Commit-ID: aa4807719e076bfb2dee9c96adf2c648e47d472f
Gitweb: https://git.kernel.org/tip/aa4807719e076bfb2dee9c96adf2c648e47d472f
Author: Yuyang Du <duyuyang@xxxxxxxxx>
AuthorDate: Mon, 6 May 2019 16:19:28 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Jun 2019 11:55:45 +0200
locking/lockdep: Change type of the element field in circular_queue
The element field is an array in struct circular_queue to keep track of locks
in the search. Making it the same type as the locks avoids type cast. Also
fix a typo and elaborate the comment above struct circular_queue.
No functional change.
Signed-off-by: Yuyang Du <duyuyang@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: frederic@xxxxxxxxxx
Cc: ming.lei@xxxxxxxxxx
Cc: will.deacon@xxxxxxx
Link: https://lkml.kernel.org/r/20190506081939.74287-13-duyuyang@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/locking/lockdep.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a9799f9ed093..d467ba825dca 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1262,13 +1262,17 @@ static int add_lock_to_list(struct lock_class *this,
#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
/*
- * The circular_queue and helpers is used to implement the
- * breadth-first search(BFS)algorithem, by which we can build
- * the shortest path from the next lock to be acquired to the
- * previous held lock if there is a circular between them.
+ * The circular_queue and helpers are used to implement graph
+ * breadth-first search (BFS) algorithm, by which we can determine
+ * whether there is a path from a lock to another. In deadlock checks,
+ * a path from the next lock to be acquired to a previous held lock
+ * indicates that adding the <prev> -> <next> lock dependency will
+ * produce a circle in the graph. Breadth-first search instead of
+ * depth-first search is used in order to find the shortest (circular)
+ * path.
*/
struct circular_queue {
- unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
+ struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
unsigned int front, rear;
};
@@ -1294,7 +1298,7 @@ static inline int __cq_full(struct circular_queue *cq)
return ((cq->rear + 1) & CQ_MASK) == cq->front;
}
-static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
+static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
{
if (__cq_full(cq))
return -1;
@@ -1304,7 +1308,7 @@ static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
return 0;
}
-static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
+static inline int __cq_dequeue(struct circular_queue *cq, struct lock_list **elem)
{
if (__cq_empty(cq))
return -1;
@@ -1382,12 +1386,12 @@ static int __bfs(struct lock_list *source_entry,
goto exit;
__cq_init(cq);
- __cq_enqueue(cq, (unsigned long)source_entry);
+ __cq_enqueue(cq, source_entry);
while (!__cq_empty(cq)) {
struct lock_list *lock;
- __cq_dequeue(cq, (unsigned long *)&lock);
+ __cq_dequeue(cq, &lock);
if (!lock->class) {
ret = -2;
@@ -1411,7 +1415,7 @@ static int __bfs(struct lock_list *source_entry,
goto exit;
}
- if (__cq_enqueue(cq, (unsigned long)entry)) {
+ if (__cq_enqueue(cq, entry)) {
ret = -1;
goto exit;
}
|