diff options
Diffstat (limited to 'kernel/lockdep.c')
| -rw-r--r-- | kernel/lockdep.c | 3244 |
1 files changed, 0 insertions, 3244 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c deleted file mode 100644 index 81a4e4a3f08..00000000000 --- a/kernel/lockdep.c +++ /dev/null @@ -1,3244 +0,0 @@ -/* - * kernel/lockdep.c - * - * Runtime locking correctness validator - * - * Started by Ingo Molnar: - * - * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> - * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> - * - * this code maps all the lock dependencies as they occur in a live kernel - * and will warn about the following classes of locking bugs: - * - * - lock inversion scenarios - * - circular lock dependencies - * - hardirq/softirq safe/unsafe locking bugs - * - * Bugs are reported even if the current locking scenario does not cause - * any deadlock at this point. - * - * I.e. if anytime in the past two locks were taken in a different order, - * even if it happened for another task, even if those were different - * locks (but of the same class as this lock), this code will detect it. - * - * Thanks to Arjan van de Ven for coming up with the initial idea of - * mapping lock dependencies runtime. - */ -#include <linux/mutex.h> -#include <linux/sched.h> -#include <linux/delay.h> -#include <linux/module.h> -#include <linux/proc_fs.h> -#include <linux/seq_file.h> -#include <linux/spinlock.h> -#include <linux/kallsyms.h> -#include <linux/interrupt.h> -#include <linux/stacktrace.h> -#include <linux/debug_locks.h> -#include <linux/irqflags.h> -#include <linux/utsname.h> -#include <linux/hash.h> - -#include <asm/sections.h> - -#include "lockdep_internals.h" - -#ifdef CONFIG_PROVE_LOCKING -int prove_locking = 1; -module_param(prove_locking, int, 0644); -#else -#define prove_locking 0 -#endif - -#ifdef CONFIG_LOCK_STAT -int lock_stat = 1; -module_param(lock_stat, int, 0644); -#else -#define lock_stat 0 -#endif - -/* - * 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... - */ -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) -{ - if (debug_locks && !__raw_spin_is_locked(&lockdep_lock)) - return DEBUG_LOCKS_WARN_ON(1); - - __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; - -unsigned long nr_list_entries; -static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; - -/* - * All data structures here are protected by the global debug_lock. - * - * Mutex key structs only get allocated, once during bootup, and never - * get freed - this significantly simplifies the debugging code. - */ -unsigned long nr_lock_classes; -static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; - -#ifdef CONFIG_LOCK_STAT -static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats); - -static int lock_contention_point(struct lock_class *class, unsigned long ip) -{ - int i; - - for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) { - if (class->contention_point[i] == 0) { - class->contention_point[i] = ip; - break; - } - if (class->contention_point[i] == ip) - break; - } - - return i; -} - -static void lock_time_inc(struct lock_time *lt, s64 time) -{ - if (time > lt->max) - lt->max = time; - - if (time < lt->min || !lt->min) - lt->min = time; - - lt->total += time; - lt->nr++; -} - -static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) -{ - dst->min += src->min; - dst->max += src->max; - dst->total += src->total; - dst->nr += src->nr; -} - -struct lock_class_stats lock_stats(struct lock_class *class) -{ - struct lock_class_stats stats; - int cpu, i; - - memset(&stats, 0, sizeof(struct lock_class_stats)); - for_each_possible_cpu(cpu) { - struct lock_class_stats *pcs = - &per_cpu(lock_stats, cpu)[class - lock_classes]; - - for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) - stats.contention_point[i] += pcs->contention_point[i]; - - lock_time_add(&pcs->read_waittime, &stats.read_waittime); - lock_time_add(&pcs->write_waittime, &stats.write_waittime); - - lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); - lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); - - for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) - stats.bounces[i] += pcs->bounces[i]; - } - - return stats; -} - -void clear_lock_stats(struct lock_class *class) -{ - int cpu; - - for_each_possible_cpu(cpu) { - struct lock_class_stats *cpu_stats = - &per_cpu(lock_stats, cpu)[class - lock_classes]; - - memset(cpu_stats, 0, sizeof(struct lock_class_stats)); - } - memset(class->contention_point, 0, sizeof(class->contention_point)); -} - -static struct lock_class_stats *get_lock_stats(struct lock_class *class) -{ - return &get_cpu_var(lock_stats)[class - lock_classes]; -} - -static void put_lock_stats(struct lock_class_stats *stats) -{ - put_cpu_var(lock_stats); -} - -static void lock_release_holdtime(struct held_lock *hlock) -{ - struct lock_class_stats *stats; - s64 holdtime; - - if (!lock_stat) - return; - - holdtime = sched_clock() - hlock->holdtime_stamp; - - stats = get_lock_stats(hlock->class); - if (hlock->read) - lock_time_inc(&stats->read_holdtime, holdtime); - else - lock_time_inc(&stats->write_holdtime, holdtime); - put_lock_stats(stats); -} -#else -static inline void lock_release_holdtime(struct held_lock *hlock) -{ -} -#endif - -/* - * We keep a global list of all lock classes. The list only grows, - * never shrinks. The list is only accessed with the lockdep - * spinlock lock held. - */ -LIST_HEAD(all_lock_classes); - -/* - * The lockdep classes are in a hash-table as well, for fast lookup: - */ -#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) -#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) -#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) -#define classhashentry(key) (classhash_table + __classhashfn((key))) - -static struct list_head classhash_table[CLASSHASH_SIZE]; - -/* - * We put the lock dependency chains into a hash-table as well, to cache - * their existence: - */ -#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) -#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) -#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) -#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) - -static struct list_head chainhash_table[CHAINHASH_SIZE]; - -/* - * The hash key of the lock dependency chains is a hash itself too: - * it's a hash of all locks taken up to that lock, including that lock. - * It's a 64-bit hash, because it's important for the keys to be - * unique. - */ -#define iterate_chain_key(key1, key2) \ - (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ - ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ - (key2)) - -void lockdep_off(void) -{ - current->lockdep_recursion++; -} - -EXPORT_SYMBOL(lockdep_off); - -void lockdep_on(void) -{ - current->lockdep_recursion--; -} - -EXPORT_SYMBOL(lockdep_on); - -/* - * Debugging