There's no reason to use atomic bitops for cgroup_subsys_state->flags,
cgroup_root->flags and various subsys_masks.  This patch updates those
to use bitwise and/or operations instead and converts them form
unsigned long to unsigned int.

This makes the fields occupy (marginally) smaller space and makes it
clear that they don't require atomicity.

This patch doesn't cause any behavior difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

Use pr_fmt and remove embedded prefixes.
Realign modified multi-line statements to open parenthesis.
Convert embedded function name to "%s: ", __func__
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

As suggested by scripts/checkpatch.pl, substitude all pr_warning()
with pr_warn().

No functional change.
Signed-off-by: NJianyu Zhan <nasa4836@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

6612f05b ("cgroup: unify pidlist and other file handling")
has removed the only user of cgroup_pidlist_seq_operations :
cgroup_pidlist_open().

This patch removes it.
Signed-off-by: NJianyu Zhan <nasa4836@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

1d5be6b2 ("cgroup: move module ref handling into
rebind_subsystems()") makes parse_cgroupfs_options() no longer takes
refcounts on subsystems.

And unified hierachy makes parse_cgroupfs_options not need to call
with cgroup_mutex held to protect the cgroup_subsys[].

So this patch removes BUG_ON() and the comment.  As the comment
doesn't contain useful information afterwards, the whole comment is
removed.
Signed-off-by: NJianyu Zhan <nasa4836@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

Unified hierarchy will be the new version of cgroup interface.  This
patch adds Documentation/cgroups/unified-hierarchy.txt which describes
the design and rationales of unified hierarchy.

v2: Grammatical updates as per Randy Dunlap's review.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>

cgroup users often need a way to determine when a cgroup's
subhierarchy becomes empty so that it can be cleaned up.  cgroup
currently provides release_agent for it; unfortunately, this mechanism
is riddled with issues.

* It delivers events by forking and execing a userland binary
  specified as the release_agent.  This is a long deprecated method of
  notification delivery.  It's extremely heavy, slow and cumbersome to
  integrate with larger infrastructure.

* There is single monitoring point at the root.  There's no way to
  delegate management of a subtree.

* The event isn't recursive.  It triggers when a cgroup doesn't have
  any tasks or child cgroups.  Events for internal nodes trigger only
  after all children are removed.  This again makes it impossible to
  delegate management of a subtree.

* Events are filtered from the kernel side.  "notify_on_release" file
  is used to subscribe to or suppress release event.  This is
  unnecessarily complicated and probably done this way because event
  delivery itself was expensive.

This patch implements interface file "cgroup.populated" which can be
used to monitor whether the cgroup's subhierarchy has tasks in it or
not.  Its value is 0 if there is no task in the cgroup and its
descendants; otherwise, 1, and kernfs_notify() notificaiton is
triggers when the value changes, which can be monitored through poll
and [di]notify.

This is a lot ligther and simpler and trivially allows delegating
management of subhierarchy - subhierarchy monitoring can block further
propgation simply by putting itself or another process in the root of
the subhierarchy and monitor events that it's interested in from there
without interfering with monitoring higher in the tree.

v2: Patch description updated as per Serge.

v3: "cgroup.subtree_populated" renamed to "cgroup.populated".  The
    subtree_ prefix was a bit confusing because
    "cgroup.subtree_control" uses it to denote the tree rooted at the
    cgroup sans the cgroup itself while the populated state includes
    the cgroup itself.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NSerge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: NLi Zefan <lizefan@huawei.com>
Cc: Lennart Poettering <lennart@poettering.net>

Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core into for-3.16

Pull in driver-core-next to receive kernfs_notify() updates which will
be used by the planned "cgroup.populated" implementation.
Signed-off-by: NTejun Heo <tj@kernel.org>

Support for uevent_helper, aka hotplug, is not required on many systems
these days but it can still be enabled via sysfs or sysctl.
Reported-by: NDarren Shepherd <darren.s.shepherd@gmail.com>
Signed-off-by: NMichael Marineau <mike@marineau.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

kernfs_notify() is used to indicate either new data is available or
the content of a file has changed.  It currently only triggers poll
which may not be the most convenient to monitor especially when there
are a lot to monitor.  Let's hook it up to fsnotify too so that the
events can be monitored via inotify too.

