The following commit has been merged into the locking/core branch of tip:
Commit-ID: bc2dd71b283665f0a409d5b6fc603d5a6fdc219e
Gitweb: https://git.kernel.org/tip/bc2dd71b283665f0a409d5b6fc603d5a6fdc219e
Author: Boqun Feng <boqun.feng@xxxxxxxxx>
AuthorDate: Thu, 10 Dec 2020 11:02:40 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 14 Jan 2021 11:20:17 +01:00
locking/lockdep: Add a skip() function to __bfs()
Some __bfs() walks will have additional iteration constraints (beyond
the path being strong). Provide an additional function to allow
terminating graph walks.
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
kernel/locking/lockdep.c | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index b061e29..f50f026 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1672,6 +1672,7 @@ static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset)
static enum bfs_result __bfs(struct lock_list *source_entry,
void *data,
bool (*match)(struct lock_list *entry, void *data),
+ bool (*skip)(struct lock_list *entry, void *data),
struct lock_list **target_entry,
int offset)
{
@@ -1732,7 +1733,12 @@ static enum bfs_result __bfs(struct lock_list *source_entry,
/*
* Step 3: we haven't visited this and there is a strong
* dependency path to this, so check with @match.
+ * If @skip is provide and returns true, we skip this
+ * lock (and any path this lock is in).
*/
+ if (skip && skip(lock, data))
+ continue;
+
if (match(lock, data)) {
*target_entry = lock;
return BFS_RMATCH;
@@ -1775,9 +1781,10 @@ static inline enum bfs_result
__bfs_forwards(struct lock_list *src_entry,
void *data,
bool (*match)(struct lock_list *entry, void *data),
+ bool (*skip)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
- return __bfs(src_entry, data, match, target_entry,
+ return __bfs(src_entry, data, match, skip, target_entry,
offsetof(struct lock_class, locks_after));
}
@@ -1786,9 +1793,10 @@ static inline enum bfs_result
__bfs_backwards(struct lock_list *src_entry,
void *data,
bool (*match)(struct lock_list *entry, void *data),
+ bool (*skip)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
- return __bfs(src_entry, data, match, target_entry,
+ return __bfs(src_entry, data, match, skip, target_entry,
offsetof(struct lock_class, locks_before));
}
@@ -2019,7 +2027,7 @@ static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
unsigned long count = 0;
struct lock_list *target_entry;
- __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
+ __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
return count;
}
@@ -2044,7 +2052,7 @@ static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
unsigned long count = 0;
struct lock_list *target_entry;
- __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
+ __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
return count;
}
@@ -2072,11 +2080,12 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class)
static noinline enum bfs_result
check_path(struct held_lock *target, struct lock_list *src_entry,
bool (*match)(struct lock_list *entry, void *data),
+ bool (*skip)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
enum bfs_result ret;
- ret = __bfs_forwards(src_entry, target, match, target_entry);
+ ret = __bfs_forwards(src_entry, target, match, skip, target_entry);
if (unlikely(bfs_error(ret)))
print_bfs_bug(ret);
@@ -2103,7 +2112,7 @@ check_noncircular(struct held_lock *src, struct held_lock *target,
debug_atomic_inc(nr_cyclic_checks);
- ret = check_path(target, &src_entry, hlock_conflict, &target_entry);
+ ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry);
if (unlikely(ret == BFS_RMATCH)) {
if (!*trace) {
@@ -2152,7 +2161,7 @@ check_redundant(struct held_lock *src, struct held_lock *target)
debug_atomic_inc(nr_redundant_checks);
- ret = check_path(target, &src_entry, hlock_equal, &target_entry);
+ ret = check_path(target, &src_entry, hlock_equal, NULL, &target_entry);
if (ret == BFS_RMATCH)
debug_atomic_inc(nr_redundant);
@@ -2246,7 +2255,7 @@ find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
debug_atomic_inc(nr_find_usage_forwards_checks);
- result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
+ result = __bfs_forwards(root, &usage_mask, usage_match, NULL, target_entry);
return result;
}
@@ -2263,7 +2272,7 @@ find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
debug_atomic_inc(nr_find_usage_backwards_checks);
- result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
+ result = __bfs_backwards(root, &usage_mask, usage_match, NULL, target_entry);
return result;
}
@@ -2628,7 +2637,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
*/
bfs_init_rootb(&this, prev);
- ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
+ ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL, NULL);
if (bfs_error(ret)) {
print_bfs_bug(ret);
return 0;
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