As Dan Streetman points out, the entire point of locking for is to
stop sysfs accesses, so they're elided entirely in the !SYSFS case.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This mirrors the change introduced by 7d0ae808 of same title
in Linus' tree; it's not obvious as a merge resolution since we moved
the function.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Add a "param_lock" mutex to each module, and update params.c to use
the correct built-in or module mutex while locking kernel params.
Remove the kparam_block_sysfs_r/w() macros, replace them with direct
calls to kernel_param_[un]lock(module).

The kernel param code currently uses a single mutex to protect
modification of any and all kernel params.  While this generally works,
there is one specific problem with it; a module callback function
cannot safely load another module, i.e. with request_module() or even
with indirect calls such as crypto_has_alg().  If the module to be
loaded has any of its params configured (e.g. with a /etc/modprobe.d/*
config file), then the attempt will result in a deadlock between the
first module param callback waiting for modprobe, and modprobe trying to
lock the single kernel param mutex to set the new module's param.

This fixes that by using per-module mutexes, so that each individual module
is protected against concurrent changes in its own kernel params, but is
not blocked by changes to other module params.  All built-in modules
continue to use the built-in mutex, since they will always be loaded at
runtime and references (e.g. request_module(), crypto_has_alg()) to them
will never cause load-time param changing.

This also simplifies the interface used by modules to block sysfs access
to their params; while there are currently functions to block and unblock
sysfs param access which are split up by read and write and expect a single
kernel param to be passed, their actual operation is identical and applies
to all params, not just the one passed to them; they simply lock and unlock
the global param mutex.  They are replaced with direct calls to
kernel_param_[un]lock(THIS_MODULE), which locks THIS_MODULE's param_lock, or
if the module is built-in, it locks the built-in mutex.
Suggested-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Change the struct kernel_param.perm field to a const, as it should never
be changed.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cut from larger patch)

It shouldn't fail due to OOM (it's boot time), and already warns if we
get two identical names.  But you never know what the future holds, and
WARN_ON_ONCE() keeps gcc happy with minimal code.
Reported-by: NLouis Langholtz <lou_langholtz@me.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Andreas turned this option on, only to find out Debian (and Ubuntu!)
don't enable support in their kmod builds.

Shorten the text, and suggest N at the bottom (at least for now).
Reported-by: NAndreas Mohr <andim2@users.sf.net>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

There's no need to require an ifdef over the declaration
of sig_enforce as IS_ENABLED() can be used. While at it,
there's no harm in exposing this kernel parameter outside of
CONFIG_MODULE_SIG as it'd be a no-op on non module sig
kernels.

Now, technically we should in theory be able to remove
the #ifdef'ery over the declaration of the module parameter
as we are also trusting the bool_enable_only code for
CONFIG_MODULE_SIG kernels but for now remain paranoid
and keep it.

With time if no one can put a bullet through bool_enable_only
and if there are no technical requirements over not exposing
CONFIG_MODULE_SIG_FORCE with the measures in place by
bool_enable_only we could remove this last ifdef.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: cocci@systeme.lip6.fr
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

We can avoid an ifdef over wq_power_efficient's declaration
by just using IS_ENABLED().

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: cocci@systeme.lip6.fr
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This will grant access to this helper to code built as modules.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Kyle McMartin <kyle@kernel.org>
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This takes out the bool_enable_only implementation from
the module loading code and generalizes it so that others
can make use of it.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: cocci@systeme.lip6.fr
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

We're directly checking and modifying sig_enforce when needed instead
of using the generic helpers. This prevents us from generalizing this
helper so that others can use it. Use indirect helpers to allow us
to generalize this code a bit and to make it a bit more clear what
this is doing.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: cocci@systeme.lip6.fr
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Most code already uses consts for the struct kernel_param_ops,
sweep the kernel for the last offending stragglers. Other than
include/linux/moduleparam.h and kernel/params.c all other changes
were generated with the following Coccinelle SmPL patch. Merge
conflicts between trees can be handled with Coccinelle.

