Make sure that all lock order entries that refer to a class are removed from the list_entries[] array when a kernel module is unloaded.
Cc: Peter Zijlstra <pet...@infradead.org> Cc: Waiman Long <long...@redhat.com> Cc: Johannes Berg <johan...@sipsolutions.net> Signed-off-by: Bart Van Assche <bvanass...@acm.org> --- include/linux/lockdep.h | 1 + kernel/locking/lockdep.c | 17 +++++++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 1fd82ff99c65..6d0f8d1c2bee 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -180,6 +180,7 @@ static inline void lockdep_copy_map(struct lockdep_map *to, struct lock_list { struct list_head entry; struct lock_class *class; + struct lock_class *links_to; struct stack_trace trace; int distance; diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 5c837a537273..ecd92969674c 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -859,7 +859,8 @@ static struct lock_list *alloc_list_entry(void) /* * Add a new dependency to the head of the list: */ -static int add_lock_to_list(struct lock_class *this, struct list_head *head, +static int add_lock_to_list(struct lock_class *this, + struct lock_class *links_to, struct list_head *head, unsigned long ip, int distance, struct stack_trace *trace) { @@ -872,7 +873,9 @@ static int add_lock_to_list(struct lock_class *this, struct list_head *head, if (!entry) return 0; + WARN_ON_ONCE(this == links_to); entry->class = this; + entry->links_to = links_to; entry->distance = distance; entry->trace = *trace; /* @@ -1918,14 +1921,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, * Ok, all validations passed, add the new lock * to the previous lock's dependency list: */ - ret = add_lock_to_list(hlock_class(next), + ret = add_lock_to_list(hlock_class(next), hlock_class(prev), &hlock_class(prev)->locks_after, next->acquire_ip, distance, trace); if (!ret) return 0; - ret = add_lock_to_list(hlock_class(prev), + ret = add_lock_to_list(hlock_class(prev), hlock_class(next), &hlock_class(next)->locks_before, next->acquire_ip, distance, trace); if (!ret) @@ -4128,15 +4131,17 @@ void lockdep_reset(void) */ static void zap_class(struct lock_class *class) { + struct lock_list *entry; int i; /* * Remove all dependencies this lock is * involved in: */ - for (i = 0; i < nr_list_entries; i++) { - if (list_entries[i].class == class) - list_del_rcu(&list_entries[i].entry); + for (i = 0, entry = list_entries; i < nr_list_entries; i++, entry++) { + if (entry->class != class && entry->links_to != class) + continue; + list_del_rcu(&entry->entry); } /* * Unhash the class and remove it from the all_lock_classes list: -- 2.20.0.rc2.403.gdbc3b29805-goog