fsnotify_modify() requires file * but kernfs_notify() doesn't have any
specific file associated; however, we can walk all super_blocks
associated with a kernfs_root and as kernfs always associate one ino
with inode and one dentry with an inode, it's trivial to look up the
dentry associated with a given kernfs_node.  As any active monitor
would pin dentry, just looking up existing dentry is enough.  This
patch looks up the dentry associated with the specified kernfs_node
and generates events equivalent to fsnotify_modify().

Note that as fsnotify doesn't provide fsnotify_modify() equivalent
which can be called with dentry, kernfs_notify() directly calls
fsnotify_parent() and fsnotify().  It might be better to add a wrapper
in fsnotify.h instead.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, there's no way to find out which super_blocks are
associated with a given kernfs_root.  Let's implement it - the planned
inotify extension to kernfs_notify() needs it.

Make kernfs_super_info point back to the super_block and chain it at
kernfs_root->supers.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

cgroup is switching away from multiple hierarchies and will use one
unified default hierarchy where controllers can be dynamically enabled
and disabled per subtree.  The default hierarchy will serve as the
unified hierarchy to which all controllers are attached and a css on
the default hierarchy would need to also serve the tasks of descendant
cgroups which don't have the controller enabled - ie. the tree may be
collapsed from leaf towards root when viewed from specific
controllers.  This has been implemented through effective css in the
previous patches.

This patch finally implements dynamic subtree controller
enable/disable on the default hierarchy via a new knob -
"cgroup.subtree_control" which controls which controllers are enabled
on the child cgroups.  Let's assume a hierarchy like the following.

  root - A - B - C
               \ D

root's "cgroup.subtree_control" determines which controllers are
enabled on A.  A's on B.  B's on C and D.  This coincides with the
fact that controllers on the immediate sub-level are used to
distribute the resources of the parent.  In fact, it's natural to
assume that resource control knobs of a child belong to its parent.
Enabling a controller in "cgroup.subtree_control" declares that
distribution of the respective resources of the cgroup will be
controlled.  Note that this means that controller enable states are
shared among siblings.

The default hierarchy has an extra restriction - only cgroups which
don't contain any task may have controllers enabled in
"cgroup.subtree_control".  Combined with the other properties of the
default hierarchy, this guarantees that, from the view point of
controllers, tasks are only on the leaf cgroups.  In other words, only
leaf csses may contain tasks.  This rules out situations where child
cgroups compete against internal tasks of the parent, which is a
competition between two different types of entities without any clear
way to determine resource distribution between the two.  Different
controllers handle it differently and all the implemented behaviors
are ambiguous, ad-hoc, cumbersome and/or just wrong.  Having this
structural constraints imposed from cgroup core removes the burden
from controller implementations and enables showing one consistent
behavior across all controllers.

When a controller is enabled or disabled, css associations for the
controller in the subtrees of each child should be updated.  After
enabling, the whole subtree of a child should point to the new css of
the child.  After disabling, the whole subtree of a child should point
to the cgroup's css.  This is implemented by first updating cgroup
states such that cgroup_e_css() result points to the appropriate css
and then invoking cgroup_update_dfl_csses() which migrates all tasks
in the affected subtrees to the self cgroup on the default hierarchy.

* When read, "cgroup.subtree_control" lists all the currently enabled
  controllers on the children of the cgroup.

* White-space separated list of controller names prefixed with either
  '+' or '-' can be written to "cgroup.subtree_control".  The ones
  prefixed with '+' are enabled on the controller and '-' disabled.

* A controller can be enabled iff the parent's
  "cgroup.subtree_control" enables it and disabled iff no child's
  "cgroup.subtree_control" has it enabled.

* If a cgroup has tasks, no controller can be enabled via
  "cgroup.subtree_control".  Likewise, if "cgroup.subtree_control" has
  some controllers enabled, tasks can't be migrated into the cgroup.