In the future git could get Coccinelle merge support to deal with
patch --> fail --> grammar --> Coccinelle --> new patch conflicts
automatically for us on patches where the grammar is available and
the patch is of high confidence. Consider this a feature request.

Test compiled on x86_64 against:

	* allnoconfig
	* allmodconfig
	* allyesconfig

@ const_found @
identifier ops;
@@

const struct kernel_param_ops ops = {
};

@ const_not_found depends on !const_found @
identifier ops;
@@

-struct kernel_param_ops ops = {
+const struct kernel_param_ops ops = {
};

Generated-by: Coccinelle SmPL
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Junio C Hamano <gitster@pobox.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: cocci@systeme.lip6.fr
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

There were some inconsistency in restriction to VERIFY_OCTAL_PERMISSIONS().
Previously the test was "User perms >= group perms >= other perms". The
permission field of User, Group or Other consists of three bits. LSB is
EXECUTE permission, MSB is READ permission and the middle bit is WRITE
permission. But logically WRITE is "more privileged" than READ.

Say for example, permission value is "0430". Here User has only READ
permission whereas Group has both WRITE and EXECUTE permission.

So, the checks could be tightened and the tests are separated to
USER_READABLE >= GROUP_READABLE >= OTHER_READABLE,
USER_WRITABLE >= GROUP_WRITABLE and OTHER_WRITABLE is not permitted.
Signed-off-by: NGobinda Charan Maji <gobinda.cemk07@gmail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

__module_address() does an initial bound check before doing the
{list/tree} iteration to find the actual module. The bound variables
are nowhere near the mod_tree cacheline, in fact they're nowhere near
one another.

module_addr_min lives in .data while module_addr_max lives in .bss
(smarty pants GCC thinks the explicit 0 assignment is a mistake).

Rectify this by moving the two variables into a structure together
with the latch_tree_root to guarantee they all share the same
cacheline and avoid hitting two extra cachelines for the lookup.

While reworking the bounds code, move the bound update from allocation
to insertion time, this avoids updating the bounds for a few error
paths.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Use the generic __module_address() addr to struct module lookup
instead of open coding it once more.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Andrew worried about the overhead on small systems; only use the fancy
code when either perf or tracing is enabled.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Requested-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Currently __module_address() is using a linear search through all
modules in order to find the module corresponding to the provided
address. With a lot of modules this can take a lot of time.

One of the users of this is kernel_text_address() which is employed
in many stack unwinders; which in turn are used by perf-callchain and
ftrace (possibly from NMI context).

So by optimizing __module_address() we optimize many stack unwinders
which are used by both perf and tracing in performance sensitive code.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Implement a latched RB-tree in order to get unconditional RCU/lockless
lookups.

Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Because with latches there is a strict data dependency on the seq load
we can avoid the rmb in favour of a read_barrier_depends.
Suggested-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

I want to use lockless_dereference() from seqlock.h, which would mean
including rcupdate.h from it, however rcupdate.h already includes
seqlock.h.

Avoid this by moving lockless_dereference() into compiler.h. This is
somewhat tricky since it uses smp_read_barrier_depends() which isn't
available there, but its a CPP macro so we can get away with it.

The alternative would be moving it into asm/barrier.h, but that would
be updating each arch (I can do if people feel that is more
appropriate).

Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Improve the documentation of the latch technique as used in the
current timekeeping code, such that it can be readily employed
elsewhere.

Borrow from the comments in timekeeping and replace those with a
reference to this more generic comment.

Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: NMichel Lespinasse <walken@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Change the insert and erase code such that lockless searches are
non-fatal.

In and of itself an rbtree cannot be correctly searched while
in-modification, we can however provide weaker guarantees that will
allow the rbtree to be used in conjunction with other techniques, such
as latches; see 9b0fd802 ("seqcount: Add raw_write_seqcount_latch()").