switches: - */ - -#define VERBOSE 0 -#define VERY_VERBOSE 0 - -#if VERBOSE -# define HARDIRQ_VERBOSE 1 -# define SOFTIRQ_VERBOSE 1 -#else -# define HARDIRQ_VERBOSE 0 -# define SOFTIRQ_VERBOSE 0 -#endif - -#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE -/* - * Quick filtering for interesting events: - */ -static int class_filter(struct lock_class *class) -{ -#if 0 - /* Example */ - if (class->name_version == 1 && - !strcmp(class->name, "lockname")) - return 1; - if (class->name_version == 1 && - !strcmp(class->name, "&struct->lockfield")) - return 1; -#endif - /* Filter everything else. 1 would be to allow everything else */ - return 0; -} -#endif - -static int verbose(struct lock_class *class) -{ -#if VERBOSE - return class_filter(class); -#endif - return 0; -} - -/* - * Stack-trace: tightly packed array of stack backtrace - * addresses. Protected by the graph_lock. - */ -unsigned long nr_stack_trace_entries; -static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; - -static int save_trace(struct stack_trace *trace) -{ - trace->nr_entries = 0; - trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; - trace->entries = stack_trace + nr_stack_trace_entries; - - trace->skip = 3; - - save_stack_trace(trace); - - trace->max_entries = trace->nr_entries; - - nr_stack_trace_entries += trace->nr_entries; - - if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) { - 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; - } - - return 1; -} - -unsigned int nr_hardirq_chains; -unsigned int nr_softirq_chains; -unsigned int nr_process_chains; -unsigned int max_lockdep_depth; -unsigned int max_recursion_depth; - -#ifdef CONFIG_DEBUG_LOCKDEP -/* - * We cannot printk in early bootup code. Not even early_printk() - * might work. So we mark any initialization errors and printk - * about it later on, in lockdep_info(). - */ -static int lockdep_init_error; -static unsigned long lockdep_init_trace_data[20]; -static struct stack_trace lockdep_init_trace = { - .max_entries = ARRAY_SIZE(lockdep_init_trace_data), - .entries = lockdep_init_trace_data, -}; - -/* - * Various lockdep statistics: - */ -atomic_t chain_lookup_hits; -atomic_t chain_lookup_misses; -atomic_t hardirqs_on_events; -atomic_t hardirqs_off_events; -atomic_t redundant_hardirqs_on; -atomic_t redundant_hardirqs_off; -atomic_t softirqs_on_events; -atomic_t softirqs_off_events; -atomic_t redundant_softirqs_on; -atomic_t redundant_softirqs_off; -atomic_t nr_unused_locks; -atomic_t nr_cyclic_checks; -atomic_t nr_cyclic_check_recursions; -atomic_t nr_find_usage_forwards_checks; -atomic_t nr_find_usage_forwards_recursions; -atomic_t nr_find_usage_backwards_checks; -atomic_t nr_find_usage_backwards_recursions; -# define debug_atomic_inc(ptr) atomic_inc(ptr) -# define debug_atomic_dec(ptr) atomic_dec(ptr) -# define debug_atomic_read(ptr) atomic_read(ptr) -#else -# define debug_atomic_inc(ptr) do { } while (0) -# define debug_atomic_dec(ptr) do { } while (0) -# define debug_atomic_read(ptr) 0 -#endif - -/* - * Locking printouts: - */ - -static const char *usage_str[] = -{ - [LOCK_USED] = "initial-use ", - [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W", - [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W", - [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W", - [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W", - [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R", - [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R", - [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R", - [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R", -}; - -const char * __get_key_name(struct lockdep_subclass_key *key, char *str) -{ - return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); -} - -void -get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4) -{ - *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.'; - - if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) - *c1 = '+'; - else - if (class->usage_mask & LOCKF_ENABLED_HARDIRQS) - *c1 = '-'; - - if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) - *c2 = '+'; - else - if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS) - *c2 = '-'; - - if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) - *c3 = '-'; - if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) { - *c3 = '+'; - if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) - *c3 = '?'; - } - - if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) - *c4 = '-'; - if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) { - *c4 = '+'; - if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) - *c4 = '?'; - } -} - -static void print_lock_name(struct lock_class *class) -{ - char str[KSYM_NAME_LEN], c1, c2, c3, c4; - const char *name; - - get_usage_chars(class, &c1, &c2, &c3, &c4); - - name = class->name; - if (!name) { - name = __get_key_name(class->key, str); - printk(" (%s", name); - } else { - printk(" (%s", name); - if (class->name_version > 1) - printk("#%d", class->name_version); - if (class->subclass) - printk("/%d", class->subclass); - } - printk("){%c%c%c%c}", c1, c2, c3, c4); -} - -static void print_lockdep_cache(struct lockdep_map *lock) -{ - const char *name; - char str[KSYM_NAME_LEN]; - - name = lock->name; - if (!name) - name = __get_key_name(lock->key->subkeys, str); - - printk("%s", name); -} - -static void print_lock(struct held_lock *hlock) -{ - print_lock_name(hlock->class); - printk(", at: "); - print_ip_sym(hlock->acquire_ip); -} - -static void lockdep_print_held_locks(struct task_struct *curr) -{ - int i, depth = curr->lockdep_depth; - - if (!depth) { - printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); - return; - } - printk("%d lock%s held by %s/%d:\n", - depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); - - for (i = 0; i < depth; i++) { - printk(" #%d: ", i); - print_lock(curr->held_locks + i); - } -} - -static void print_lock_class_header(struct lock_class *class, int depth) -{ - int bit; - - printk("%*s->", depth, ""); - print_lock_name(class); - printk(" ops: %lu", class->ops); - printk(" {\n"); - - for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { - if (class->usage_mask & (1 << bit)) { - int len = depth; - - len += printk("%*s %s", depth, "", usage_str[bit]); - len += printk(" at:\n"); - print_stack_trace(class->usage_traces + bit, len); - } - } - printk("%*s }\n", depth, ""); - - printk("%*s ... key at: ",depth,""); - print_ip_sym((unsigned long)class->key); -} - -/* - * printk all lock dependencies starting at <entry>: - */ -static void print_lock_dependencies(struct lock_class *class, int depth) -{ - struct lock_list *entry; - - if (DEBUG_LOCKS_WARN_ON(depth >= 20)) - return; - - print_lock_class_header(class, depth); - - list_for_each_entry(entry, &class->locks_after, entry) { - if (DEBUG_LOCKS_WARN_ON(!entry->class)) - return; - - print_lock_dependencies(entry->class, depth + 1); - - printk("%*s ... acquired at:\n",depth,""); - print_stack_trace(&entry->trace, 2); - printk("\n"); - } -} - -static void print_kernel_version(void) -{ - printk("%s %.