linux-kernel - [PATCH v3 25/30] locking/lockdep: Add nest lock type

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Date:   Fri, 28 Jun 2019 17:15:23 +0800
From:   Yuyang Du <duyuyang@...il.com>
To:     peterz@...radead.org, will.deacon@....com, mingo@...nel.org
Cc:     bvanassche@....org, ming.lei@...hat.com, frederic@...nel.org,
        tglx@...utronix.de, linux-kernel@...r.kernel.org,
        longman@...hat.com, paulmck@...ux.vnet.ibm.com,
        boqun.feng@...il.com, Yuyang Du <duyuyang@...il.com>
Subject: [PATCH v3 25/30] locking/lockdep: Add nest lock type

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@...il.com>
---
 kernel/locking/lockdep.c           | 7 +++++--
 kernel/locking/lockdep_internals.h | 2 ++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e7610d2..cb3a1d3 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2517,6 +2517,7 @@ static inline void inc_chains(void)
  *  0: on deadlock detected;
  *  1: on OK;
  *  LOCK_TYPE_RECURSIVE: on recursive read
+ *  LOCK_TYPE_NEST: on nest lock
  */
 static int
 check_deadlock_current(struct task_struct *curr, struct held_lock *next)
@@ -2546,7 +2547,7 @@ 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;
@@ -3049,12 +3050,14 @@ static int validate_chain(struct task_struct *curr, struct held_lock *next,
 
 		if (!ret)
 			return 0;
+
 		/*
 		 * Add dependency only if this lock is not the head of the
 		 * chain, and if it's not a second recursive-read lock. If
 		 * not, there is no need to check further.
 		 */
-		if (!(chain->depth > 1 && ret != LOCK_TYPE_RECURSIVE))
+		if (!(chain->depth > 1 && ret != LOCK_TYPE_RECURSIVE &&
+		      ret != LOCK_TYPE_NEST))
 			goto out_unlock;
 	}
 
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index e9a8ed6..56fac83 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -26,6 +26,8 @@ enum lock_usage_bit {
 #define LOCK_USAGE_DIR_MASK  2
 #define LOCK_USAGE_STATE_MASK (~(LOCK_USAGE_READ_MASK | LOCK_USAGE_DIR_MASK))
 
+#define LOCK_TYPE_NEST	NR_LOCK_TYPE
+
 /*
  * Usage-state bitmasks:
  */
-- 
1.8.3.1