* All controllers which aren't bound on other hierarchies are
  automatically associated with the root cgroup of the default
  hierarchy.  All the controllers which are bound to the default
  hierarchy are listed in the read-only file "cgroup.controllers" in
  the root directory.

* "cgroup.controllers" in all non-root cgroups is read-only file whose
  content is equal to that of "cgroup.subtree_control" of the parent.
  This indicates which controllers can be used in the cgroup's
  "cgroup.subtree_control".

This is still experimental and there are some holes, one of which is
that ->can_attach() failure during cgroup_update_dfl_csses() may leave
the cgroups in an undefined state.  The issues will be addressed by
future patches.

v2: Non-root cgroups now also have "cgroup.controllers".
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

Unified hierarchy implementation would require re-migrating tasks onto
the same cgroup on the default hierarchy to reflect updated effective
csses.  Update cgroup_migrate_prepare_dst() so that it accepts NULL as
the destination cgrp.  When NULL is specified, the destination is
considered to be the cgroup on the default hierarchy associated with
each css_set.

After this change, the identity check in cgroup_migrate_add_src()
isn't sufficient for noop detection as the associated csses may change
without any cgroup association changing.  The only way to tell whether
a migration is noop or not is testing whether the source and
destination csets are identical.  The noop check in
cgroup_migrate_add_src() is removed and cset identity test is added to
cgroup_migreate_prepare_dst().  If it's detected that source and
destination csets are identical, the cset is removed removed from
@preloaded_csets and all the migration nodes are cleared which makes
cgroup_migrate() ignore the cset.

Also, make the function append the destination css_sets to
@preloaded_list so that destination css_sets always come after source
css_sets.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

Because the default root couldn't have any non-root csses attached to
it, rebinding away from it was always allowed; however, the default
hierarchy will soon host the unified hierarchy and have non-root csses
so the rebind restrictions need to be updated accordingly.

Instead of special casing rebinding from the default hierarchy and
then checking whether the source hierarchy has children cgroups, which
implies non-root csses for !dfl hierarchies, simply check whether the
source hierarchy has non-root csses for the subsystem using
css_next_child().
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

To implement the unified hierarchy behavior, we'll need to be able to
determine the associated cgroup on the default hierarchy from css_set.
Let's add css_set->dfl_cgrp so that it can be accessed conveniently
and efficiently.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

Now that effective css handling has been added and iterators updated
accordingly, it's safe to allow cgroup creation in the default
hierarchy.  Unblock cgroup creation in the default hierarchy.

As the default hierarchy will implement explicit enabling and
disabling of controllers on each cgroup, suppress automatic css
enabling on cgroup creation.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

After a css finishes offlining, offline_css() mistakenly performs
RCU_INIT_POINTER(css->cgroup->subsys[ss->id], css) which just sets the
cgroup->subsys[] pointer to the current value.  The intention was to
clear it after offline is complete, not reassign the same value.

Update it to assign NULL instead of the current value.  This makes
cgroup_css() to return NULL once offline is complete.  All the
existing users of the function either can handle NULL return already
or guarantee that the css doesn't get offlined.

While this is a bugfix, as css lifetime is currently tied to the
cgroup it belongs to, this bug doesn't cause any actual problems.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

Currently, css_task_iter iterates tasks associated with a css by
visiting each css_set associated with the owning cgroup and walking
tasks of each of them.  This works fine for !unified hierarchies as
each cgroup has its own css for each associated subsystem on the
hierarchy; however, on the planned unified hierarchy, a cgroup may not
have csses associated and its tasks would be considered associated
with the matching css of the nearest ancestor which has the subsystem
enabled.

This means that on the default unified hierarchy, just walking all
tasks associated with a cgroup isn't enough to walk all tasks which
are associated with the specified css.  If any of its children doesn't
have the matching css enabled, task iteration should also include all
tasks from the subtree.  We already added cgroup->e_csets[] to list
all css_sets effectively associated with a given css and walk css_sets
on that list instead to achieve such iteration.

