linux-kernel - [PATCH v2 13/17] locking/lockdep: Add nest lock type

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Date:   Thu, 16 May 2019 16:00:11 +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, boqun.feng@...il.com, paulmck@...ux.ibm.com,
        linux-kernel@...r.kernel.org, Yuyang Du <duyuyang@...il.com>
Subject: [PATCH v2 13/17] 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 | 1 +
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ce79b5a..d8e484d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2527,6 +2527,7 @@ static inline void inc_chains(void)
  *  0: on deadlock detected;
  *  1: on OK;
  *  3: LOCK_TYPE_RECURSIVE on recursive read
+ *  4: LOCK_TYPE_NEST on nest lock
  */
 static int
 check_deadlock_current(struct task_struct *curr, struct held_lock *next)
@@ -2556,7 +2557,7 @@ 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;
@@ -3131,11 +3132,13 @@ 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..759e740 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	(LOCK_TYPE_RECURSIVE + 1)
 
 /*
  * Usage-state bitmasks:
-- 
1.8.3.1