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From: Yuyang Du <duyuyang@gmail.com>
To: peterz@infradead.org, will.deacon@arm.com, mingo@kernel.org
Cc: bvanassche@acm.org, ming.lei@redhat.com,
	linux-kernel@vger.kernel.org, joe@perches.com,
	Yuyang Du <duyuyang@gmail.com>
Subject: [PATCH v3 14/18] locking/lockdep: Change the return type of __cq_dequeue()
Date: Thu, 21 Mar 2019 15:57:21 +0800	[thread overview]
Message-ID: <20190321075725.14054-15-duyuyang@gmail.com> (raw)
In-Reply-To: <20190321075725.14054-1-duyuyang@gmail.com>

With the change, we can slightly adjust the code to iterate the queue in BFS
search, which simplifies the code. No functional change.

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
 kernel/locking/lockdep.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 8167d69..ad16793 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1317,14 +1317,21 @@ static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem
 	return 0;
 }
 
-static inline int __cq_dequeue(struct circular_queue *cq, struct lock_list **elem)
+/*
+ * Dequeue an element from the circular_queue, return the lock if the queue
+ * is not empty, or NULL if otherwise
+ */
+static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
 {
+	struct lock_list * lock;
+
 	if (__cq_empty(cq))
-		return -1;
+		return NULL;
 
-	*elem = cq->element[cq->front];
+	lock = cq->element[cq->front];
 	cq->front = (cq->front + 1) & CQ_MASK;
-	return 0;
+
+	return lock;
 }
 
 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
@@ -1376,6 +1383,7 @@ static int __bfs(struct lock_list *source_entry,
 		 int forward)
 {
 	struct lock_list *entry;
+	struct lock_list *lock;
 	struct list_head *head;
 	struct circular_queue *cq = &lock_cq;
 	int ret = 1;
@@ -1397,10 +1405,7 @@ static int __bfs(struct lock_list *source_entry,
 	__cq_init(cq);
 	__cq_enqueue(cq, source_entry);
 
-	while (!__cq_empty(cq)) {
-		struct lock_list *lock;
-
-		__cq_dequeue(cq, &lock);
+	while ((lock = __cq_dequeue(cq))) {
 
 		if (!lock->class) {
 			ret = -2;
-- 
1.8.3.1


  parent reply	other threads:[~2019-03-21  7:58 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-21  7:57 [PATCH v3 00/18] locking/lockdep: Add comments and make some code Yuyang Du
2019-03-21  7:57 ` [PATCH v3 01/18] locking/lockdep: Change all print_*() return type to void Yuyang Du
2019-03-21  7:57 ` [PATCH v3 02/18] locking/lockdep: Add description and explanation in lockdep design doc Yuyang Du
2019-03-21  7:57 ` [PATCH v3 03/18] locking/lockdep: Adjust lock usage bit character checks Yuyang Du
2019-03-21  7:57 ` [PATCH v3 04/18] locking/lockdep: Remove useless conditional macro Yuyang Du
2019-03-21  7:57 ` [PATCH v3 05/18] locking/lockdep: Print the right depth for chain key colission Yuyang Du
2019-03-21  7:57 ` [PATCH v3 06/18] locking/lockdep: Update obsolete struct field description Yuyang Du
2019-03-21  7:57 ` [PATCH v3 07/18] locking/lockdep: Use lockdep_init_task for task initiation consistently Yuyang Du
2019-03-21  7:57 ` [PATCH v3 08/18] locking/lockdep: Define INITIAL_CHAIN_KEY for chain keys to start with Yuyang Du
2019-03-21  7:57 ` [PATCH v3 09/18] locking/lockdep: Change the range of class_idx in held_lock struct Yuyang Du
2019-03-21  7:57 ` [PATCH v3 10/18] locking/lockdep: Remove unused argument in validate_chain() and check_deadlock() Yuyang Du
2019-03-21  7:57 ` [PATCH v3 11/18] locking/lockdep: Update comment Yuyang Du
2019-03-21  7:57 ` [PATCH v3 12/18] locking/lockdep: Remove unnecessary function pointer argument Yuyang Du
2019-03-21  7:57 ` [PATCH v3 13/18] locking/lockdep: Change type of the element field in circular_queue Yuyang Du
2019-03-21  7:57 ` Yuyang Du [this message]
2019-03-21  7:57 ` [PATCH v3 15/18] locking/lockdep: Avoid constant checks in __bfs by using offset reference Yuyang Du
2019-03-21  7:57 ` [PATCH v3 16/18] locking/lockdep: Combine check_noncircular and check_redundant Yuyang Du
2019-03-21  7:57 ` [PATCH v3 17/18] locking/lockdep: Update comments on dependency search Yuyang Du
2019-03-21  7:57 ` [PATCH v3 18/18] locking/lockdep: Add explanation to lock usage rules in lockdep design doc Yuyang Du
2019-04-04  5:03   ` Question on a lockdep test case about mixed read-write ABBA Yuyang Du

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