This patch updates css_task_iter iteration such that it walks css_sets
on cgroup->e_csets[] instead of cgroup->cset_links if iteration is
requested on an non-dummy css.  Thanks to the previous iteration
update, this change can be achieved with the addition of
css_task_iter->ss and minimal updates to css_advance_task_iter() and
css_task_iter_start().
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

This patch reorganizes css_task_iter so that adding effective css
support is easier.

* s/->cset_link/->cset_pos/ and s/->task/->task_pos/ for consistency

* ->origin_css is used to determine whether the iteration reached the
  last css_set.  Replace it with explicit ->cset_head so that
  css_advance_task_iter() doesn't have to know the termination
  condition directly.

* css_task_iter_next() currently assumes that it's walking list of
  cgrp_cset_link and reaches into the current cset through the current
  link to determine the termination conditions for task walking.  As
  this won't always be true for effective css walking, add
  ->tasks_head and ->mg_tasks_head and use them to control task
  walking so that css_task_iter_next() doesn't have to know how
  css_sets are being walked.

This patch doesn't make any behavior changes.  The iteration logic
stays unchanged after the patch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

css_next_child() walks the children of the specified css.  It does
this by finding the next cgroup and then returning the requested css.
On the default unified hierarchy, a cgroup may not have a css
associated with it even if the hierarchy has the subsystem enabled.
This patch updates css_next_child() so that it skips children without
the requested css associated.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

On the default unified hierarchy, a cgroup may be associated with
csses of its ancestors, which means that a css of a given cgroup may
be associated with css_sets of descendant cgroups.  This means that we
can't walk all tasks associated with a css by iterating the css_sets
associated with the cgroup as there are css_sets which are pointing to
the css but linked on the descendants.

This patch adds per-subsystem list heads cgroup->e_csets[].  Any
css_set which is pointing to a css is linked to
css->cgroup->e_csets[$SUBSYS_ID] through
css_set->e_cset_node[$SUBSYS_ID].  The lists are protected by
css_set_rwsem and will allow us to walk all css_sets associated with a
given css so that we can find out all associated tasks.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

In the planned default unified hierarchy, controllers may get
dynamically attached to and detached from a cgroup and a cgroup may
not have csses for all the controllers associated with the hierarchy.

When a cgroup doesn't have its own css for a given controller, the css
of the nearest ancestor with the controller enabled will be used,
which is called the effective css.  This patch introduces
cgroup_e_css() and for_each_e_css() to access the effective csses and
convert compare_css_sets(), find_existing_css_set() and
cgroup_migrate() to use the effective csses so that they can handle
cgroups with partial csses correctly.

This means that for two css_sets to be considered identical, they
should have both matching csses and cgroups.  compare_css_sets()
already compares both, not for correctness but for optimization.  As
this now becomes a matter of correctness, update the comments
accordingly.

For all !default hierarchies, cgroup_e_css() always equals
cgroup_css(), so this patch doesn't change behavior.

While at it, fix incorrect locking comment for for_each_css().
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

94419627 ("cgroup: move ->subsys_mask from cgroupfs_root to
cgroup") moved ->subsys_mask from cgroup_root to cgroup to prepare for
the unified hierarhcy; however, it turns out that carrying the
subsys_mask of the children in the parent, instead of itself, is a lot
more natural.  This patch restores cgroup_root->subsys_mask and morphs
cgroup->subsys_mask into cgroup->child_subsys_mask.

* Uses of root->cgrp.subsys_mask are restored to root->subsys_mask.

* Remove automatic setting and clearing of cgrp->subsys_mask and
  instead just inherit ->child_subsys_mask from the parent during
  cgroup creation.  Note that this doesn't affect any current
  behaviors.

* Undo __kill_css() separation.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

cgroup_apply_cftypes() skip creating or removing files if the
subsystem is attached to the default hierarchy, which led to missing
files in the root of the default hierarchy.