*s\n", init_utsname()->release, - (int)strcspn(init_utsname()->version, " "), - init_utsname()->version); -} - -static int very_verbose(struct lock_class *class) -{ -#if VERY_VERBOSE - return class_filter(class); -#endif - return 0; -} - -/* - * Is this the address of a static object: - */ -static int static_obj(void *obj) -{ - unsigned long start = (unsigned long) &_stext, - end = (unsigned long) &_end, - addr = (unsigned long) obj; -#ifdef CONFIG_SMP - int i; -#endif - - /* - * static variable? - */ - if ((addr >= start) && (addr < end)) - return 1; - -#ifdef CONFIG_SMP - /* - * percpu var? - */ - for_each_possible_cpu(i) { - start = (unsigned long) &__per_cpu_start + per_cpu_offset(i); - end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM - + per_cpu_offset(i); - - if ((addr >= start) && (addr < end)) - return 1; - } -#endif - - /* - * module var? - */ - return is_module_address(addr); -} - -/* - * To make lock name printouts unique, we calculate a unique - * class->name_version generation counter: - */ -static int count_matching_names(struct lock_class *new_class) -{ - struct lock_class *class; - int count = 0; - - if (!new_class->name) - return 0; - - list_for_each_entry(class, &all_lock_classes, lock_entry) { - if (new_class->key - new_class->subclass == class->key) - return class->name_version; - if (class->name && !strcmp(class->name, new_class->name)) - count = max(count, class->name_version); - } - - return count + 1; -} - -/* - * Register a lock's class in the hash-table, if the class is not present - * yet. Otherwise we look it up. We cache the result in the lock object - * itself, so actual lookup of the hash should be once per lock object. - */ -static inline struct lock_class * -look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) -{ - struct lockdep_subclass_key *key; - struct list_head *hash_head; - struct lock_class *class; - -#ifdef CONFIG_DEBUG_LOCKDEP - /* - * If the architecture calls into lockdep before initializing - * the hashes then we'll warn about it later. (we cannot printk - * right now) - */ - if (unlikely(!lockdep_initialized)) { - lockdep_init(); - lockdep_init_error = 1; - save_stack_trace(&lockdep_init_trace); - } -#endif - - /* - * Static locks do not have their class-keys yet - for them the key - * is the lock object itself: - */ - if (unlikely(!lock->key)) - lock->key = (void *)lock; - - /* - * NOTE: the class-key must be unique. For dynamic locks, a static - * lock_class_key variable is passed in through the mutex_init() - * (or spin_lock_init()) call - which acts as the key. For static - * locks we use the lock object itself as the key. - */ - BUILD_BUG_ON(sizeof(struct lock_class_key) > - sizeof(struct lockdep_map)); - - key = lock->key->subkeys + subclass; - - hash_head = classhashentry(key); - - /* - * We can walk the hash lockfree, because the hash only - * grows, and we are careful when adding entries to the end: - */ - list_for_each_entry(class, hash_head, hash_entry) { - if (class->key == key) { - WARN_ON_ONCE(class->name != lock->name); - return class; - } - } - - return NULL; -} - -/* - * Register a lock's class in the hash-table, if the class is not present - * yet. Otherwise we look it up. We cache the result in the lock object - * itself, so actual lookup of the hash should be once per lock object. - */ -static inline struct lock_class * -register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) -{ - struct lockdep_subclass_key *key; - struct list_head *hash_head; - struct lock_class *class; - unsigned long flags; - - class = look_up_lock_class(lock, subclass); - if (likely(class)) - return class; - - /* - * Debug-check: all keys must be persistent! - */ - if (!static_obj(lock->key)) { - debug_locks_off(); - printk("INFO: trying to register non-static key.\n"); - printk("the code is fine but needs lockdep annotation.\n"); - printk("turning off the locking correctness validator.\n"); - dump_stack(); - - return NULL; - } - - key = lock->key->subkeys + subclass; - hash_head = classhashentry(key); - - raw_local_irq_save(flags); - if (!graph_lock()) { - raw_local_irq_restore(flags); - return NULL; - } - /* - * We have to do the hash-walk again, to avoid races - * with another CPU: - */ - list_for_each_entry(class, hash_head, hash_entry) - if (class->key == key) - goto out_unlock_set; - /* - * Allocate a new key from the static array, and add it to - * the hash: - */ - if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { - if (!debug_locks_off_graph_unlock()) { - raw_local_irq_restore(flags); - return NULL; - } - raw_local_irq_restore(flags); - - printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); - printk("turning off the locking correctness validator.\n"); - return NULL; - } - class = lock_classes + nr_lock_classes++; - debug_atomic_inc(&nr_unused_locks); - class->key = key; - class->name = lock->name; - class->subclass = subclass; - INIT_LIST_HEAD(&class->lock_entry); - INIT_LIST_HEAD(&class->locks_before); - INIT_LIST_HEAD(&class->locks_after); - class->name_version = count_matching_names(class); - /* - * We use RCU's safe list-add method to make - * parallel walking of the hash-list safe: - */ - list_add_tail_rcu(&class->hash_entry, hash_head); - /* - * Add it to the global list of classes: - */ - list_add_tail_rcu(&class->lock_entry, &all_lock_classes); - - if (verbose(class)) { - 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); - if (!graph_lock()) { - raw_local_irq_restore(flags); - return NULL; - } - } -out_unlock_set: - graph_unlock(); - raw_local_irq_restore(flags); - - if (!subclass || force) - lock->class_cache = class; - - if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) - return NULL; - - return class; -} - -#ifdef CONFIG_PROVE_LOCKING -/* - * 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) { - 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; - } - return list_entries + nr_list_entries++; -} - -/* - * Add a new dependency to the head of the list: - */ -static int add_lock_to_list(struct lock_class *class, struct lock_class *this, - struct list_head *head, unsigned long ip, int distance) -{ - struct lock_list *entry; - /* - * Lock not present yet - get a new dependency struct and - * add it to the list: - */ - entry = alloc_list_entry(); - if (!entry) - return 0; - - entry->class = this; - entry->distance = distance; - if (!save_trace(&entry->trace)) - return 0; - - /* - * Since we never remove from the dependency list, the list can - * be walked lockless by