[PATCH 13/17] locking/lockdep: Add nest lock type

[Yuyang Du]

Add a macro LOCK_TYPE_NEST for nest lock type and mark the nested lock in
check_deadlock_current(). Unlike the other LOCK_TYPE_* enums, this lock type
is used only in lockdep.

No functional change.

Signed-off-by: Yuyang Du <duyuyang@xxxxxxxxx>
---
 kernel/locking/lockdep.c           | 7 +++++--
 kernel/locking/lockdep_internals.h | 1 +
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c94c105..417b23d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2523,6 +2523,7 @@ static inline void inc_chains(void)
  *  0: on deadlock detected;
  *  1: on OK;
  *  2: LOCK_TYPE_RECURSIVE on recursive read
+ *  3: LOCK_TYPE_NEST on nest lock
  */
 static int
 check_deadlock_current(struct task_struct *curr, struct held_lock *next)
@@ -2552,7 +2553,7 @@ static inline void inc_chains(void)
 		 * nesting behaviour.
 		 */
 		if (nest)
-			return LOCK_TYPE_RECURSIVE;
+			return LOCK_TYPE_NEST;
 
 		print_deadlock_bug(curr, prev, next);
 		return 0;
@@ -3127,11 +3128,13 @@ static int validate_chain(struct task_struct *curr,
 
 		if (!ret)
 			return 0;
+
 		/*
 		 * Add dependency only if this lock is not the head
 		 * of the chain, and if it's not a secondary read-lock:
 		 */
-		if (!chain_head && ret != LOCK_TYPE_RECURSIVE) {
+		if (!chain_head && ret != LOCK_TYPE_RECURSIVE &&
+		    ret != LOCK_TYPE_NEST) {
 			if (!check_prevs_add(curr, hlock))
 				return 0;
 		}
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index c287bcb..b06c405 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -28,6 +28,7 @@ enum lock_usage_bit {
 
 #define LOCK_TYPE_BITS	16
 #define LOCK_TYPE_MASK	0xFFFF
+#define LOCK_TYPE_NEST	3
 
 /*
  * Usage-state bitmasks:
-- 
1.8.3.1