For this to work we need the following guarantees from the rbtree
code:

 1) a lockless reader must not see partial stores, this would allow it
    to observe nodes that are invalid memory.

 2) there must not be (temporary) loops in the tree structure in the
    modifier's program order, this would cause a lookup which
    interrupts the modifier to get stuck indefinitely.

For 1) we must use WRITE_ONCE() for all updates to the tree structure;
in particular this patch only does rb_{left,right} as those are the
only element required for simple searches.

It generates slightly worse code, probably because volatile. But in
pointer chasing heavy code a few instructions more should not matter.

For 2) I have carefully audited the code and drawn every intermediate
link state and not found a loop.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Reviewed-by: NMichel Lespinasse <walken@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Currently the RCU usage in module is an inconsistent mess of RCU and
RCU-sched, this is broken for CONFIG_PREEMPT where synchronize_rcu()
does not imply synchronize_sched().

Most usage sites use preempt_{dis,en}able() which is RCU-sched, but
(most of) the modification sites use synchronize_rcu(). With the
exception of the module bug list, which actually uses RCU.

Convert everything over to RCU-sched.

Furthermore add lockdep asserts to all sites, because it's not at all
clear to me the required locking is observed, esp. on exported
functions.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: N"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

As per the module core lockdep annotations in the coming patch:

[   18.034047] ---[ end trace 9294429076a9c673 ]---
[   18.047760] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
[   18.059228]  ffffffff817d8676 ffff880036683c38 ffffffff8157e98b 0000000000000001
[   18.067541]  0000000000000000 ffff880036683c78 ffffffff8105fbc7 ffff880036683c68
[   18.075851]  ffffffffa0046b08 0000000000000000 ffffffffa0046d00 ffffffffa0046cc8
[   18.084173] Call Trace:
[   18.086906]  [<ffffffff8157e98b>] dump_stack+0x4f/0x7b
[   18.092649]  [<ffffffff8105fbc7>] warn_slowpath_common+0x97/0xe0
[   18.099361]  [<ffffffff8105fc2a>] warn_slowpath_null+0x1a/0x20
[   18.105880]  [<ffffffff810ee502>] __module_address+0x1d2/0x1e0
[   18.112400]  [<ffffffff81161153>] jump_label_module_notify+0x143/0x1e0
[   18.119710]  [<ffffffff810814bf>] notifier_call_chain+0x4f/0x70
[   18.126326]  [<ffffffff8108160e>] __blocking_notifier_call_chain+0x5e/0x90
[   18.134009]  [<ffffffff81081656>] blocking_notifier_call_chain+0x16/0x20
[   18.141490]  [<ffffffff810f0f00>] load_module+0x1b50/0x2660
[   18.147720]  [<ffffffff810f1ade>] SyS_init_module+0xce/0x100
[   18.154045]  [<ffffffff81587429>] system_call_fastpath+0x12/0x17
[   18.160748] ---[ end trace 9294429076a9c674 ]---

Jump labels is not doing it right; fix this.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jason Baron <jbaron@akamai.com>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Due to the new lockdep checks in the coming patch, we go:

[    9.759380] ------------[ cut here ]------------
[    9.759389] WARNING: CPU: 31 PID: 597 at ../kernel/module.c:216 each_symbol_section+0x121/0x130()
[    9.759391] Modules linked in:
[    9.759393] CPU: 31 PID: 597 Comm: modprobe Not tainted 4.0.0-rc1+ #65
[    9.759393] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
[    9.759396]  ffffffff817d8676 ffff880424567ca8 ffffffff8157e98b 0000000000000001
[    9.759398]  0000000000000000 ffff880424567ce8 ffffffff8105fbc7 ffff880424567cd8
[    9.759400]  0000000000000000 ffffffff810ec160 ffff880424567d40 0000000000000000
[    9.759400] Call Trace:
[    9.759407]  [<ffffffff8157e98b>] dump_stack+0x4f/0x7b
[    9.759410]  [<ffffffff8105fbc7>] warn_slowpath_common+0x97/0xe0
[    9.759412]  [<ffffffff810ec160>] ? section_objs+0x60/0x60
[    9.759414]  [<ffffffff8105fc2a>] warn_slowpath_null+0x1a/0x20
[    9.759415]  [<ffffffff810ed9c1>] each_symbol_section+0x121/0x130
[    9.759417]  [<ffffffff810eda01>] find_symbol+0x31/0x70
[    9.759420]  [<ffffffff810ef5bf>] load_module+0x20f/0x2660
[    9.759422]  [<ffffffff8104ef10>] ? __do_page_fault+0x190/0x4e0
[    9.759426]  [<ffffffff815880ec>] ? retint_restore_args+0x13/0x13
[    9.759427]  [<ffffffff815880ec>] ? retint_restore_args+0x13/0x13
[    9.759433]  [<ffffffff810ae73d>] ? trace_hardirqs_on_caller+0x11d/0x1e0
[    9.759437]  [<ffffffff812fcc0e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[    9.759439]  [<ffffffff815880ec>] ? retint_restore_args+0x13/0x13
[    9.759441]  [<ffffffff810f1ade>] SyS_init_module+0xce/0x100
[    9.759443]  [<ffffffff81587429>] system_call_fastpath+0x12/0x17
[    9.759445] ---[ end trace 9294429076a9c644 ]---

As per the comment this site should be fine, but lets wrap it in
preempt_disable() anyhow to placate lockdep.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Pull pin control fixes from Linus Walleij:
 "Here are some three pin control fixes for the v4.1 cycle, all
  driver-specific.  Business as usual and calm as it should be in this
  portion of the merge window.

   - IRQ trigger fix for the Intel Cherryview

   - GPIO-to-pin mapping fix for the Cygnus driver

   - GPIO-to-pin mapping fix for the Meson8b driver"

* tag 'pinctrl-v4.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: Fix gpio/pin mapping for Meson8b
  pinctrl: cygnus: fixed incorrect GPIO-pin mapping
  pinctrl: cherryview: Read triggering type from HW if not set when requested

Pull GPIO fixes from Linus Walleij:
 "Here are two GPIO fixes targeted for stable:

   - a leak in gpiochip_add path destined for stable

   - a kempld driver bug destined for stable"

* tag 'gpio-v4.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: gpio-kempld: Fix get_direction return value
  gpio: fix gpio leak in gpiochip_add error path

Pull SCSI fixes from James Bottomley:
 "This is a set of five fixes: Two MAINTAINER email updates (urgent
  because the non-avagotech emails will start bouncing) an lpfc big
  endian oops fix, a 256 byte sector hang fix (to eliminate 256 byte
  sectors) and a storvsc fix which could cause test unit ready failures
  on bringup"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  MAINTAINERS: Revise lpfc maintainers for Avago Technologies ownership of Emulex
  MAINTAINERS, be2iscsi: change email domain
  sd: Disable support for 256 byte/sector disks
  lpfc: Fix breakage on big endian kernels
  storvsc: Set the SRB flags correctly when no data transfer is needed

Pull timer fix from Thomas Gleixner:
 "One more fix from the timer departement:

    - Handle division of negative nanosecond values proper on 32bit.

      A recent cleanup wrecked the sign handling of the dividend and
      dropped the check for negative divisors"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ktime: Fix ktime_divns to do signed division

Pull irqchip fix from Thomas Gleixner:
 "A fix for a GIC-V3 irqchip regression which prevents some systems from
  booting"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gicv3-its: ITS table size should not be smaller than PSZ

Pull two Ceph fixes from Sage Weil:
 "These fix an issue with the RBD notifications when there are topology
  changes in the cluster"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  Revert "libceph: clear r_req_lru_item in __unregister_linger_request()"
  libceph: request a new osdmap if lingering request maps to no osd

Pull btrfs fixes from Chris Mason:
 "I fixed up a regression from 4.0 where conversion between different
  raid levels would sometimes bail out without converting.