other CPUs, it's only allocation - * that must be protected by the spinlock. But this also means - * we must make new entries visible only once writes to the - * entry become visible - hence the RCU op: - */ - list_add_tail_rcu(&entry->entry, head); - - return 1; -} - -/* - * Recursive, forwards-direction lock-dependency checking, used for - * both noncyclic checking and for hardirq-unsafe/softirq-unsafe - * checking. - * - * (to keep the stackframe of the recursive functions small we - * use these global variables, and we also mark various helper - * functions as noinline.) - */ -static struct held_lock *check_source, *check_target; - -/* - * Print a dependency chain entry (this is only done when a deadlock - * has been detected): - */ -static noinline int -print_circular_bug_entry(struct lock_list *target, unsigned int depth) -{ - if (debug_locks_silent) - return 0; - printk("\n-> #%u", depth); - print_lock_name(target->class); - printk(":\n"); - print_stack_trace(&target->trace, 6); - - return 0; -} - -/* - * When a circular dependency is detected, print the - * header first: - */ -static noinline int -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) - return 0; - - printk("\n=======================================================\n"); - printk( "[ INFO: possible circular locking dependency detected ]\n"); - print_kernel_version(); - printk( "-------------------------------------------------------\n"); - printk("%s/%d is trying to acquire lock:\n", - curr->comm, task_pid_nr(curr)); - print_lock(check_source); - printk("\nbut task is already holding lock:\n"); - print_lock(check_target); - printk("\nwhich lock already depends on the new lock.\n\n"); - printk("\nthe existing dependency chain (in reverse order) is:\n"); - - print_circular_bug_entry(entry, depth); - - return 0; -} - -static noinline int print_circular_bug_tail(void) -{ - struct task_struct *curr = current; - struct lock_list this; - - if (debug_locks_silent) - return 0; - - this.class = check_source->class; - if (!save_trace(&this.trace)) - return 0; - - print_circular_bug_entry(&this, 0); - - printk("\nother info that might help us debug this:\n\n"); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -#define RECURSION_LIMIT 40 - -static int noinline print_infinite_recursion_bug(void) -{ - if (!debug_locks_off_graph_unlock()) - return 0; - - WARN_ON(1); - - return 0; -} - -/* - * Prove that the dependency graph starting at <entry> can not - * lead to <target>. Print an error and return 0 if it does. - */ -static noinline int -check_noncircular(struct lock_class *source, unsigned int depth) -{ - struct lock_list *entry; - - debug_atomic_inc(&nr_cyclic_check_recursions); - if (depth > max_recursion_depth) - max_recursion_depth = depth; - if (depth >= RECURSION_LIMIT) - return print_infinite_recursion_bug(); - /* - * Check this lock's dependency list: - */ - list_for_each_entry(entry, &source->locks_after, entry) { - if (entry->class == check_target->class) - return print_circular_bug_header(entry, depth+1); - debug_atomic_inc(&nr_cyclic_checks); - if (!check_noncircular(entry->class, depth+1)) - return print_circular_bug_entry(entry, depth+1); - } - return 1; -} - -#ifdef CONFIG_TRACE_IRQFLAGS -/* - * Forwards and backwards subgraph searching, for the purposes of - * proving that two subgraphs can be connected by a new dependency - * without creating any illegal irq-safe -> irq-unsafe lock dependency. - */ -static enum lock_usage_bit find_usage_bit; -static struct lock_class *forwards_match, *backwards_match; - -/* - * Find a node in the forwards-direction dependency sub-graph starting - * at <source> that matches <find_usage_bit>. - * - * Return 2 if such a node exists in the subgraph, and put that node - * into <forwards_match>. - * - * Return 1 otherwise and keep <forwards_match> unchanged. - * Return 0 on error. - */ -static noinline int -find_usage_forwards(struct lock_class *source, unsigned int depth) -{ - struct lock_list *entry; - int ret; - - if (depth > max_recursion_depth) - max_recursion_depth = depth; - if (depth >= RECURSION_LIMIT) - return print_infinite_recursion_bug(); - - debug_atomic_inc(&nr_find_usage_forwards_checks); - if (source->usage_mask & (1 << find_usage_bit)) { - forwards_match = source; - return 2; - } - - /* - * Check this lock's dependency list: - */ - list_for_each_entry(entry, &source->locks_after, entry) { - debug_atomic_inc(&nr_find_usage_forwards_recursions); - ret = find_usage_forwards(entry->class, depth+1); - if (ret == 2 || ret == 0) - return ret; - } - return 1; -} - -/* - * Find a node in the backwards-direction dependency sub-graph starting - * at <source> that matches <find_usage_bit>. - * - * Return 2 if such a node exists in the subgraph, and put that node - * into <backwards_match>. - * - * Return 1 otherwise and keep <backwards_match> unchanged. - * Return 0 on error. - */ -static noinline int -find_usage_backwards(struct lock_class *source, unsigned int depth) -{ - struct lock_list *entry; - int ret; - - if (!__raw_spin_is_locked(&lockdep_lock)) - return DEBUG_LOCKS_WARN_ON(1); - - if (depth > max_recursion_depth) - max_recursion_depth = depth; - if (depth >= RECURSION_LIMIT) - return print_infinite_recursion_bug(); - - debug_atomic_inc(&nr_find_usage_backwards_checks); - if (source->usage_mask & (1 << find_usage_bit)) { - backwards_match = source; - return 2; - } - - /* - * Check this lock's dependency list: - */ - list_for_each_entry(entry, &source->locks_before, entry) { - debug_atomic_inc(&nr_find_usage_backwards_recursions); - ret = find_usage_backwards(entry->class, depth+1); - if (ret == 2 || ret == 0) - return ret; - } - return 1; -} - -static int -print_bad_irq_dependency(struct task_struct *curr, - struct held_lock *prev, - struct held_lock *next, - enum lock_usage_bit bit1, - enum lock_usage_bit bit2, - const char *irqclass) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return 0; - - printk("\n======================================================\n"); - printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", - irqclass, irqclass); - print_kernel_version(); - printk( "------------------------------------------------------\n"); - printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", - curr->comm, task_pid_nr(curr), - curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, - curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, - curr->hardirqs_enabled, - curr->softirqs_enabled); - print_lock(next); - - printk("\nand this task is already holding:\n"); - print_lock(prev); - printk("which would create a new lock dependency:\n"); - print_lock_name(prev->class); - printk(" ->"); - print_lock_name(next->class); - printk("\n"); - - printk("\nbut this new dependency connects a %s-irq-safe