Skipping made sense when the default hierarchy was dummy; however, now
that the default hierarchy is full functional and planned to be used
as the unified hierarchy, it shouldn't be skipped over.
Reported-by: NLi Zefan <lizefan@huawei.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

Pull slave-dmaengine fixes from Vinod Koul:
 "Back from long weekend here in India and now the time to send fixes
  for slave dmaengine.
   - Dan's fix of sirf xlate code
   - Jean's fix for timberland
   - edma fixes by Sekhar for SG handling and Yuan for changing init
     call"

* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
  dma: fix eDMA driver as a subsys_initcall
  dmaengine: sirf: off by one in of_dma_sirfsoc_xlate()
  platform: Fix timberdale dependencies
  dma: edma: fix incorrect SG list handling

Pull iommu fixes from Joerg Roedel:
 "Fixes for regressions:

   - fix wrong IOMMU enumeration causing some SCSI device drivers
     initialization failures
   - ARM-SMMU fixes for a panic condition and a wrong return value"

* tag 'iommu-fixes-v3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/arm-smmu: fix panic in arm_smmu_alloc_init_pte
  iommu/arm-smmu: Return 0 on unmap failure
  iommu/vt-d: fix bug in matching PCI devices with DRHD/RMRR descriptors
  iommu/vt-d: Fix get_domain_for_dev() handling of upstream PCIe bridges
  iommu/vt-d: fix memory leakage caused by commit ea8ea460

Pull perf tooling fixes from Ingo Molnar:
 "Three small tooling fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf tools: Improve error reporting
  perf tools: Adjust symbols in VDSO
  perf kvm: Fix 'Min time' counting in report command

Merge tag 'perf-urgent-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf into perf/urgent

Pull perf/urgent fixes from Jiri Olsa:

User visible changes:

  * Adjust symbols in VDSO to properly resolve its function names (Vladimir Nikulichev)

  * Improve error reporting for record session failure (Adrien BAK)

  * Fix 'Min time' counting in report command (Alexander Yarygin)
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

In the current version, when using perf record, if something goes
wrong in tools/perf/builtin-record.c:375
  session = perf_session__new(file, false, NULL);

The error message:
"Not enough memory for reading per file header"

is issued. This error message seems to be outdated and is not very
helpful. This patch proposes to replace this error message by
"Perf session creation failed"

I believe this issue has been brought to lkml:
https://lkml.org/lkml/2014/2/24/458
although this patch only tackles a (small) part of the issue.

Additionnaly, this patch improves error reporting in
tools/perf/util/data.c open_file_write.

Currently, if the call to open fails, the user is unaware of it.
This patch logs the error, before returning the error code to
the caller.
Reported-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NAdrien BAK <adrien.bak@metascale.org>
Link: http://lkml.kernel.org/r/1397786443.3093.4.camel@beast
[ Reorganize the changelog into paragraphs ]
[ Added empty line after fd declaration in open_file_write ]
Signed-off-by: NJiri Olsa <jolsa@redhat.com>

pert-report doesn't resolve function names in VDSO:

$ perf report --stdio -g flat,0.0,15,callee --sort pid
...
            8.76%
               0x7fff6b1fe861
               __gettimeofday
               ACE_OS::gettimeofday()
...

In this case symbol values should be adjusted the same way as for executables,
relocatable objects and prelinked libraries.

After fix:

$ perf report --stdio -g flat,0.0,15,callee --sort pid
...
            8.76%
               __vdso_gettimeofday
               __gettimeofday
               ACE_OS::gettimeofday()
Signed-off-by: NVladimir Nikulichev <nvs@tbricks.com>
Tested-by: NNamhyung Kim <namhyung@kernel.org>
Reviewed-by: NAdrian Hunter <adrian.hunter@intel.com>
Link: http://lkml.kernel.org/r/969812.163009436-sendEmail@nvsSigned-off-by: NJiri Olsa <jolsa@redhat.com>

Every event in the perf-kvm has a 'stats' structure, which contains
max/min/average/etc times of handling this event.
The problem is that the 'perf-kvm stat report' command always shows
that 'min time' is 0us for every event. Example:

 # perf kvm stat report

 Analyze events for all VCPUs:

    VM-EXIT    Samples  Samples%     Time%   Min Time   Max Time Avg time
  [..]
  0xB2 MSCH         12     0.07%     0.00%        0us        8us 7.31us ( +-   2.11% )
  0xB2 CHSC         12     0.07%     0.00%        0us       18us 9.39us ( +-   9.49% )
  0xB2 STPX          8     0.05%     0.00%        0us        2us 1.88us ( +-   7.18% )
  0xB2 STSI          7     0.04%     0.00%        0us       44us 16.49us ( +-  38.20% )
  [..]