  Filipe tracked down a race where it was possible to double allocate
  chunks on the drive.

  Mark has a fix for fiemap.  All three will get bundled off for stable
  as well"

* 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix regression in raid level conversion
  Btrfs: fix racy system chunk allocation when setting block group ro
  btrfs: clear 'ret' in btrfs_check_shared() loop

Pull drm fixes from Dave Airlie:
 "Radeon has two displayport fixes, one for a regression.

  i915 regression flicker fix needed so 4.0 can get fixed.

  A bunch of msm fixes and a bunch of exynos fixes, these two are
  probably a bit larger than I'd like, but most of them seems pretty
  good"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (29 commits)
  drm/radeon: fix error flag checking in native aux path
  drm/radeon: retry dcpd fetch
  drm/msm/mdp5: fix incorrect parameter for msm_framebuffer_iova()
  drm/exynos: dp: Lower level of EDID read success message
  drm/exynos: cleanup exynos_drm_plane
  drm/exynos: 'win' is always unsigned
  drm/exynos: mixer: don't dump registers under spinlock
  drm/exynos: Consolidate return statements in fimd_bind()
  drm/exynos: Constify exynos_drm_crtc_ops
  drm/exynos: Fix build breakage on !DRM_EXYNOS_FIMD
  drm/exynos: mixer: Constify platform_device_id
  drm/exynos: mixer: cleanup pixelformat handling
  drm/exynos: mixer: also allow NV21 for the video processor
  drm/exynos: mixer: remove buffer count handling in vp_video_buffer()
  drm/exynos: plane: honor buffer offset for dma_addr
  drm/exynos: fb: use drm_format_num_planes to get buffer count
  drm/i915: fix screen flickering
  drm/msm: fix locking inconsistencies in gpu->destroy()
  drm/msm/dsi: Simplify the code to get the number of read byte
  drm/msm: Attach assigned encoder to eDP and DSI connectors
  ...

Pull networking fixes from David Miller:

 1) Don't leak ipvs->sysctl_tbl, from Tommi Rentala.

 2) Fix neighbour table entry leak in rocker driver, from Ying Xue.

 3) Do not emit bonding notifications for unregistered interfaces, from
    Nicolas Dichtel.

 4) Set ipv6 flow label properly when in TIME_WAIT state, from Florent
    Fourcot.

 5) Fix regression in ipv6 multicast filter test, from Henning Rogge.

 6) do_replace() in various footables netfilter modules is missing a
    check for 0 counters in the datastructure provided by the user.  Fix
    from Dave Jones, and found with trinity.

 7) Fix RCU bug in packet scheduler classifier module unloads, from
    Daniel Borkmann.

 8) Avoid deadlock in tcp_get_info() by using u64_sync.  From Eric
    Dumzaet.

 9) Input packet processing can race with inetdev_destroy() teardown,
    fix potential OOPS in ip_error() by explicitly testing whether the
    inetdev is still attached.  From Eric W Biederman.

10) MLDv2 parser in bridge multicast code breaks too early while
    parsing.  Fix from Thadeu Lima de Souza Cascardo.

11) Asking for settings on non-zero PHYID doesn't work because we do not
    import the command structure from the user and use the PHYID
    provided there.  Fix from Arun Parameswaran.

12) Fix UDP checksums with IPV6 RAW sockets, from Vlad Yasevich.

13) Missing NF_TABLES depends for TPROXY etc can cause build failures,
    fix from Florian Westphal.

14) Fix netfilter conntrack to handle RFC5961 challenge ACKs properly,
    from Jesper Dangaard Brouer.