lock:\n", - irqclass); - print_lock_name(backwards_match); - printk("\n... which became %s-irq-safe at:\n", irqclass); - - print_stack_trace(backwards_match->usage_traces + bit1, 1); - - printk("\nto a %s-irq-unsafe lock:\n", irqclass); - print_lock_name(forwards_match); - printk("\n... which became %s-irq-unsafe at:\n", irqclass); - printk("..."); - - print_stack_trace(forwards_match->usage_traces + bit2, 1); - - printk("\nother info that might help us debug this:\n\n"); - lockdep_print_held_locks(curr); - - printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass); - print_lock_dependencies(backwards_match, 0); - - printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass); - print_lock_dependencies(forwards_match, 0); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -static int -check_usage(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, enum lock_usage_bit bit_backwards, - enum lock_usage_bit bit_forwards, const char *irqclass) -{ - int ret; - - find_usage_bit = bit_backwards; - /* fills in <backwards_match> */ - ret = find_usage_backwards(prev->class, 0); - if (!ret || ret == 1) - return ret; - - find_usage_bit = bit_forwards; - ret = find_usage_forwards(next->class, 0); - if (!ret || ret == 1) - return ret; - /* ret == 2 */ - return print_bad_irq_dependency(curr, prev, next, - bit_backwards, bit_forwards, irqclass); -} - -static int -check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) -{ - /* - * Prove that the new dependency does not connect a hardirq-safe - * lock with a hardirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at <prev>, and the - * forwards-subgraph starting at <next>: - */ - if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ, - LOCK_ENABLED_HARDIRQS, "hard")) - return 0; - - /* - * Prove that the new dependency does not connect a hardirq-safe-read - * lock with a hardirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at <prev>, and the - * forwards-subgraph starting at <next>: - */ - if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ, - LOCK_ENABLED_HARDIRQS, "hard-read")) - return 0; - - /* - * Prove that the new dependency does not connect a softirq-safe - * lock with a softirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at <prev>, and the - * forwards-subgraph starting at <next>: - */ - if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ, - LOCK_ENABLED_SOFTIRQS, "soft")) - return 0; - /* - * Prove that the new dependency does not connect a softirq-safe-read - * lock with a softirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at <prev>, and the - * forwards-subgraph starting at <next>: - */ - if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ, - LOCK_ENABLED_SOFTIRQS, "soft")) - return 0; - - return 1; -} - -static void inc_chains(void) -{ - if (current->hardirq_context) - nr_hardirq_chains++; - else { - if (current->softirq_context) - nr_softirq_chains++; - else - nr_process_chains++; - } -} - -#else - -static inline int -check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) -{ - return 1; -} - -static inline void inc_chains(void) -{ - nr_process_chains++; -} - -#endif - -static int -print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return 0; - - printk("\n=============================================\n"); - printk( "[ INFO: possible recursive locking detected ]\n"); - print_kernel_version(); - printk( "---------------------------------------------\n"); - printk("%s/%d is trying to acquire lock:\n", - curr->comm, task_pid_nr(curr)); - print_lock(next); - printk("\nbut task is already holding lock:\n"); - print_lock(prev); - - printk("\nother info that might help us debug this:\n"); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -/* - * Check whether we are holding such a class already. - * - * (Note that this has to be done separately, because the graph cannot - * detect such classes of deadlocks.) - * - * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read - */ -static int -check_deadlock(struct task_struct *curr, struct held_lock *next, - struct lockdep_map *next_instance, int read) -{ - struct held_lock *prev; - int i; - - for (i = 0; i < curr->lockdep_depth; i++) { - prev = curr->held_locks + i; - if (prev->class != next->class) - continue; - /* - * Allow read-after-read recursion of the same - * lock class (i.e. read_lock(lock)+read_lock(lock)): - */ - if ((read == 2) && prev->read) - return 2; - return print_deadlock_bug(curr, prev, next); - } - return 1; -} - -/* - * There was a chain-cache miss, and we are about to add a new dependency - * to a previous lock. We recursively validate the following rules: - * - * - would the adding of the <prev> -> <next> dependency create a - * circular dependency in the graph? [== circular deadlock] - * - * - does the new prev->next dependency connect any hardirq-safe lock - * (in the full backwards-subgraph starting at <prev>) with any - * hardirq-unsafe lock (in the full forwards-subgraph starting at - * <next>)? [== illegal lock inversion with hardirq contexts] - * - * - does the new prev->next dependency connect any softirq-safe lock - * (in the full backwards-subgraph starting at <prev>) with any - * softirq-unsafe lock (in the full forwards-subgraph starting at - * <next>)? [== illegal lock inversion with softirq contexts] - * - * any of these scenarios could lead to a deadlock. - * - * Then if all the validations pass, we add the forwards and backwards - * dependency. - */ -static int -check_prev_add(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, int distance) -{ - struct lock_list *entry; - int ret; - - /* - * Prove that the new <prev> -> <next> dependency would not - * create a circular dependency in the graph. (We do this by - * forward-recursing into the graph starting at <next>, and - * checking whether we can reach <prev>.) - * - * We are using global variables to control the recursion, to - * keep the stackframe size of the recursive functions low: - */ - check_source = next; - check_target = prev; - if (!