This happens because the 'stats' structure is not initialized and
stats->min equals to 0. Lets initialize the structure for every
event after its allocation using init_stats() function. This initializes
stats->min to -1 and makes 'Min time' statistics counting work:

 # perf kvm stat report

 Analyze events for all VCPUs:

    VM-EXIT    Samples  Samples%     Time%   Min Time   Max Time Avg time
  [..]
  0xB2 MSCH         12     0.07%     0.00%        6us        8us 7.31us ( +-   2.11% )
  0xB2 CHSC         12     0.07%     0.00%        7us       18us 9.39us ( +-   9.49% )
  0xB2 STPX          8     0.05%     0.00%        1us        2us 1.88us ( +-   7.18% )
  0xB2 STSI          7     0.04%     0.00%        1us       44us 16.49us ( +-  38.20% )
  [..]
Signed-off-by: NAlexander Yarygin <yarygin@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/1397053319-2130-3-git-send-email-borntraeger@de.ibm.com
[ Fixing the perf examples changelog output ]
Signed-off-by: NJiri Olsa <jolsa@redhat.com>

A va_list needs to be copied in case it needs to be used twice.

Thanks to Hugh for debugging this issue, leading to various panics.

Tested:

  lpq84:~# echo "|/foobar12345 %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h" >/proc/sys/kernel/core_pattern

'produce_core' is simply : main() { *(int *)0 = 1;}

  lpq84:~# ./produce_core
  Segmentation fault (core dumped)
  lpq84:~# dmesg | tail -1
  [  614.352947] Core dump to |/foobar12345 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 (null) pipe failed

Notice the last argument was replaced by a NULL (we were lucky enough to
not crash, but do not try this on your production machine !)

After fix :

  lpq83:~# echo "|/foobar12345 %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h" >/proc/sys/kernel/core_pattern
  lpq83:~# ./produce_core
  Segmentation fault
  lpq83:~# dmesg | tail -1
  [  740.800441] Core dump to |/foobar12345 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 pipe failed

Fixes: 5fe9d8ca ("coredump: cn_vprintf() has no reason to call vsnprintf() twice")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Diagnosed-by: NHugh Dickins <hughd@google.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull x86 fix from Ingo Molnar:
 "This fixes the preemption-count imbalance crash reported by Owen
  Kibel"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Fix CMCI preemption bugs

Pull scheduler fixes from Ingo Molnar:
 "Two fixes:

   - a SCHED_DEADLINE task selection fix
   - a sched/numa related lockdep splat fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Check for stop task appearance when balancing happens
  sched/numa: Fix task_numa_free() lockdep splat

Pull perf fixes from Ingo Molnar:
 "Two kernel side fixes:

   - an Intel uncore PMU driver potential crash fix
   - a kprobes/perf-call-graph interaction fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU
  kprobes/x86: Fix page-fault handling logic

Pull drm fixes from Dave Airlie:
 "Unfortunately this contains no easter eggs, its a bit larger than I'd
  like, but I included a patch that just moves code from one file to
  another and I'd like to avoid merge conflicts with that later, so it
  makes it seem worse than it is,

