lglock: remove unused DEFINE_LGLOCK_LOCKDEP()

struct lglocks use their own lock_key/lock_dep_map which are defined in
struct lglock.  DEFINE_LGLOCK_LOCKDEP() is unused, so remove it and save a
small piece of memory.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lglock: make the per_cpu locks static

The per_cpu locks are not used outside the file which contains the
DEFINE_LGLOCK(), so we can make these symbols static.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lglock: add DEFINE_STATIC_LGLOCK()

When the lglock doesn't need to be exported we can use
DEFINE_STATIC_LGLOCK().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lglock: no need to keep brlock macros anymore

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lglock: Update lockdep annotations to report recursive local locks

Oleg Nesterov recently noticed that the lockdep annotations in lglock.c
are not sufficient to detect some obvious deadlocks, such as
lg_local_lock(LOCK) + lg_local_lock(LOCK) or spin_lock(X) +
lg_local_lock(Y) vs lg_local_lock(Y) + spin_lock(X).

Both issues are easily fixed by indicating to lockdep that lglock's local
locks are not recursive.  We shouldn't use the rwlock acquire/release
functions here, as lglock doesn't share the same semantics.  Instead we
can base our lockdep annotations on the lock_acquire_shared (for local
lglock) and lock_acquire_exclusive (for global lglock) helpers.

I am not proposing new lglock specific helpers as I don't see the point of
the existing second level of helpers :)

Noticed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130708212352.1769031C15E@corp2gmr1-1.hot.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
locking: Move the lglocks code to kernel/locking/

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-amd6pg1mif6tikbyktfvby3y@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
brlocks/lglocks: API cleanups

lglocks and brlocks are currently generated with some complicated macros
in lglock.h.  But there's no reason to not just use common utility
functions and put all the data into a common data structure.

In preparation, this patch changes the API to look more like normal
function calls with pointers, not magic macros.

The patch is rather large because I move over all users in one go to keep
it bisectable.  This impacts the VFS somewhat in terms of lines changed.
But no actual behaviour change.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
brlocks/lglocks: Linux 3.4.y compatibility fix ups

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lockdep: fix oops in processing workqueue

Under memory load, on x86_64, with lockdep enabled, the workqueue's
process_one_work() has been seen to oops in __lock_acquire(), barfing
on a 0xffffffff00000000 pointer in the lockdep_map's class_cache[].

Because it's permissible to free a work_struct from its callout function,
the map used is an onstack copy of the map given in the work_struct: and
that copy is made without any locking.

Surprisingly, gcc (4.5.1 in Hugh's case) uses "rep movsl" rather than
"rep movsq" for that structure copy: which might race with a workqueue
user's wait_on_work() doing lock_map_acquire() on the source of the
copy, putting a pointer into the class_cache[], but only in time for
the top half of that pointer to be copied to the destination map.

Boom when process_one_work() subsequently does lock_map_acquire()
on its onstack copy of the lockdep_map.

Fix this, and a similar instance in call_timer_fn(), with a
lockdep_copy_map() function which additionally NULLs the class_cache[].

Note: this oops was actually seen on 3.4-next, where flush_work() newly
does the racing lock_map_acquire(); but Tejun points out that 3.4 and
earlier are already vulnerable to the same through wait_on_work().

* Patch orginally from Peter.  Hugh modified it a bit and wrote the
  description.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Reported-by: Hugh Dickins <hughd@google.com>
LKML-Reference: <alpine.LSU.2.00.1205070951170.1544@eggly.anvils>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lockdep: Introduce lock_acquire_exclusive()/shared() helper macros

In lockdep.h, the spinlock/mutex/rwsem/rwlock/lock_map acquire macros have
different definitions based on the value of CONFIG_PROVE_LOCKING.  We have
separate ifdefs for each of these definitions, which seems redundant.

Introduce lock_acquire_{exclusive,shared,shared_recursive} helpers which
will have different definitions based on CONFIG_PROVE_LOCKING.  Then all
other helper macros can be defined based on the above ones, which reduces
the amount of ifdefined code.

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20130708212350.6DD1931C15E@corp2gmr1-1.hot.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>