(check_noncircular(next->class, 0))) - return print_circular_bug_tail(); - - if (!check_prev_add_irq(curr, prev, next)) - return 0; - - /* - * For recursive read-locks we do all the dependency checks, - * but we dont store read-triggered dependencies (only - * write-triggered dependencies). This ensures that only the - * write-side dependencies matter, and that if for example a - * write-lock never takes any other locks, then the reads are - * equivalent to a NOP. - */ - if (next->read == 2 || prev->read == 2) - return 1; - /* - * Is the <prev> -> <next> dependency already present? - * - * (this may occur even though this is a new chain: consider - * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 - * chains - the second one will be new, but L1 already has - * L2 added to its dependency list, due to the first chain.) - */ - list_for_each_entry(entry, &prev->class->locks_after, entry) { - if (entry->class == next->class) { - if (distance == 1) - entry->distance = 1; - return 2; - } - } - - /* - * Ok, all validations passed, add the new lock - * to the previous lock's dependency list: - */ - ret = add_lock_to_list(prev->class, next->class, - &prev->class->locks_after, next->acquire_ip, distance); - - if (!ret) - return 0; - - ret = add_lock_to_list(next->class, prev->class, - &next->class->locks_before, next->acquire_ip, distance); - if (!ret) - return 0; - - /* - * Debugging printouts: - */ - if (verbose(prev->class) || verbose(next->class)) { - graph_unlock(); - printk("\n new dependency: "); - print_lock_name(prev->class); - printk(" => "); - print_lock_name(next->class); - printk("\n"); - dump_stack(); - return graph_lock(); - } - return 1; -} - -/* - * Add the dependency to all directly-previous locks that are 'relevant'. - * The ones that are relevant are (in increasing distance from curr): - * all consecutive trylock entries and the final non-trylock entry - or - * the end of this context's lock-chain - whichever comes first. - */ -static int -check_prevs_add(struct task_struct *curr, struct held_lock *next) -{ - int depth = curr->lockdep_depth; - struct held_lock *hlock; - - /* - * Debugging checks. - * - * Depth must not be zero for a non-head lock: - */ - if (!depth) - goto out_bug; - /* - * At least two relevant locks must exist for this - * to be a head: - */ - if (curr->held_locks[depth].irq_context != - curr->held_locks[depth-1].irq_context) - goto out_bug; - - for (;;) { - int distance = curr->lockdep_depth - depth + 1; - hlock = curr->held_locks + depth-1; - /* - * Only non-recursive-read entries get new dependencies - * added: - */ - if (hlock->read != 2) { - if (!check_prev_add(curr, hlock, next, distance)) - return 0; - /* - * Stop after the first non-trylock entry, - * as non-trylock entries have added their - * own direct dependencies already, so this - * lock is connected to them indirectly: - */ - if (!hlock->trylock) - break; - } - depth--; - /* - * End of lock-stack? - */ - if (!depth) - break; - /* - * Stop the search if we cross into another context: - */ - if (curr->held_locks[depth].irq_context != - curr->held_locks[depth-1].irq_context) - break; - } - return 1; -out_bug: - if (!debug_locks_off_graph_unlock()) - return 0; - - WARN_ON(1); - - return 0; -} - -unsigned long nr_lock_chains; -static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; - -/* - * Look up a dependency chain. If the key is not present yet then - * add it and return 1 - in this case the new dependency chain is - * validated. If the key is already hashed, return 0. - * (On return with 1 graph_lock is held.) - */ -static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class) -{ - struct list_head *hash_head = chainhashentry(chain_key); - struct lock_chain *chain; - - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return 0; - /* - * We can walk it lock-free, because entries only get added - * to the hash: - */ - list_for_each_entry(chain, hash_head, entry) { - if (chain->chain_key == chain_key) { -cache_hit: - debug_atomic_inc(&chain_lookup_hits); - if (very_verbose(class)) - printk("\nhash chain already cached, key: " - "%016Lx tail class: [%p] %s\n", - (unsigned long long)chain_key, - class->key, class->name); - return 0; - } - } - if (very_verbose(class)) - printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", - (unsigned long long)chain_key, class->key, class->name); - /* - * Allocate a new chain entry from the static array, and add - * it to the hash: - */ - 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) { - graph_unlock(); - goto cache_hit; - } - } - if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { - 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; - } - chain = lock_chains + nr_lock_chains++; - chain->chain_key = chain_key; - list_add_tail_rcu(&chain->entry, hash_head); - debug_atomic_inc(&chain_lookup_misses); - inc_chains(); - - return 1; -} - -static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, - struct held_lock *hlock, int chain_head, u64 chain_key) -{ - /* - * Trylock needs to maintain the stack of held locks, but it - * does not add new dependencies, because trylock can be done - * in any order. - * - * 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 - * graph_lock for us) - */ - if (!hlock->trylock && (hlock->check == 2) && - lookup_chain_cache(chain_key, hlock->class)) { - /* - * Check whether last held lock: - * - * - is irq-safe, if this lock is irq-unsafe - * - is softirq-safe, if this lock is hardirq-unsafe - * - * And check whether the new lock's dependency graph - * could lead back to the previous lock. - * - * any of these scenarios could lead to a deadlock. If - * All validations - */ - int ret = check_deadlock(curr, hlock, lock, hlock->read); - - if (!ret) - return 0; - /* - * Mark recursive read, as we jump over it when - * building dependencies (just like we jump over - * trylock entries): - */ - if (ret == 2) - hlock->read = 2; - /* - * Add dependency only if this lock is not the head - * of the chain, and if it's not a secondary read-lock: - */ - if (!chain_head && ret != 2) - if (!check_prevs_add(curr, hlock)) - return 0; - graph_unlock(); - } else - /* after lookup_chain_cache(): */ - if (unlikely(!debug_locks)) - return 0; - - return 1; -} -#else -static inline int validate_chain(struct task_struct *curr, - struct lockdep_map *lock, struct held_lock *hlock, - int chain_head, u64 chain_key) -{ - return 1; -} -#endif - -/* - * We are building curr_chain_key incrementally, so double-check - * it from scratch, to make sure that it's done correctly: - */ -static void check_chain_key(struct task_struct *curr) -{ -#ifdef CONFIG_DEBUG_LOCKDEP - struct held_lock *hlock, *prev_hlock = NULL; - unsigned int i, id; - u64 chain_key = 0; - - for (i = 0; i < curr->lockdep_depth; i++) { - hlock = curr->held_locks + i; - if (chain_key != hlock->prev_chain_key) { - debug_locks_off(); - printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n", - curr->lockdep_depth, i, - (unsigned long long)chain_key, - (unsigned long long)hlock->prev_chain_key); - WARN_ON(1); - return; - } - id = hlock->class - lock_classes; - if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) - return; - - if (prev_hlock && (prev_hlock->irq_context != - hlock->irq_context)) - chain_key = 0; - chain_key = iterate_chain_key(chain_key, id); - prev_hlock = hlock; - } - if (chain_key != curr->curr_chain_key) { - debug_locks_off(); - printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n", - curr->lockdep_depth, i, - (unsigned long long)chain_key, - (unsigned long long)curr->curr_chain_key); - WARN_ON(1); - } -#endif -} - -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) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return 0; - - printk("\n=================================\n"); - printk( "[ INFO: inconsistent lock state ]\n"); - print_kernel_version(); - printk( "---------------------------------\n"); - - printk("inconsistent {%s} -> {%s} usage.