diff options
| -rw-r--r-- | kernel/lockdep.c | 170 |
1 files changed, 105 insertions, 65 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 07a3d74a84b..01e75055903 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -43,13 +43,49 @@ #include "lockdep_internals.h" /* - * hash_lock: protects the lockdep hashes and class/list/hash allocators. + * lockdep_lock: protects the lockdep graph, the hashes and the + * class/list/hash allocators. * * This is one of the rare exceptions where it's justified * to use a raw spinlock - we really dont want the spinlock - * code to recurse back into the lockdep code. + * code to recurse back into the lockdep code... */ -static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; +static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; + +static int graph_lock(void) +{ + __raw_spin_lock(&lockdep_lock); + /* + * Make sure that if another CPU detected a bug while + * walking the graph we dont change it (while the other + * CPU is busy printing out stuff with the graph lock + * dropped already) + */ + if (!debug_locks) { + __raw_spin_unlock(&lockdep_lock); + return 0; + } + return 1; +} + +static inline int graph_unlock(void) +{ + __raw_spin_unlock(&lockdep_lock); + return 0; +} + +/* + * Turn lock debugging off and return with 0 if it was off already, + * and also release the graph lock: + */ +static inline int debug_locks_off_graph_unlock(void) +{ + int ret = debug_locks_off(); + + __raw_spin_unlock(&lockdep_lock); + + return ret; +} static int lockdep_initialized; @@ -57,14 +93,15 @@ unsigned long nr_list_entries; static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; /* - * Allocate a lockdep entry. (assumes hash_lock held, returns + * Allocate a lockdep entry. (assumes the graph_lock held, returns * with NULL on failure) */ static struct lock_list *alloc_list_entry(void) { if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { - __raw_spin_unlock(&hash_lock); - debug_locks_off(); + if (!debug_locks_off_graph_unlock()) + return NULL; + printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); printk("turning off the locking correctness validator.\n"); return NULL; @@ -205,7 +242,7 @@ static int softirq_verbose(struct lock_class *class) /* * Stack-trace: tightly packed array of stack backtrace - * addresses. Protected by the hash_lock. + * addresses. Protected by the graph_lock. */ unsigned long nr_stack_trace_entries; static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; @@ -224,18 +261,15 @@ static int save_trace(struct stack_trace *trace) trace->max_entries = trace->nr_entries; nr_stack_trace_entries += trace->nr_entries; - if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) { - __raw_spin_unlock(&hash_lock); - return 0; - } if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) { - __raw_spin_unlock(&hash_lock); - if (debug_locks_off()) { - printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); - printk("turning off the locking correctness validator.\n"); - dump_stack(); - } + if (!debug_locks_off_graph_unlock()) + return 0; + + printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); + printk("turning off the locking correctness validator.\n"); + dump_stack(); + return 0; } @@ -524,9 +558,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth) { struct task_struct *curr = current; - __raw_spin_unlock(&hash_lock); - debug_locks_off(); - if (debug_locks_silent) + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; printk("\n=======================================================\n"); @@ -554,12 +586,10 @@ static noinline int print_circular_bug_tail(void) if (debug_locks_silent) return 0; - /* hash_lock unlocked by the header */ - __raw_spin_lock(&hash_lock); this.class = check_source->class; if (!save_trace(&this.trace)) return 0; - __raw_spin_unlock(&hash_lock); + print_circular_bug_entry(&this, 0); printk("\nother info that might help us debug this:\n\n"); @@ -575,8 +605,10 @@ static noinline int print_circular_bug_tail(void) static int noinline print_infinite_recursion_bug(void) { - __raw_spin_unlock(&hash_lock); - DEBUG_LOCKS_WARN_ON(1); + if (!debug_locks_off_graph_unlock()) + return 0; + + WARN_ON(1); return 0; } @@ -711,9 +743,7 @@ print_bad_irq_dependency(struct task_struct *curr, enum lock_usage_bit bit2, const char *irqclass) { - __raw_spin_unlock(&hash_lock); - debug_locks_off(); - if (debug_locks_silent) + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; printk("\n======================================================\n"); @@ -794,9 +824,7 @@ static int print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, struct held_lock *next) { - debug_locks_off(); - __raw_spin_unlock(&hash_lock); - if (debug_locks_silent) + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; printk("\n=============================================\n"); @@ -972,14 +1000,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, * Debugging printouts: */ if (verbose(prev->class) || verbose(next->class)) { - __raw_spin_unlock(&hash_lock); + graph_unlock(); printk("\n new dependency: "); print_lock_name(prev->class); printk(" => "); print_lock_name(next->class); printk("\n"); dump_stack(); - __raw_spin_lock(&hash_lock); + return graph_lock(); } return 1; } @@ -1044,8 +1072,10 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next) } return 