diff options
| -rw-r--r-- | include/linux/lockdep.h | 6 | ||||
| -rw-r--r-- | kernel/lockdep.c | 115 | ||||
| -rw-r--r-- | kernel/lockdep_internals.h | 83 |
3 files changed, 195 insertions, 9 deletions
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index b25d1b53df0..9ec026f8d09 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -149,6 +149,12 @@ struct lock_list { struct lock_class *class; struct stack_trace trace; int distance; + + /*The parent field is used to implement breadth-first search,and + *the bit 0 is reused to indicate if the lock has been accessed + *in BFS. + */ + struct lock_list *parent; }; /* diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 8bbeef996c7..93dc70d18cd 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -897,6 +897,79 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this, return 1; } +static struct circular_queue lock_cq; +static int __search_shortest_path(struct lock_list *source_entry, + struct lock_class *target, + struct lock_list **target_entry, + int forward) +{ + struct lock_list *entry; + struct circular_queue *cq = &lock_cq; + int ret = 1; + + __cq_init(cq); + + mark_lock_accessed(source_entry, NULL); + if (source_entry->class == target) { + *target_entry = source_entry; + ret = 0; + goto exit; + } + + __cq_enqueue(cq, (unsigned long)source_entry); + + while (!__cq_empty(cq)) { + struct lock_list *lock; + struct list_head *head; + + __cq_dequeue(cq, (unsigned long *)&lock); + + if (!lock->class) { + ret = -2; + goto exit; + } + + if (forward) + head = &lock->class->locks_after; + else + head = &lock->class->locks_before; + + list_for_each_entry(entry, head, entry) { + if (!lock_accessed(entry)) { + mark_lock_accessed(entry, lock); + if (entry->class == target) { + *target_entry = entry; + ret = 0; + goto exit; + } + + if (__cq_enqueue(cq, (unsigned long)entry)) { + ret = -1; + goto exit; + } + } + } + } +exit: + return ret; +} + +static inline int __search_forward_shortest_path(struct lock_list *src_entry, + struct lock_class *target, + struct lock_list **target_entry) +{ + return __search_shortest_path(src_entry, target, target_entry, 1); + +} + +static inline int __search_backward_shortest_path(struct lock_list *src_entry, + struct lock_class *target, + struct lock_list **target_entry) +{ + return __search_shortest_path(src_entry, target, target_entry, 0); + +} + /* * Recursive, forwards-direction lock-dependency checking, used for * both noncyclic checking and for hardirq-unsafe/softirq-unsafe @@ -934,7 +1007,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth) { struct task_struct *curr = current; - if (!debug_locks_off_graph_unlock() || debug_locks_silent) + if (debug_locks_silent) return 0; printk("\n=======================================================\n"); @@ -954,19 +1027,41 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth) return 0; } -static noinline int print_circular_bug_tail(void) +static noinline int print_circular_bug(void) { struct task_struct *curr = current; struct lock_list this; + struct lock_list *target; + struct lock_list *parent; + int result; + unsigned long depth; - if (debug_locks_silent) + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; this.class = hlock_class(check_source); if (!save_trace(&this.trace)) return 0; - print_circular_bug_entry(&this, 0); + result = __search_forward_shortest_path(&this, + hlock_class(check_target), + &target); + if (result) { + printk("\n%s:search shortest path failed:%d\n", __func__, + result); + return 0; + } + + depth = get_lock_depth(target); + + print_circular_bug_header(target, depth); + + parent = get_lock_parent(target); + + while (parent) { + print_circular_bug_entry(parent, --depth); + parent = get_lock_parent(parent); + } printk("\nother info that might help us debug this:\n\n"); lockdep_print_held_locks(curr); @@ -1072,14 +1167,15 @@ check_noncircular(struct lock_class *source, unsigned int depth) */ list_for_each_entry(entry, &source->locks_after, entry) { if (entry->class == hlock_class(check_target)) - return print_circular_bug_header(entry, depth+1); + return 2; debug_atomic_inc(&nr_cyclic_checks); - if (!check_noncircular(entry->class, depth+1)) - return print_circular_bug_entry(entry, depth+1); + if (check_noncircular(entry->class, depth+1) == 2) + return 2; } return 1; } + #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) /* * Forwards and backwards subgraph searching, for the purposes of @@ -1484,8 +1580,9 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, */ check_source = next; check_target = prev; - if (!(check_noncircular(hlock_class(next), 0))) - return print_circular_bug_tail(); + if (check_noncircular(hlock_class(next), 0) == 2) + return print_circular_bug(); + if (!check_prev_add_irq(curr, prev, next)) return 0; diff --git a/kernel/lockdep_internals.h b/kernel/lockdep_internals.h index 699a2ac3a0d..6f48d37d5be 100644 --- a/kernel/lockdep_internals.h +++ b/kernel/lockdep_internals.h @@ -136,3 +136,86 @@ extern atomic_t nr_find_usage_backwards_recursions; # define debug_atomic_dec(ptr) do { } while (0) # define debug_atomic_read(ptr) 0 #endif + +/* The circular_queue and helpers is used to implement the + * breadth-first search(BFS)algorithem, by which we can build + * the shortest path from the next lock to be acquired to the + * previous held lock if there is a circular between them. + * */ +#define MAX_CIRCULAR_QUE_SIZE 4096UL +struct circular_queue{ + unsigned long element[MAX_CIRCULAR_QUE_SIZE]; + unsigned int front, rear; +}; + +#define LOCK_ACCESSED 1UL +#define LOCK_ACCESSED_MASK (~LOCK_ACCESSED) + +static inline void __cq_init(struct circular_queue *cq) +{ + cq->front = cq->rear = 0; +} + +static inline int __cq_empty(struct circular_queue *cq) +{ + return (cq->front == cq->rear); +} + +static inline int __cq_full(struct circular_queue *cq) +{ + return ((cq->rear + 1)%MAX_CIRCULAR_QUE_SIZE) == cq->front; +} + +static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) +{ + if (__cq_full(cq)) + return -1; + + cq->element[cq->rear] = elem; + cq->rear = (cq->rear + 1)%MAX_CIRCULAR_QUE_SIZE; + return 0; +} + +static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) +{ + if (__cq_empty(cq)) + return -1; + + *elem = cq->element[cq->front]; + cq->front = (cq->front + 1)%MAX_CIRCULAR_QUE_SIZE; + return 0; +} + +static inline int __cq_get_elem_count(struct circular_queue *cq) +{ + return (cq->rear - cq->front)%MAX_CIRCULAR_QUE_SIZE; +} + +static inline void mark_lock_accessed(struct lock_list *lock, + struct lock_list *parent) +{ + lock->parent = (void *) parent + LOCK_ACCESSED; +} + +static inline unsigned long lock_accessed(struct lock_list *lock) +{ + return (unsigned long)lock->parent & LOCK_ACCESSED; +} + +static inline struct lock_list *get_lock_parent(struct lock_list *child) +{ + return (struct lock_list *) + ((unsigned long)child->parent & LOCK_ACCESSED_MASK); +} + +static inline unsigned long get_lock_depth(struct lock_list *child) +{ + unsigned long depth = 0; + struct lock_list *parent; + + while ((parent = get_lock_parent(child))) { + child = parent; + depth++; + } + return depth; +} |