\n", - usage_str[prev_bit], usage_str[new_bit]); - - printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", - curr->comm, task_pid_nr(curr), - trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, - trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, - trace_hardirqs_enabled(curr), - trace_softirqs_enabled(curr)); - print_lock(this); - - printk("{%s} state was registered at:\n", usage_str[prev_bit]); - print_stack_trace(this->class->usage_traces + prev_bit, 1); - - print_irqtrace_events(curr); - printk("\nother info that might help us debug this:\n"); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -/* - * Print out an error if an invalid bit is set: - */ -static inline int -valid_state(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) -{ - if (unlikely(this->class->usage_mask & (1 << bad_bit))) - return print_usage_bug(curr, this, bad_bit, new_bit); - return 1; -} - -static int mark_lock(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit); - -#ifdef CONFIG_TRACE_IRQFLAGS - -/* - * print irq inversion bug: - */ -static int -print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other, - struct held_lock *this, int forwards, - const char *irqclass) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return 0; - - printk("\n=========================================================\n"); - printk( "[ INFO: possible irq lock inversion dependency detected ]\n"); - print_kernel_version(); - printk( "---------------------------------------------------------\n"); - printk("%s/%d just changed the state of lock:\n", - curr->comm, task_pid_nr(curr)); - print_lock(this); - if (forwards) - printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass); - else - printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass); - print_lock_name(other); - printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); - - printk("\nother info that might help us debug this:\n"); - lockdep_print_held_locks(curr); - - printk("\nthe first lock's dependencies:\n"); - print_lock_dependencies(this->class, 0); - - printk("\nthe second lock's dependencies:\n"); - print_lock_dependencies(other, 0); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -/* - * Prove that in the forwards-direction subgraph starting at <this> - * there is no lock matching <mask>: - */ -static int -check_usage_forwards(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit bit, const char *irqclass) -{ - int ret; - - find_usage_bit = bit; - /* fills in <forwards_match> */ - ret = find_usage_forwards(this->class, 0); - if (!ret || ret == 1) - return ret; - - return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass); -} - -/* - * Prove that in the backwards-direction subgraph starting at <this> - * there is no lock matching <mask>: - */ -static int -check_usage_backwards(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit bit, const char *irqclass) -{ - int ret; - - find_usage_bit = bit; - /* fills in <backwards_match> */ - ret = find_usage_backwards(this->class, 0); - if (!ret || ret == 1) - return ret; - - return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass); -} - -void print_irqtrace_events(struct task_struct *curr) -{ - printk("irq event stamp: %u\n", curr->irq_events); - printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); - print_ip_sym(curr->hardirq_enable_ip); - printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); - print_ip_sym(curr->hardirq_disable_ip); - printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); - print_ip_sym(curr->softirq_enable_ip); - printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); - print_ip_sym(curr->softirq_disable_ip); -} - -static int hardirq_verbose(struct lock_class *class) -{ -#if HARDIRQ_VERBOSE - return class_filter(class); -#endif - return 0; -} - -static int softirq_verbose(struct lock_class *class) -{ -#if SOFTIRQ_VERBOSE - return class_filter(class); -#endif - return 0; -} - -#define STRICT_READ_CHECKS 1 - -static int mark_lock_irq(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit) -{ - int ret = 1; - - switch(new_bit) { - case LOCK_USED_IN_HARDIRQ: - if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) - return 0; - if (!valid_state(curr, this, new_bit, - LOCK_ENABLED_HARDIRQS_READ)) - return 0; - /* - * just marked it hardirq-safe, check that this lock - * took no hardirq-unsafe lock in the past: - */ - if (!check_usage_forwards(curr, this, - LOCK_ENABLED_HARDIRQS, "hard")) - return 0; -#if STRICT_READ_CHECKS - /* - * just marked it hardirq-safe, check that this lock - * took no hardirq-unsafe-read lock in the past: - */ - if (!check_usage_forwards(curr, this, - LOCK_ENABLED_HARDIRQS_READ, "hard-read")) - return 0; -#endif - if (hardirq_verbose(this->class)) - ret = 2; - break; - case LOCK_USED_IN_SOFTIRQ: - if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) - return 0; - if (!valid_state(curr, this, new_bit, - LOCK_ENABLED_SOFTIRQS_READ)) - return 0; - /* - * just marked it softirq-safe, check that this lock - * took no softirq-unsafe lock in the past: - */ - if (!check_usage_forwards(curr, this, - LOCK_ENABLED_SOFTIRQS, "soft")) - return 0; -#if STRICT_READ_CHECKS - /* - * just marked it softirq-safe, check that this lock - * took no softirq-unsafe-read lock in the past: - */ - if (!check_usage_forwards(curr, this, - LOCK_ENABLED_SOFTIRQS_READ, "soft-read")) - return 0; -#endif - if (softirq_verbose(this->class)) - ret = 2; - break; - case LOCK_USED_IN_HARDIRQ_READ: - if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) - return 0; - /* - * just marked it hardirq-read-safe, check that this lock - * took no hardirq-unsafe lock in the past: - */ - if (!check_usage_forwards(curr, this, - LOCK_ENABLED_HARDIRQS, "hard")) - return 0; - if (hardirq_verbose(this->class)) - ret = 2; - break; - case LOCK_USED_IN_SOFTIRQ_READ: - if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) - return 0; - /* - * just marked it softirq-read-safe, check that this lock - * took no softirq-unsafe lock in the past: - */ - if (!check_usage_forwards(curr, this, - LOCK_ENABLED_SOFTIRQS, "soft")) - return 0; - if (softirq_verbose(this->class)) - ret = 2; - break; - case LOCK_ENABLED_HARDIRQS: - if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) - return 0; - if (!valid_state(curr, this, new_bit, - LOCK_USED_IN_HARDIRQ_READ)) - return 0; - /* - * just marked it hardirq-unsafe, check that no hardirq-safe - * lock in the system ever took it in