset
  configurations.  Three patches to fix them.

  All are marked for -stable"

* 'for-4.0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: Fix cpuset sched_relax_domain_level
  cpuset: fix a warning when clearing configured masks in old hierarchy
  cpuset: initialize effective masks when clone_children is enabled

Pull libata fixlet from Tejun Heo:
 "Speed limiting fix for sata_fsl"

* 'for-4.0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  sata-fsl: Apply link speed limits

Pull workqueue fix from Tejun Heo:
 "One fix patch for a subtle livelock condition which can happen on
  PREEMPT_NONE kernels involving two racing cancel_work calls.  Whoever
  comes in the second has to wait for the previous one to finish.  This
  was implemented by making the later one block for the same condition
  that the former would be (work item completion) and then loop and
  retest; unfortunately, depending on the wake up order, the later one
  could lock out the former one to finish by busy looping on the cpu.

  This is fixed by implementing explicit wait mechanism.  Work item
  might not belong anywhere at this point and there's remote possibility
  of thundering herd problem.  I originally tried to use bit_waitqueue
  but it didn't work for static work items on modules.  It's currently
  using single wait queue with filtering wake up function and exclusive
  wakeup.  If this ever becomes a problem, which is not very likely, we
  can try to figure out a way to piggy back on bit_waitqueue"

* 'for-4.0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: fix hang involving racing cancel[_delayed]_work_sync()'s for PREEMPT_NONE

In commit c637c103
("tipc: resolve race problem at unicast message reception") we
introduced a new mechanism for delivering buffers upwards from link
to socket layer.

That code contains a bug in how we handle the new link input queue
during failover. When a link is reset, some of its users may be blocked
because of congestion, and in order to resolve this, we add any pending
wakeup pseudo messages to the link's input queue, and deliver them to
the socket. This misses the case where the other, remaining link also
may have congested users. Currently, the owner node's reference to the
remaining link's input queue is unconditionally overwritten by the
reset link's input queue. This has the effect that wakeup events from
the remaining link may be unduely delayed (but not lost) for a
potentially long period.

We fix this by adding the pending events from the reset link to the
input queue that is currently referenced by the node, whichever one
it is.

This commit should be applied to both net and net-next.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When an interface is deleted from a net namespace the ifindex in the
corresponding entries in PF_PACKET sockets' mclists becomes stale.
This can create inconsistencies if later an interface with the same ifindex
is moved from a different namespace (not that unlikely since ifindexes are
per-namespace).
In particular we saw problems with dev->promiscuity, resulting
in "promiscuity touches roof, set promiscuity failed. promiscuity
feature of device might be broken" warnings and EOVERFLOW failures of
setsockopt(PACKET_ADD_MEMBERSHIP).
This patch deletes the mclist entries for interfaces that are deleted.
Since this now causes setsockopt(PACKET_DROP_MEMBERSHIP) to fail with
EADDRNOTAVAIL if called after the interface is deleted, also make
packet_mc_drop not fail.
Signed-off-by: NFrancesco Ruggeri <fruggeri@arista.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The configurations are not modified by the driver.  Make them 'const' so
that they may be placed in a read-only section.
Signed-off-by: NJosh Cartwright <joshc@ni.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Merge tag 'linux-can-fixes-for-4.0-20150309' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2015-03-09

this is a pull request for net/master for the 4.0 release cycle, it consists of
6 patches:

A patch by Oliver Hartkopp fixes a long outstanding bug in the infrastructure,
which leads to skb_under_panics when CAN interfaces are used by AF_PACKET
sockets e.g. by dhclient. Stephane Grosjean contributes a patch for the
peak_usb driver which adds a missing initialization. Two patches by Ahmed S.
Darwish fix problems in the kvaser_usb driver. Followed by two patches by
myself, updating the MAINTAINERS file
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some archs (specifically PowerPC), are sensitive with the ordering of
the enabling of the calls to function tracing and setting of the
function to use to be traced.

That is, update_ftrace_function() sets what function the ftrace_caller
trampoline should call. Some archs require this to be set before
calling ftrace_run_update_code().

Another bug was discovered, that ftrace_startup_sysctl() called
ftrace_run_update_code() directly. If the function the ftrace_caller
trampoline changes, then it will not be updated. Instead a call
to ftrace_startup_enable() should be called because it tests to see
if the callback changed since the code was disabled, and will
tell the arch to update appropriately. Most archs do not need this
notification, but PowerPC does.

The problem could be seen by the following commands:

 # echo 0 > /proc/sys/kernel/ftrace_enabled
 # echo function > /sys/kernel/debug/tracing/current_tracer
 # echo 1 > /proc/sys/kernel/ftrace_enabled
 # cat /sys/kernel/debug/tracing/trace

The trace will show that function tracing was not active.

Cc: stable@vger.kernel.org # 2.6.27+
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

When ftrace is enabled globally through the proc interface, we must check if
ftrace_graph_active is set. If it is set, then we should also pass the
FTRACE_START_FUNC_RET command to ftrace_run_update_code(). Similarly, when
ftrace is disabled globally through the proc interface, we must check if
ftrace_graph_active is set. If it is set, then we should also pass the
FTRACE_STOP_FUNC_RET command to ftrace_run_update_code().

Consider the following situation.

 # echo 0 > /proc/sys/kernel/ftrace_enabled

After this ftrace_enabled = 0.

 # echo function_graph > /sys/kernel/debug/tracing/current_tracer

Since ftrace_enabled = 0, ftrace_enable_ftrace_graph_caller() is never
called.

 # echo 1 > /proc/sys/kernel/ftrace_enabled

Now ftrace_enabled will be set to true, but still
ftrace_enable_ftrace_graph_caller() will not be called, which is not
desired.

Further if we execute the following after this:
  # echo nop > /sys/kernel/debug/tracing/current_tracer

Now since ftrace_enabled is set it will call
ftrace_disable_ftrace_graph_caller(), which causes a kernel warning on
the ARM platform.

On the ARM platform, when ftrace_enable_ftrace_graph_caller() is called,
it checks whether the old instruction is a nop or not. If it's not a nop,
then it returns an error. If it is a nop then it replaces instruction at
that address with a branch to ftrace_graph_caller.
ftrace_disable_ftrace_graph_caller() behaves just the opposite. Therefore,
if generic ftrace code ever calls either ftrace_enable_ftrace_graph_caller()
or ftrace_disable_ftrace_graph_caller() consecutively two times in a row,
then it will return an error, which will cause the generic ftrace code to
raise a warning.

Note, x86 does not have an issue with this because the architecture
specific code for ftrace_enable_ftrace_graph_caller() and
ftrace_disable_ftrace_graph_caller() does not check the previous state,
and calling either of these functions twice in a row has no ill effect.

Link: http://lkml.kernel.org/r/e4fbe64cdac0dd0e86a3bf914b0f83c0b419f146.1425666454.git.panand@redhat.com

Cc: stable@vger.kernel.org # 2.6.31+
Signed-off-by: NPratyush Anand <panand@redhat.com>
[
  removed extra if (ftrace_start_up) and defined ftrace_graph_active as 0
  if CONFIG_FUNCTION_GRAPH_TRACER is not set.
]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>