15) If netlink autobind retry fails, we have to reset the sockets portid
    back to zero.  From Herbert Xu.

16) VXLAN netns exit code unregisters using wrong device, from John W
    Linville.

17) Add some USB device IDs to ath3k and btusb bluetooth drivers, from
    Dmitry Tunin and Wen-chien Jesse Sung.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (44 commits)
  bridge: fix lockdep splat
  net: core: 'ethtool' issue with querying phy settings
  bridge: fix parsing of MLDv2 reports
  ARM: zynq: DT: Use the zynq binding with macb
  net: macb: Disable half duplex gigabit on Zynq
  net: macb: Document zynq gem dt binding
  ipv4: fill in table id when replacing a route
  cdc_ncm: Fix tx_bytes statistics
  ipv4: Avoid crashing in ip_error
  tcp: fix a potential deadlock in tcp_get_info()
  net: sched: fix call_rcu() race on classifier module unloads
  net: phy: Make sure phy_start() always re-enables the phy interrupts
  ipv6: fix ECMP route replacement
  ipv6: do not delete previously existing ECMP routes if add fails
  Revert "netfilter: bridge: query conntrack about skb dnat"
  netfilter: ensure number of counters is >0 in do_replace()
  netfilter: nfnetlink_{log,queue}: Register pernet in first place
  tcp: don't over-send F-RTO probes
  tcp: only undo on partial ACKs in CA_Loss
  net/ipv6/udp: Fix ipv6 multicast socket filter regression
  ...

Pull block fixes from Jens Axboe:
 "Three small fixes that have been picked up the last few weeks.
  Specifically:

   - Fix a memory corruption issue in NVMe with malignant user
     constructed request.  From Christoph.

   - Kill (now) unused blk_queue_bio(), dm was changed to not need this
     anymore.  From Mike Snitzer.

   - Always use blk_schedule_flush_plug() from the io_schedule() path
     when flushing a plug, fixing a !TASK_RUNNING warning with md.  From
     Shaohua"

* 'for-linus' of git://git.kernel.dk/linux-block:
  sched: always use blk_schedule_flush_plug in io_schedule_out
  nvme: fix kernel memory corruption with short INQUIRY buffers
  block: remove export for blk_queue_bio

Pull md bugfixes from Neil Brown:
 "I have a few more raid5 bugfixes pending, but I want them to get a bit
  more review first.  In the meantime:

   - one serious RAID0 data corruption - caused by recent bugfix that
     wasn't reviewed properly.

   - one raid5 fix in new code (a couple more of those to come).

   - one little fix to stop static analysis complaining about silly rcu
     annotation"

* tag 'md/4.1-rc4-fixes' of git://neil.brown.name/md:
  md/bitmap: remove rcu annotation from pointer arithmetic.
  md/raid0: fix restore to sector variable in raid0_make_request
  raid5: fix broken async operation chain

Pull input fixes from Dmitry Torokhov:
 "Updates for the input subsystem.

  The main change is that we tell joydev not to touch "absolute mice",
  such as VMware virtual mouse, as that produced bad result (cursor
  stuck in upper right corner) with games"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: smtpe-ts - wait 50mS until polling for pen-up
  Input: smtpe-ts - use msecs_to_jiffies() instead of HZ
  Input: joydev - don't classify the vmmouse as a joystick
  Input: vmmouse - do not reference non-existing version of X driver
  Input: alps - fix finger jumps on lifting 2 fingers on v7 touchpad
  Input: elantech - fix semi-mt protocol for v3 HW
  Input: sx8654 - fix memory allocation check

Pull another crypto fix from Herbert Xu:
 "Fix ICV corruption in s390/ghash when the same tfm is used by more
  than one thread"

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: s390/ghash - Fix incorrect ghash icv buffer handling.

