[tip:locking/core] locking/lockdep: Provide empty lockdep_map structure for !CONFIG_LOCKDEP

[tip-bot for Byungchul Park]

Commit-ID:  6f0397d7e100f3b3978d6ebb6b2dea29ee7c4a95
Gitweb:     https://git.kernel.org/tip/6f0397d7e100f3b3978d6ebb6b2dea29ee7c4a95
Author:     Byungchul Park <byungchul.park@xxxxxxx>
AuthorDate: Wed, 25 Oct 2017 17:55:58 +0900
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 25 Oct 2017 12:19:00 +0200

locking/lockdep: Provide empty lockdep_map structure for !CONFIG_LOCKDEP

After this patch the lockdep_map structure takes no space if lockdep is
disabled, reducing the number of #ifdefs in unrelated kernel code.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: amir73il@xxxxxxxxx
Cc: axboe@xxxxxxxxx
Cc: darrick.wong@xxxxxxxxxx
Cc: david@xxxxxxxxxxxxx
Cc: hch@xxxxxxxxxxxxx
Cc: idryomov@xxxxxxxxx
Cc: johan@xxxxxxxxxx
Cc: johannes.berg@xxxxxxxxx
Cc: kernel-team@xxxxxxx
Cc: linux-block@xxxxxxxxxxxxxxx
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-xfs@xxxxxxxxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: tj@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1508921765-15396-3-git-send-email-byungchul.park@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/lockdep.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index bfa8e0b..b6662d0 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -527,6 +527,11 @@ static inline void lockdep_on(void)
  */
 struct lock_class_key { };
 
+/*
+ * The lockdep_map takes no space if lockdep is disabled:
+ */
+struct lockdep_map { };
+
 #define lockdep_depth(tsk)	(0)
 
 #define lockdep_is_held_type(l, r)		(1)