diff options
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/lockdep.c | 137 | ||||
| -rw-r--r-- | kernel/locking/mutex-debug.c | 4 | ||||
| -rw-r--r-- | kernel/locking/mutex-debug.h | 2 | ||||
| -rw-r--r-- | kernel/locking/mutex.c | 24 | ||||
| -rw-r--r-- | kernel/locking/mutex.h | 4 | ||||
| -rw-r--r-- | kernel/locking/rtmutex.c | 4 | ||||
| -rw-r--r-- | kernel/locking/rwsem.c | 2 |
7 files changed, 148 insertions, 29 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 48d736aa03b2..e97d08001437 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -760,7 +760,7 @@ static void lockdep_print_held_locks(struct task_struct *p) * It's not reliable to print a task's held locks if it's not sleeping * and it's not the current task. */ - if (p->state == TASK_RUNNING && p != current) + if (p != current && task_is_running(p)) return; for (i = 0; i < depth; i++) { printk(" #%d: ", i); @@ -843,7 +843,7 @@ static int count_matching_names(struct lock_class *new_class) } /* used from NMI context -- must be lockless */ -static __always_inline struct lock_class * +static noinstr struct lock_class * look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) { struct lockdep_subclass_key *key; @@ -851,12 +851,14 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) struct lock_class *class; if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { + instrumentation_begin(); debug_locks_off(); printk(KERN_ERR "BUG: looking up invalid subclass: %u\n", subclass); printk(KERN_ERR "turning off the locking correctness validator.\n"); dump_stack(); + instrumentation_end(); return NULL; } @@ -2304,7 +2306,56 @@ static void print_lock_class_header(struct lock_class *class, int depth) } /* - * printk the shortest lock dependencies from @start to @end in reverse order: + * Dependency path printing: + * + * After BFS we get a lock dependency path (linked via ->parent of lock_list), + * printing out each lock in the dependency path will help on understanding how + * the deadlock could happen. Here are some details about dependency path + * printing: + * + * 1) A lock_list can be either forwards or backwards for a lock dependency, + * for a lock dependency A -> B, there are two lock_lists: + * + * a) lock_list in the ->locks_after list of A, whose ->class is B and + * ->links_to is A. In this case, we can say the lock_list is + * "A -> B" (forwards case). + * + * b) lock_list in the ->locks_before list of B, whose ->class is A + * and ->links_to is B. In this case, we can say the lock_list is + * "B <- A" (bacwards case). + * + * The ->trace of both a) and b) point to the call trace where B was + * acquired with A held. + * + * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't + * represent a certain lock dependency, it only provides an initial entry + * for BFS. For example, BFS may introduce a "helper" lock_list whose + * ->class is A, as a result BFS will search all dependencies starting with + * A, e.g. A -> B or A -> C. + * + * The notation of a forwards helper lock_list is like "-> A", which means + * we should search the forwards dependencies starting with "A", e.g A -> B + * or A -> C. + * + * The notation of a bacwards helper lock_list is like "<- B", which means + * we should search the backwards dependencies ending with "B", e.g. + * B <- A or B <- C. + */ + +/* + * printk the shortest lock dependencies from @root to @leaf in reverse order. + * + * We have a lock dependency path as follow: + * + * @root @leaf + * | | + * V V + * ->parent ->parent + * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list | + * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln| + * + * , so it's natural that we start from @leaf and print every ->class and + * ->trace until we reach the @root. */ static void __used print_shortest_lock_dependencies(struct lock_list *leaf, @@ -2332,6 +2383,61 @@ print_shortest_lock_dependencies(struct lock_list *leaf, } while (entry && (depth >= 0)); } +/* + * printk the shortest lock dependencies from @leaf to @root. + * + * We have a lock dependency path (from a backwards search) as follow: + * + * @leaf @root + * | | + * V V + * ->parent ->parent + * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list | + * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln | + * + * , so when we iterate from @leaf to @root, we actually print the lock + * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order. + * + * Another thing to notice here is that ->class of L2 <- L1 is L1, while the + * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call + * trace of L1 in the dependency path, which is