rbtree: fix incorrect rbtree node insertion in fs/proc/proc_sysctl.c

The recently added code to use rbtrees in sysctl did not follow the proper
rbtree interface on insertion - it was calling rb_link_node() which
inserts a new node into the binary tree, but missed the call to
rb_insert_color() which properly balances the rbtree and establishes all
expected rbtree invariants.

I found out about this only because faulty commit also used
rb_init_node(), which I am removing within this patchset.  But I think
it's an easy mistake to make, and it makes me wonder if we should change
the rbtree API so that insertions would be done with a single rb_insert()
call (even if its implementation could still inline the rb_link_node()
part and call a private __rb_insert_color function to do the rebalancing).

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Santos <daniel.santos@pobox.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
rbtree: include linux/compiler.h for definition of __always_inline

rb_erase_augmented() is a static function annotated with
__always_inline.  This causes a compile failure when attempting to use
the rbtree implementation as a library (e.g.  kvm tool):

  rbtree_augmented.h:125:24: error: expected `=', `,', `;', `asm' or `__attribute__' before `void'

Include linux/compiler.h in rbtree_augmented.h so that the __always_inline
macro is resolved correctly.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
lib/rbtree.c: avoid the use of non-static __always_inline

lib/rbtree.c declared __rb_erase_color() as __always_inline void, and
then exported it with EXPORT_SYMBOL.

This was because __rb_erase_color() must be exported for augmented
rbtree users, but it must also be inlined into rb_erase() so that the
dummy callback can get optimized out of that call site.

(Actually with a modern compiler, none of the dummy callback functions
should even be generated as separate text functions).

The above usage is legal C, but it was unusual enough for some compilers
to warn about it.  This change makes things more explicit, with a static
__always_inline ____rb_erase_color function for use in rb_erase(), and a
separate non-inline __rb_erase_color function for use in
rb_erase_augmented call sites.

Signed-off-by: Michel Lespinasse <walken@google.com>
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
regmap: rbtree: Don't bother checking for noop updates

If we're updating a value in place it's more work to read the value and
compare the value with what we're about to set than it is to just write
the value into the cache; there are no further operations after writing
in the code even though there's an early return here.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
rtmutex: Fix initialization

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: Dan Trifan <jimsth@gmail.com>