Instead of abandoning elements of list_entries[] that are no longer in use, make alloc_list_entry() reuse array elements that have been freed.
Signed-off-by: Bart Van Assche <[email protected]> --- include/linux/lockdep.h | 5 +++++ kernel/locking/lockdep.c | 23 ++++++++++++++++------- 2 files changed, 21 insertions(+), 7 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 43327a1dd488..01e55fca7c2c 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -183,6 +183,11 @@ static inline void lockdep_copy_map(struct lockdep_map *to, struct lock_list { /* Entry in locks_after or locks_before. */ struct list_head lock_order_entry; + /* + * Entry in all_list_entries when in use and entry in + * free_list_entries when not in use. + */ + struct list_head alloc_entry; struct lock_class *class; struct lock_class *links_to; struct stack_trace trace; diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 038377d67410..288a2f6fd0ef 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -130,6 +130,8 @@ static inline int debug_locks_off_graph_unlock(void) unsigned long nr_list_entries; static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; +static LIST_HEAD(all_list_entries); +static LIST_HEAD(free_list_entries); /* * All data structures here are protected by the global debug_lock. @@ -743,6 +745,9 @@ static void init_lists(void) INIT_LIST_HEAD(&lock_classes[i].locks_after); INIT_LIST_HEAD(&lock_classes[i].locks_before); } + + for (i = 0; i < ARRAY_SIZE(list_entries); i++) + list_add_tail(&list_entries[i].alloc_entry, &free_list_entries); } /* @@ -862,7 +867,10 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) */ static struct lock_list *alloc_list_entry(void) { - if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { + struct lock_list *e = list_first_entry_or_null(&free_list_entries, + typeof(*e), alloc_entry); + + if (!e) { if (!debug_locks_off_graph_unlock()) return NULL; @@ -870,7 +878,8 @@ static struct lock_list *alloc_list_entry(void) dump_stack(); return NULL; } - return list_entries + nr_list_entries++; + list_move_tail(&e->alloc_entry, &all_list_entries); + return e; } /* @@ -975,7 +984,7 @@ static inline void mark_lock_accessed(struct lock_list *lock, unsigned long nr; nr = lock - list_entries; - WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ lock->parent = parent; lock->class->dep_gen_id = lockdep_dependency_gen_id; } @@ -985,7 +994,7 @@ static inline unsigned long lock_accessed(struct lock_list *lock) unsigned long nr; nr = lock - list_entries; - WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ return lock->class->dep_gen_id == lockdep_dependency_gen_id; } @@ -4235,19 +4244,19 @@ static void zap_class(struct list_head *zapped_classes, struct lock_class *class) { struct lock_class *links_to; - struct lock_list *entry; - int i; + struct lock_list *entry, *tmp; /* * Remove all dependencies this lock is * involved in: */ - for (i = 0, entry = list_entries; i < nr_list_entries; i++, entry++) { + list_for_each_entry_safe(entry, tmp, &all_list_entries, alloc_entry) { if (entry->class != class && entry->links_to != class) continue; links_to = entry->links_to; WARN_ON_ONCE(entry->class == links_to); list_del_rcu(&entry->lock_order_entry); + list_move(&entry->alloc_entry, &free_list_entries); entry->class = NULL; entry->links_to = NULL; check_free_class(zapped_classes, class); -- 2.20.0.rc0.387.gc7a69e6b6c-goog