alright, because most of the + * time we can figure out where L1 is held from the call trace of L2. + */ +static void __used +print_shortest_lock_dependencies_backwards(struct lock_list *leaf, + struct lock_list *root) +{ + struct lock_list *entry = leaf; + const struct lock_trace *trace = NULL; + int depth; + + /*compute depth from generated tree by BFS*/ + depth = get_lock_depth(leaf); + + do { + print_lock_class_header(entry->class, depth); + if (trace) { + printk("%*s ... acquired at:\n", depth, ""); + print_lock_trace(trace, 2); + printk("\n"); + } + + /* + * Record the pointer to the trace for the next lock_list + * entry, see the comments for the function. + */ + trace = entry->trace; + + if (depth == 0 && (entry != root)) { + printk("lockdep:%s bad path found in chain graph\n", __func__); + break; + } + + entry = get_lock_parent(entry); + depth--; + } while (entry && (depth >= 0)); +} + static void print_irq_lock_scenario(struct lock_list *safe_entry, struct lock_list *unsafe_entry, @@ -2446,10 +2552,7 @@ print_bad_irq_dependency(struct task_struct *curr, lockdep_print_held_locks(curr); pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); - prev_root->trace = save_trace(); - if (!prev_root->trace) - return; - print_shortest_lock_dependencies(backwards_entry, prev_root); + print_shortest_lock_dependencies_backwards(backwards_entry, prev_root); pr_warn("\nthe dependencies between the lock to be acquired"); pr_warn(" and %s-irq-unsafe lock:\n", irqclass); @@ -2667,8 +2770,18 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, * Step 3: we found a bad match! Now retrieve a lock from the backward * list whose usage mask matches the exclusive usage mask from the * lock found on the forward list. + * + * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering + * the follow case: + * + * When trying to add A -> B to the graph, we find that there is a + * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M, + * that B -> ... -> M. However M is **softirq-safe**, if we use exact + * invert bits of M's usage_mask, we will find another lock N that is + * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not + * cause a inversion deadlock. */ - backward_mask = original_mask(target_entry1->class->usage_mask); + backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL); ret = find_usage_backwards(&this, backward_mask, &target_entry); if (bfs_error(ret)) { @@ -2718,7 +2831,7 @@ static inline bool usage_skip(struct lock_list *entry, void *mask) * <target> or not. If it can, <src> -> <target> dependency is already * in the graph. * - * Return BFS_RMATCH if it does, or BFS_RMATCH if it does not, return BFS_E* if + * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if * any error appears in the bfs search. */ static noinline enum bfs_result @@ -4577,7 +4690,7 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next) u8 curr_inner; int depth; - if (!curr->lockdep_depth || !next_inner || next->trylock) + if (!next_inner || next->trylock) return 0; if (!next_outer) @@ -5736,7 +5849,7 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; - trace_lock_acquired(lock, ip); + trace_lock_contended(lock, ip); if (unlikely(!lock_stat || !lockdep_enabled())) return; @@ -5754,7 +5867,7 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; - trace_lock_contended(lock, ip); + trace_lock_acquired(lock, ip); if (unlikely(!lock_stat || !lockdep_enabled())) return; diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index a7276aaf2abc..db9301591e3f 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -57,7 +57,7 @@ void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, task->blocked_on = waiter; } -void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, +void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, struct task_struct *task) { DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); @@ -65,7 +65,7 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter); task->blocked_on = NULL; - list_del_init(&waiter->list); + INIT_LIST_HEAD(&waiter->list); waiter->task = NULL; } diff --git a/kernel/locking/mutex-debug.h b/kernel/locking/mutex-debug.h index 1edd3f45a4ec..53e631e1d76d 100644 --- a/kernel/locking/mutex-debug.h +++ b/kernel/locking/mutex-debug.h @@ -22,7 +22,7 @@ extern void debug_mutex_free_waiter(struct mutex_waiter *waiter); extern void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, struct task_struct *task); -extern void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, +extern void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, struct task_struct *task); extern void debug_mutex_unlock(struct