Following lockdep splat was reported :

[   29.382286] ===============================
[   29.382315] [ INFO: suspicious RCU usage. ]
[   29.382344] 4.1.0-0.rc0.git11.1.fc23.x86_64 #1 Not tainted
[   29.382380] -------------------------------
[   29.382409] net/bridge/br_private.h:626 suspicious
rcu_dereference_check() usage!
[   29.382455]
               other info that might help us debug this:

[   29.382507]
               rcu_scheduler_active = 1, debug_locks = 0
[   29.382549] 2 locks held by swapper/0/0:
[   29.382576]  #0:  (((&p->forward_delay_timer))){+.-...}, at:
[<ffffffff81139f75>] call_timer_fn+0x5/0x4f0
[   29.382660]  #1:  (&(&br->lock)->rlock){+.-...}, at:
[<ffffffffa0450dc1>] br_forward_delay_timer_expired+0x31/0x140
[bridge]
[   29.382754]
               stack backtrace:
[   29.382787] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.1.0-0.rc0.git11.1.fc23.x86_64 #1
[   29.382838] Hardware name: LENOVO 422916G/LENOVO, BIOS A1KT53AUS 04/07/2015
[   29.382882]  0000000000000000 3ebfc20364115825 ffff880666603c48
ffffffff81892d4b
[   29.382943]  0000000000000000 ffffffff81e124e0 ffff880666603c78
ffffffff8110bcd7
[   29.383004]  ffff8800785c9d00 ffff88065485ac58 ffff880c62002800
ffff880c5fc88ac0
[   29.383065] Call Trace:
[   29.383084]  <IRQ>  [<ffffffff81892d4b>] dump_stack+0x4c/0x65
[   29.383130]  [<ffffffff8110bcd7>] lockdep_rcu_suspicious+0xe7/0x120
[   29.383178]  [<ffffffffa04520f9>] br_fill_ifinfo+0x4a9/0x6a0 [bridge]
[   29.383225]  [<ffffffffa045266b>] br_ifinfo_notify+0x11b/0x4b0 [bridge]
[   29.383271]  [<ffffffffa0450d90>] ? br_hold_timer_expired+0x70/0x70 [bridge]
[   29.383320]  [<ffffffffa0450de8>]
br_forward_delay_timer_expired+0x58/0x140 [bridge]
[   29.383371]  [<ffffffffa0450d90>] ? br_hold_timer_expired+0x70/0x70 [bridge]
[   29.383416]  [<ffffffff8113a033>] call_timer_fn+0xc3/0x4f0
[   29.383454]  [<ffffffff81139f75>] ? call_timer_fn+0x5/0x4f0
[   29.383493]  [<ffffffff8110a90f>] ? lock_release_holdtime.part.29+0xf/0x200
[   29.383541]  [<ffffffffa0450d90>] ? br_hold_timer_expired+0x70/0x70 [bridge]
[   29.383587]  [<ffffffff8113a6a4>] run_timer_softirq+0x244/0x490
[   29.383629]  [<ffffffff810b68cc>] __do_softirq+0xec/0x670
[   29.383666]  [<ffffffff810b70d5>] irq_exit+0x145/0x150
[   29.383703]  [<ffffffff8189f506>] smp_apic_timer_interrupt+0x46/0x60
[   29.383744]  [<ffffffff8189d523>] apic_timer_interrupt+0x73/0x80
[   29.383782]  <EOI>  [<ffffffff816f131f>] ? cpuidle_enter_state+0x5f/0x2f0
[   29.383832]  [<ffffffff816f131b>] ? cpuidle_enter_state+0x5b/0x2f0

Problem here is that br_forward_delay_timer_expired() is a timer
handler, calling br_ifinfo_notify() which assumes either rcu_read_lock()
or RTNL are held.

Simplest fix seems to add rcu read lock section.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NJosh Boyer <jwboyer@fedoraproject.org>
Reported-by: NDominick Grift <dac.override@gmail.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>