[PATCH v3 13/30] locking/lockdep: Combine lock_lists in struct lock_class into an array

Yuyang Du
2019-06-28T09:16:45Z

We are going to combine forward dependency lock_lists and backward
dependency lock_lists. Combing locks_before and locks_after lists, this
patch makes the code after all this a bit clearer.

No functional change.

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
include/linux/lockdep.h | 6 ++---
kernel/locking/lockdep.c | 63 +++++++++++++++++++------------------------
kernel/locking/lockdep_proc.c | 2 +-
3 files changed, 32 insertions(+), 39 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 5e0a1a9..62eba72 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -92,10 +92,10 @@ struct lock_class {

/*
* These fields represent a directed graph of lock dependencies,
- * to every node we attach a list of "forward" and a list of
- * "backward" graph nodes.
+ * to every node we attach a list of "forward" graph nodes
+ * @dep_list[1] and a list of "backward" graph nodes @dep_list[0].
*/
- struct list_head locks_after, locks_before;
+ struct list_head dep_list[2];

struct lockdep_subclass_key *key;
unsigned int subclass;
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 6f457ef..39210a4 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -833,8 +833,7 @@ static bool in_list(struct list_head *e, struct list_head *h)
}

/*
- * Check whether entry @e occurs in any of the locks_after or locks_before
- * lists.
+ * Check whether entry @e occurs in any of the dep lists.
*/
static bool in_any_class_list(struct list_head *e)
{
@@ -843,8 +842,8 @@ static bool in_any_class_list(struct list_head *e)

for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
class = &lock_classes[i];
- if (in_list(e, &class->locks_after) ||
- in_list(e, &class->locks_before))
+ if (in_list(e, &class->dep_list[0]) ||
+ in_list(e, &class->dep_list[1]))
return true;
}
return false;
@@ -932,9 +931,9 @@ static bool __check_data_structures(void)
/* Check whether all classes have valid lock lists. */
for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
class = &lock_classes[i];
- if (!class_lock_list_valid(class, &class->locks_before))
+ if (!class_lock_list_valid(class, &class->dep_list[0]))
return false;
- if (!class_lock_list_valid(class, &class->locks_after))
+ if (!class_lock_list_valid(class, &class->dep_list[1]))
return false;
}

@@ -1030,8 +1029,8 @@ static void init_data_structures_once(void)

for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
- INIT_LIST_HEAD(&lock_classes[i].locks_after);
- INIT_LIST_HEAD(&lock_classes[i].locks_before);
+ INIT_LIST_HEAD(&lock_classes[i].dep_list[0]);
+ INIT_LIST_HEAD(&lock_classes[i].dep_list[1]);
}
}

@@ -1160,8 +1159,8 @@ static bool is_dynamic_key(const struct lock_class_key *key)
class->key = key;
class->name = lock->name;
class->subclass = subclass;
- WARN_ON_ONCE(!list_empty(&class->locks_before));
- WARN_ON_ONCE(!list_empty(&class->locks_after));
+ WARN_ON_ONCE(!list_empty(&class->dep_list[0]));
+ WARN_ON_ONCE(!list_empty(&class->dep_list[1]));
class->name_version = count_matching_names(class);
/*
* We use RCU's safe list-add method to make
@@ -1380,15 +1379,14 @@ static inline int get_lock_depth(struct lock_list *child)
/*
* Return the forward or backward dependency list.
*
- * @lock: the lock_list to get its class's dependency list
- * @offset: the offset to struct lock_class to determine whether it is
- * locks_after or locks_before
+ * @lock: the lock_list to get its class's dependency list
+ * @forward: the forward dep list or backward dep list
*/
-static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
+static inline struct list_head *get_dep_list(struct lock_list *lock, int forward)
{
- void *lock_class = lock->class;
+ struct lock_class *class = lock->class;

- return lock_class + offset;
+ return &class->dep_list[forward];
}

/*
@@ -1398,8 +1396,7 @@ static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
static int __bfs(struct lock_list *source_entry,
void *data,
int (*match)(struct lock_list *entry, void *data),
- struct lock_list **target_entry,
- int offset)
+ struct lock_list **target_entry, int forward)
{
struct lock_list *entry;
struct lock_list *lock;
@@ -1413,7 +1410,7 @@ static int __bfs(struct lock_list *source_entry,
goto exit;
}

