Instead of abandoning elements of list_entries[] that are no longer in use, make alloc_list_entry() reuse array elements that have been freed.
Cc: Peter Zijlstra <[email protected]> Cc: Waiman Long <[email protected]> Cc: Johannes Berg <[email protected]> Signed-off-by: Bart Van Assche <[email protected]> --- kernel/locking/lockdep.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index ce8abd268727..6f338f852f7e 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 DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); +static DECLARE_BITMAP(list_entries_being_freed, MAX_LOCKDEP_ENTRIES); /* * All data structures here are protected by the global debug_lock. @@ -870,7 +872,10 @@ 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) { + int idx = find_first_zero_bit(list_entries_in_use, + ARRAY_SIZE(list_entries)); + + if (idx >= ARRAY_SIZE(list_entries)) { if (!debug_locks_off_graph_unlock()) return NULL; @@ -878,7 +883,8 @@ static struct lock_list *alloc_list_entry(void) dump_stack(); return NULL; } - return list_entries + nr_list_entries++; + __set_bit(idx, list_entries_in_use); + return list_entries + idx; } /* @@ -983,7 +989,7 @@ 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; } @@ -993,7 +999,7 @@ 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; } @@ -4252,9 +4258,12 @@ static void zap_class(struct lock_class *class) * Remove all dependencies this lock is * involved in: */ - for (i = 0, entry = list_entries; i < nr_list_entries; i++, entry++) { + for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { + entry = list_entries + i; if (entry->class != class && entry->links_to != class) continue; + if (__test_and_set_bit(i, list_entries_being_freed)) + continue; links_to = entry->links_to; WARN_ON_ONCE(entry->class == links_to); list_del_rcu(&entry->entry); @@ -4287,8 +4296,9 @@ static inline int within(const void *addr, void *start, unsigned long size) } /* - * Free all lock classes that are on the zapped_classes list. Called as an - * RCU callback function. + * Free all lock classes that are on the zapped_classes list and also all list + * entries that have been marked as being freed. Called as an RCU callback + * function. */ static void free_zapped_classes(struct callback_head *ch) { @@ -4304,6 +4314,9 @@ static void free_zapped_classes(struct callback_head *ch) nr_lock_classes--; } list_splice_init(&zapped_classes, &free_lock_classes); + bitmap_andnot(list_entries_in_use, list_entries_in_use, + list_entries_being_freed, ARRAY_SIZE(list_entries)); + bitmap_clear(list_entries_being_freed, 0, ARRAY_SIZE(list_entries)); if (locked) graph_unlock(); raw_local_irq_restore(flags); -- 2.20.0.rc2.403.gdbc3b29805-goog
