Debugging lockdep data structure inconsistencies is challenging. Add disabled code that verifies data structure consistency at runtime.
Signed-off-by: Bart Van Assche <[email protected]> --- kernel/locking/lockdep.c | 142 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 288a2f6fd0ef..141bb0662ff5 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -72,6 +72,8 @@ module_param(lock_stat, int, 0644); #define lock_stat 0 #endif +static bool check_data_structure_consistency; + /* * lockdep_lock: protects the lockdep graph, the hashes and the * class/list/hash allocators. @@ -736,6 +738,135 @@ static bool assign_lock_key(struct lockdep_map *lock) return true; } +/* Check whether element @e occurs in list @h */ +static bool in_list(struct list_head *e, struct list_head *h) +{ + struct list_head *f; + + list_for_each(f, h) + if (e == f) + return true; + + return false; +} + +/* + * Check whether entry @e occurs in any of the locks_after or locks_before + * lists. + */ +static bool in_any_class_list(struct list_head *e) +{ + struct lock_class *class; + int i; + + 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)) + return true; + } + return false; +} + +static bool class_lock_list_valid(struct lock_class *c, struct list_head *h) +{ + struct lock_list *e; + + list_for_each_entry(e, h, lock_order_entry) { + if (e->links_to != c) { + printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s", + c->name ? : "(?)", e - list_entries, + e->links_to && e->links_to->name ? + e->links_to->name : "(?)", + e->class && e->class->name ? e->class->name : + "(?)"); + return false; + } + } + return true; +} + +static u16 chain_hlocks[]; + +static bool check_lock_chain_key(struct lock_chain *chain) +{ + u64 chain_key = 0; + int i; + + for (i = chain->base; i < chain->base + chain->depth; i++) + chain_key = iterate_chain_key(chain_key, chain_hlocks[i] + 1); + /* + * The 'unsigned long long' casts avoid that a compiler warning + * is reported when building tools/lib/lockdep. + */ + if (chain->chain_key != chain_key) + printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n", + (unsigned long long)(chain - lock_chains), + (unsigned long long)chain->chain_key, + (unsigned long long)chain_key); + return chain->chain_key == chain_key; +} + +static bool check_data_structures(void) +{ + struct lock_class *class; + struct lock_chain *chain; + struct hlist_head *head; + struct lock_list *e; + int i; + + /* + * Check whether all list entries that are in use occur in a class + * lock list. + */ + list_for_each_entry(e, &all_list_entries, alloc_entry) { + if (!in_any_class_list(&e->lock_order_entry)) { + printk(KERN_INFO "list entry %ld is not in any class list; class %s <> %s\n", + e - list_entries, + e->class->name ? : "(?)", + e->links_to->name ? : "(?)"); + return false; + } + } + + /* + * Check whether all list entries that are not in use do not occur in + * a class lock list. + */ + list_for_each_entry(e, &free_list_entries, alloc_entry) { + if (in_any_class_list(&e->lock_order_entry)) { + printk(KERN_INFO "list entry %ld occurs in a class list; class %s <> %s\n", + e - list_entries, + e->class && e->class->name ? e->class->name : + "(?)", + e->links_to && e->links_to->name ? + e->links_to->name : "(?)"); + return false; + } + } + + /* Check whether all classes have valid lock lists. */ + for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { + class = &lock_classes[i]; + if (!class->locks_before.next) + continue; + if (!class_lock_list_valid(class, &class->locks_before)) + return false; + if (!class_lock_list_valid(class, &class->locks_after)) + return false; + } + + /* Check the chain_key of all lock chains. */ + for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { + head = chainhash_table + i; + hlist_for_each_entry_rcu(chain, head, entry) + if (!check_lock_chain_key(chain)) + return false; + } + + return true; +} + static void init_lists(void) { int i; @@ -4294,6 +4425,14 @@ static void free_zapped_classes(struct list_head *zapped_classes) unsigned long flags; int locked; + raw_local_irq_save(flags); + locked = graph_lock(); + if (check_data_structure_consistency) + WARN_ON_ONCE(!check_data_structures()); + if (locked) + graph_unlock(); + raw_local_irq_restore(flags); + if (list_empty(zapped_classes)) return; @@ -4314,6 +4453,9 @@ static void free_zapped_classes(struct list_head *zapped_classes) if (locked) graph_unlock(); raw_local_irq_restore(flags); + + if (check_data_structure_consistency) + WARN_ON_ONCE(!check_data_structures()); } /* -- 2.20.0.rc0.387.gc7a69e6b6c-goog