- head = get_dep_list(source_entry, offset);
+ head = get_dep_list(source_entry, forward);
if (list_empty(head))
goto exit;

@@ -1427,7 +1424,7 @@ static int __bfs(struct lock_list *source_entry,
goto exit;
}

- head = get_dep_list(lock, offset);
+ head = get_dep_list(lock, forward);

DEBUG_LOCKS_WARN_ON(!irqs_disabled());

@@ -1460,9 +1457,7 @@ static inline int __bfs_forwards(struct lock_list *src_entry,
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
- return __bfs(src_entry, data, match, target_entry,
- offsetof(struct lock_class, locks_after));
-
+ return __bfs(src_entry, data, match, target_entry, 1);
}

static inline int __bfs_backwards(struct lock_list *src_entry,
@@ -1470,9 +1465,7 @@ static inline int __bfs_backwards(struct lock_list *src_entry,
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
- return __bfs(src_entry, data, match, target_entry,
- offsetof(struct lock_class, locks_before));
-
+ return __bfs(src_entry, data, match, target_entry, 0);
}

static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
@@ -2375,7 +2368,7 @@ static inline void inc_chains(void)
* chains - the second one will be new, but L1 already has
* L2 added to its dependency list, due to the first chain.)
*/
- list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
+ list_for_each_entry(entry, &hlock_class(prev)->dep_list[1], entry) {
if (entry->class == hlock_class(next)) {
debug_atomic_inc(nr_redundant);

@@ -2422,14 +2415,14 @@ static inline void inc_chains(void)
* to the previous lock's dependency list:
*/
ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
- &hlock_class(prev)->locks_after,
+ &hlock_class(prev)->dep_list[1],
next->acquire_ip, distance, trace);

if (!ret)
return 0;

ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
- &hlock_class(next)->locks_before,
+ &hlock_class(next)->dep_list[0],
next->acquire_ip, distance, trace);
if (!ret)
return 0;
@@ -4740,8 +4733,8 @@ static void zap_class(struct pending_free *pf, struct lock_class *class)
nr_list_entries--;
list_del_rcu(&entry->entry);
}
- if (list_empty(&class->locks_after) &&
- list_empty(&class->locks_before)) {
+ if (list_empty(&class->dep_list[0]) &&
+ list_empty(&class->dep_list[1])) {
list_move_tail(&class->lock_entry, &pf->zapped);
hlist_del_rcu(&class->hash_entry);
WRITE_ONCE(class->key, NULL);
@@ -4762,12 +4755,12 @@ static void reinit_class(struct lock_class *class)
const unsigned int offset = offsetof(struct lock_class, key);

WARN_ON_ONCE(!class->lock_entry.next);
- WARN_ON_ONCE(!list_empty(&class->locks_after));
- WARN_ON_ONCE(!list_empty(&class->locks_before));
+ WARN_ON_ONCE(!list_empty(&class->dep_list[0]));
+ WARN_ON_ONCE(!list_empty(&class->dep_list[1]));
memset(p + offset, 0, sizeof(*class) - offset);
WARN_ON_ONCE(!class->lock_entry.next);
- WARN_ON_ONCE(!list_empty(&class->locks_after));
- WARN_ON_ONCE(!list_empty(&class->locks_before));
+ WARN_ON_ONCE(!list_empty(&class->dep_list[0]));
+ WARN_ON_ONCE(!list_empty(&class->dep_list[1]));
}

static inline int within(const void *addr, void *start, unsigned long size)
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 58ed889..dc0dfae 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -82,7 +82,7 @@ static int l_show(struct seq_file *m, void *v)
print_name(m, class);
seq_puts(m, "\n");

- list_for_each_entry(entry, &class->locks_after, entry) {
+ list_for_each_entry(entry, &class->dep_list[1], entry) {
if (entry->distance == 1) {
seq_printf(m, " -> [%p] ", entry->class->key);
print_name(m, entry->class);
--
1.8.3.1