mutex *lock); extern void debug_mutex_init(struct mutex *lock, const char *name, diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index cb6b112ce155..d2df5e68b503 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -194,7 +194,7 @@ static inline bool __mutex_waiter_is_first(struct mutex *lock, struct mutex_wait * Add @waiter to a given location in the lock wait_list and set the * FLAG_WAITERS flag if it's the first waiter. */ -static void __sched +static void __mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, struct list_head *list) { @@ -205,6 +205,16 @@ __mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, __mutex_set_flag(lock, MUTEX_FLAG_WAITERS); } +static void +__mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter) +{ + list_del(&waiter->list); + if (likely(list_empty(&lock->wait_list))) + __mutex_clear_flag(lock, MUTEX_FLAGS); + + debug_mutex_remove_waiter(lock, waiter, current); +} + /* * Give up ownership to a specific task, when @task = NULL, this is equivalent * to a regular unlock. Sets PICKUP on a handoff, clears HANDOFF, preserves @@ -913,7 +923,7 @@ __ww_mutex_add_waiter(struct mutex_waiter *waiter, * Lock a mutex (possibly interruptible), slowpath: */ static __always_inline int __sched -__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, +__mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclass, struct lockdep_map *nest_lock, unsigned long ip, struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx) { @@ -1061,9 +1071,7 @@ acquired: __ww_mutex_check_waiters(lock, ww_ctx); } - mutex_remove_waiter(lock, &waiter, current); - if (likely(list_empty(&lock->wait_list))) - __mutex_clear_flag(lock, MUTEX_FLAGS); + __mutex_remove_waiter(lock, &waiter); debug_mutex_free_waiter(&waiter); @@ -1080,7 +1088,7 @@ skip_wait: err: __set_current_state(TASK_RUNNING); - mutex_remove_waiter(lock, &waiter, current); + __mutex_remove_waiter(lock, &waiter); err_early_kill: spin_unlock(&lock->wait_lock); debug_mutex_free_waiter(&waiter); @@ -1090,14 +1098,14 @@ err_early_kill: } static int __sched -__mutex_lock(struct mutex *lock, long state, unsigned int subclass, +__mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass, struct lockdep_map *nest_lock, unsigned long ip) { return __mutex_lock_common(lock, state, subclass, nest_lock, ip, NULL, false); } static int __sched -__ww_mutex_lock(struct mutex *lock, long state, unsigned int subclass, +__ww_mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass, struct lockdep_map *nest_lock, unsigned long ip, struct ww_acquire_ctx *ww_ctx) { diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h index 1c2287d3fa71..f0c710b1d192 100644 --- a/kernel/locking/mutex.h +++ b/kernel/locking/mutex.h @@ -10,12 +10,10 @@ * !CONFIG_DEBUG_MUTEXES case. Most of them are NOPs: */ -#define mutex_remove_waiter(lock, waiter, task) \ - __list_del((waiter)->list.prev, (waiter)->list.next) - #define debug_mutex_wake_waiter(lock, waiter) do { } while (0) #define debug_mutex_free_waiter(waiter) do { } while (0) #define debug_mutex_add_waiter(lock, waiter, ti) do { } while (0) +#define debug_mutex_remove_waiter(lock, waiter, ti) do { } while (0) #define debug_mutex_unlock(lock) do { } while (0) #define debug_mutex_init(lock, name, key) do { } while (0) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 406818196a9f..b5d9bb5202c6 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1135,7 +1135,7 @@ void __sched rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) * * Must be called with lock->wait_lock held and interrupts disabled */ -static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, int state, +static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state, struct hrtimer_sleeper *timeout, struct rt_mutex_waiter *waiter) { @@ -1190,7 +1190,7 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock, /* * Slow path lock function: */ -static int __sched rt_mutex_slowlock(struct rt_mutex *lock, int state, +static int __sched rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state, struct hrtimer_sleeper *timeout, enum rtmutex_chainwalk chwalk) { diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 809b0016d344..16bfbb10c74d 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -889,7 +889,7 @@ rwsem_spin_on_owner(struct rw_semaphore *sem) * Wait for the read lock to be granted */ static struct rw_semaphore __sched * -rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, int state) +rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, unsigned int state) { long adjustment = -RWSEM_READER_BIAS; long rcnt = (count >> RWSEM_READER_SHIFT); |