1; out_bug: - __raw_spin_unlock(&hash_lock); - DEBUG_LOCKS_WARN_ON(1); + if (!debug_locks_off_graph_unlock()) + return 0; + + WARN_ON(1); return 0; } @@ -1199,7 +1229,10 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) hash_head = classhashentry(key); raw_local_irq_save(flags); - __raw_spin_lock(&hash_lock); + if (!graph_lock()) { + raw_local_irq_restore(flags); + return NULL; + } /* * We have to do the hash-walk again, to avoid races * with another CPU: @@ -1212,9 +1245,12 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) * the hash: */ if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { - __raw_spin_unlock(&hash_lock); + if (!debug_locks_off_graph_unlock()) { + raw_local_irq_restore(flags); + return NULL; + } raw_local_irq_restore(flags); - debug_locks_off(); + printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); printk("turning off the locking correctness validator.\n"); return NULL; @@ -1235,18 +1271,23 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) list_add_tail_rcu(&class->hash_entry, hash_head); if (verbose(class)) { - __raw_spin_unlock(&hash_lock); + graph_unlock(); raw_local_irq_restore(flags); + printk("\nnew class %p: %s", class->key, class->name); if (class->name_version > 1) printk("#%d", class->name_version); printk("\n"); dump_stack(); + raw_local_irq_save(flags); - __raw_spin_lock(&hash_lock); + if (!graph_lock()) { + raw_local_irq_restore(flags); + return NULL; + } } out_unlock_set: - __raw_spin_unlock(&hash_lock); + graph_unlock(); raw_local_irq_restore(flags); if (!subclass || force) @@ -1287,19 +1328,21 @@ cache_hit: * Allocate a new chain entry from the static array, and add * it to the hash: */ - __raw_spin_lock(&hash_lock); + if (!graph_lock()) + return 0; /* * We have to walk the chain again locked - to avoid duplicates: */ list_for_each_entry(chain, hash_head, entry) { if (chain->chain_key == chain_key) { - __raw_spin_unlock(&hash_lock); + graph_unlock(); goto cache_hit; } } if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { - __raw_spin_unlock(&hash_lock); - debug_locks_off(); + if (!debug_locks_off_graph_unlock()) + return 0; + printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); printk("turning off the locking correctness validator.\n"); return 0; @@ -1375,9 +1418,7 @@ print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other, struct held_lock *this, int forwards, const char *irqclass) { - __raw_spin_unlock(&hash_lock); - debug_locks_off(); - if (debug_locks_silent) + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; printk("\n=========================================================\n"); @@ -1466,9 +1507,7 @@ static int print_usage_bug(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) { - __raw_spin_unlock(&hash_lock); - debug_locks_off(); - if (debug_locks_silent) + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; printk("\n=================================\n"); @@ -1529,12 +1568,13 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, if (likely(this->class->usage_mask & new_mask)) return 1; - __raw_spin_lock(&hash_lock); + if (!graph_lock()) + return 0; /* * Make sure we didnt race: */ if (unlikely(this->class->usage_mask & new_mask)) { - __raw_spin_unlock(&hash_lock); + graph_unlock(); return 1; } @@ -1720,16 +1760,16 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, debug_atomic_dec(&nr_unused_locks); break; default: - __raw_spin_unlock(&hash_lock); - debug_locks_off(); + if (!debug_locks_off_graph_unlock()) + return 0; WARN_ON(1); return 0; } - __raw_spin_unlock(&hash_lock); + graph_unlock(); /* - * We must printk outside of the hash_lock: + * We must printk outside of the graph_lock: */ if (ret == 2) { printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); @@ -2127,7 +2167,7 @@ out_calc_hash: * We look up the chain_key and do the O(N^2) check and update of * the dependencies only if this is a new dependency chain. * (If lookup_chain_cache() returns with 1 it acquires - * hash_lock for us) + * graph_lock for us) */ if (!trylock && (check == 2) && lookup_chain_cache(chain_key, class)) { /* @@ -2160,7 +2200,7 @@ out_calc_hash: if (!chain_head && ret != 2) if (!check_prevs_add(curr, hlock)) return 0; - __raw_spin_unlock(&hash_lock); + graph_unlock(); } curr->lockdep_depth++; check_chain_key(curr); @@ -2472,7 +2512,7 @@ void lockdep_free_key_range(void *start, unsigned long size) int i; raw_local_irq_save(flags); - __raw_spin_lock(&hash_lock); + graph_lock(); /* * Unhash all classes that were created by this module: @@ -2486,7 +2526,7 @@ void lockdep_free_key_range(void *start, unsigned long size) zap_class(class); } - __raw_spin_unlock(&hash_lock); + graph_unlock(); raw_local_irq_restore(flags); } @@ -2514,20 +2554,20 @@ void lockdep_reset_lock(struct lockdep_map *lock) * Debug check: in the end all mapped classes should * be gone. */ - __raw_spin_lock(&hash_lock); + graph_lock(); for (i = 0; i < CLASSHASH_SIZE; i++) { head = classhash_table + i; if (list_empty(head)) continue; list_for_each_entry_safe(class, next, head, hash_entry) { if (unlikely(class == lock->class_cache)) { - __raw_spin_unlock(&hash_lock); - DEBUG_LOCKS_WARN_ON(1); + if (debug_locks_off_graph_unlock()) + WARN_ON(1); goto out_restore; } } } - __raw_spin_unlock(&hash_lock); + graph_unlock(); out_restore: raw_local_irq_restore(flags); |