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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@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: frederic@kernel.org
Cc: ming.lei@redhat.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190506081939.74287-13-duyuyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yuyang Du 2019-05-06 16:19:28 +08:00 committed by Ingo Molnar
parent 31a490e5c5
commit aa4807719e
1 changed files with 14 additions and 10 deletions
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24
kernel/locking/lockdep.c
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@ -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;
}