  Otherwise:
   - radeon: fixes to use new microcode to stabilise some cards, use
     some common displayport code, some runtime pm fixes, pll regression
     fixes
   - i915: fix for some context oopses, a warn in a used path, backlight
     fixes
   - nouveau: regression fix
   - omap: a bunch of fixes"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (51 commits)
  drm: bochs: drop unused struct fields
  drm: bochs: add power management support
  drm: cirrus: add power management support
  drm: Split out drm_probe_helper.c from drm_crtc_helper.c
  drm/plane-helper: Don't fake-implement primary plane disabling
  drm/ast: fix value check in cbr_scan2
  drm/nouveau/bios: fix a bit shift error introduced by 457e77b2
  drm/radeon/ci: make sure mc ucode is loaded before checking the size
  drm/radeon/si: make sure mc ucode is loaded before checking the size
  drm/radeon: improve PLL params if we don't match exactly v2
  drm/radeon: memory leak on bo reservation failure. v2
  drm/radeon: fix VCE fence command
  drm/radeon: re-enable mclk dpm on R7 260X asics
  drm/radeon: add support for newer mc ucode on CI (v2)
  drm/radeon: add support for newer mc ucode on SI (v2)
  drm/radeon: apply more strict limits for PLL params v2
  drm/radeon: update CI DPM powertune settings
  drm/radeon: fix runpm handling on APUs (v4)
  drm/radeon: disable mclk dpm on R7 260X
  drm/tegra: Remove gratuitous pad field
  ...

Some i2c fixes over DisplayPort.

* 'drm-next-3.15-wip' of git://people.freedesktop.org/~deathsimple/linux:
  drm/radeon: Improve vramlimit module param documentation
  drm/radeon: fix audio pin counts for DCE6+ (v2)
  drm/radeon/dp: switch to the common i2c over aux code
  drm/dp/i2c: Update comments about common i2c over dp assumptions (v3)
  drm/dp/i2c: send bare addresses to properly reset i2c connections (v4)
  drm/radeon/dp: handle zero sized i2c over aux transactions (v2)
  drm/i915: support address only i2c-over-aux transactions
  drm/tegra: dp: Support address-only I2C-over-AUX transactions

Pull more networking fixes from David Miller:

 1) Fix mlx4_en_netpoll implementation, it needs to schedule a NAPI
    context, not synchronize it.  From Chris Mason.

 2) Ipv4 flow input interface should never be zero, it should be
    LOOPBACK_IFINDEX instead.  From Cong Wang and Julian Anastasov.

 3) Properly configure MAC to PHY connection in mvneta devices, from
    Thomas Petazzoni.

 4) sys_recv should use SYSCALL_DEFINE.  From Jan Glauber.

 5) Tunnel driver ioctls do not use the correct namespace, fix from
    Nicolas Dichtel.

 6) Fix memory leak on seccomp filter attach, from Kees Cook.

 7) Fix lockdep warning for nested vlans, from Ding Tianhong.

 8) Crashes can happen in SCTP due to how the auth_enable value is
    managed, fix from Vlad Yasevich.

 9) Wireless fixes from John W Linville and co.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (45 commits)
  net: sctp: cache auth_enable per endpoint
  tg3: update rx_jumbo_pending ring param only when jumbo frames are enabled
  vlan: Fix lockdep warning when vlan dev handle notification
  seccomp: fix memory leak on filter attach
  isdn: icn: buffer overflow in icn_command()
  ip6_tunnel: use the right netns in ioctl handler
  sit: use the right netns in ioctl handler
  ip_tunnel: use the right netns in ioctl handler
  net: use SYSCALL_DEFINEx for sys_recv
  net: mdio-gpio: Add support for separate MDI and MDO gpio pins
  net: mdio-gpio: Add support for active low gpio pins
  net: mdio-gpio: Use devm_ functions where possible
  ipv4, route: pass 0 instead of LOOPBACK_IFINDEX to fib_validate_source()
  ipv4, fib: pass LOOPBACK_IFINDEX instead of 0 to flowi4_iif
  mlx4_en: don't use napi_synchronize inside mlx4_en_netpoll
  net: mvneta: properly configure the MAC <-> PHY connection in all situations
  net: phy: add minimal support for QSGMII PHY
  sfc:On MCDI timeout, issue an FLR (and mark MCDI to fail-fast)
  mwifiex: fix hung task on command timeout
  mwifiex: process event before command response
  ...

Pull cifs fixes from Steve French:
 "A set of 5 small cifs fixes"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  cif: fix dead code
  cifs: fix error handling cifs_user_readv
  fs: cifs: remove unused variable.
  Return correct error on query of xattr on file with empty xattrs
  cifs: Wait for writebacks to complete before attempting write.