the past: - */ - if (!check_usage_backwards(curr, this, - LOCK_USED_IN_HARDIRQ, "hard")) - return 0; -#if STRICT_READ_CHECKS - /* - * just marked it hardirq-unsafe, check that no - * hardirq-safe-read lock in the system ever took - * it in the past: - */ - if (!check_usage_backwards(curr, this, - LOCK_USED_IN_HARDIRQ_READ, "hard-read")) - return 0; -#endif - if (hardirq_verbose(this->class)) - ret = 2; - break; - case LOCK_ENABLED_SOFTIRQS: - if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) - return 0; - if (!valid_state(curr, this, new_bit, - LOCK_USED_IN_SOFTIRQ_READ)) - return 0; - /* - * just marked it softirq-unsafe, check that no softirq-safe - * lock in the system ever took it in the past: - */ - if (!check_usage_backwards(curr, this, - LOCK_USED_IN_SOFTIRQ, "soft")) - return 0; -#if STRICT_READ_CHECKS - /* - * just marked it softirq-unsafe, check that no - * softirq-safe-read lock in the system ever took - * it in the past: - */ - if (!check_usage_backwards(curr, this, - LOCK_USED_IN_SOFTIRQ_READ, "soft-read")) - return 0; -#endif - if (softirq_verbose(this->class)) - ret = 2; - break; - case LOCK_ENABLED_HARDIRQS_READ: - if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) - return 0; -#if STRICT_READ_CHECKS - /* - * just marked it hardirq-read-unsafe, check that no - * hardirq-safe lock in the system ever took it in the past: - */ - if (!check_usage_backwards(curr, this, - LOCK_USED_IN_HARDIRQ, "hard")) - return 0; -#endif - if (hardirq_verbose(this->class)) - ret = 2; - break; - case LOCK_ENABLED_SOFTIRQS_READ: - if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) - return 0; -#if STRICT_READ_CHECKS - /* - * just marked it softirq-read-unsafe, check that no - * softirq-safe lock in the system ever took it in the past: - */ - if (!check_usage_backwards(curr, this, - LOCK_USED_IN_SOFTIRQ, "soft")) - return 0; -#endif - if (softirq_verbose(this->class)) - ret = 2; - break; - default: - WARN_ON(1); - break; - } - - return ret; -} - -/* - * Mark all held locks with a usage bit: - */ -static int -mark_held_locks(struct task_struct *curr, int hardirq) -{ - enum lock_usage_bit usage_bit; - struct held_lock *hlock; - int i; - - for (i = 0; i < curr->lockdep_depth; i++) { - hlock = curr->held_locks + i; - - if (hardirq) { - if (hlock->read) - usage_bit = LOCK_ENABLED_HARDIRQS_READ; - else - usage_bit = LOCK_ENABLED_HARDIRQS; - } else { - if (hlock->read) - usage_bit = LOCK_ENABLED_SOFTIRQS_READ; - else - usage_bit = LOCK_ENABLED_SOFTIRQS; - } - if (!mark_lock(curr, hlock, usage_bit)) - return 0; - } - - return 1; -} - -/* - * Debugging helper: via this flag we know that we are in - * 'early bootup code', and will warn about any invalid irqs-on event: - */ -static int early_boot_irqs_enabled; - -void early_boot_irqs_off(void) -{ - early_boot_irqs_enabled = 0; -} - -void early_boot_irqs_on(void) -{ - early_boot_irqs_enabled = 1; -} - -/* - * Hardirqs will be enabled: - */ -void trace_hardirqs_on(void) -{ - struct task_struct *curr = current; - unsigned long ip; - - if (unlikely(!debug_locks || current->lockdep_recursion)) - return; - - if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) - return; - - if (unlikely(curr->hardirqs_enabled)) { - debug_atomic_inc(&redundant_hardirqs_on); - return; - } - /* we'll do an OFF -> ON transition: */ - curr->hardirqs_enabled = 1; - ip = (unsigned long) __builtin_return_address(0); - - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) - return; - /* - * We are going to turn hardirqs on, so set the - * usage bit for all held locks: - */ - if (!mark_held_locks(curr, 1)) - return; - /* - * If we have softirqs enabled, then set the usage - * bit for all held locks. (disabled hardirqs prevented - * this bit from being set before) - */ - if (curr->softirqs_enabled) - if (!mark_held_locks(curr, 0)) - return; - - curr->hardirq_enable_ip = ip; - curr->hardirq_enable_event = ++curr->irq_events; - debug_atomic_inc(&hardirqs_on_events); -} - -EXPORT_SYMBOL(trace_hardirqs_on); - -/* - * Hardirqs were disabled: - */ -void trace_hardirqs_off(void) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks || current->lockdep_recursion)) - return; - - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - if (curr->hardirqs_enabled) { - /* - * We have done an ON -> OFF transition: - */ - curr->hardirqs_enabled = 0; - curr->hardirq_disable_ip = _RET_IP_; - curr->hardirq_disable_event = ++curr->irq_events; - debug_atomic_inc(&hardirqs_off_events); - } else - debug_atomic_inc(&redundant_hardirqs_off); -} - -EXPORT_SYMBOL(trace_hardirqs_off); - -/* - * Softirqs will be enabled: - */ -void trace_softirqs_on(unsigned long ip) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks)) - return; - - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - if (curr->softirqs_enabled) { - debug_atomic_inc(&redundant_softirqs_on); - return; - } - - /* - * We'll do an OFF -> ON transition: - */ - curr->softirqs_enabled = 1; - curr->softirq_enable_ip = ip; - curr->softirq_enable_event = ++curr->irq_events; - debug_atomic_inc(&softirqs_on_events); - /* - * We are going to turn softirqs on, so set the - * usage bit for all held locks, if hardirqs are - * enabled too: - */ - if (curr->hardirqs_enabled) - mark_held_locks(curr, 0); -} - -/* - * Softirqs were disabled: - */ -void trace_softirqs_off(unsigned long ip) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks)) - return; - - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - if (curr->softirqs_enabled) { - /* - * We have done an ON -> OFF transition: - */ - curr->softirqs_enabled = 0; - curr->softirq_disable_ip = ip; - curr->softirq_disable_event = ++curr->irq_events; - debug_atomic_inc(&softirqs_off_events); - DEBUG_LOCKS_WARN_ON(!softirq_count()); - } else - debug_atomic_inc(&redundant_softirqs_off); -} - -static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) -{ - /* - * If non-trylock use in a hardirq or softirq context, then - * mark the lock as used in these contexts: - */ - if (!hlock->trylock) { - if (hlock->read) { - if (curr->hardirq_context) - if (!mark_lock(curr, hlock, - LOCK_USED_IN_HARDIRQ_READ)) - return 0; - if (curr->softirq_context) - if (!mark_lock(curr, hlock, - LOCK_USED_IN_SOFTIRQ_READ)) - return 0; - } else { - if (curr->hardirq_context) - if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) - return 0; - if (curr->softirq_context) - if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) - return 0; - } - } - if (!hlock->hardirqs_off) { - if (hlock->read) { - if (!mark_lock(curr, hlock, - LOCK_ENABLED_HARDIRQS_READ)) - return 0; - if (curr->softirqs_enabled) - if (!mark_lock(curr, hlock, - LOCK_ENABLED_SOFTIRQS_READ)) - return 0; - } else { - if (!mark_lock(curr, hlock, - LOCK_ENABLED_HARDIRQS)) - return 0; - if (curr->softirqs_enabled) - if (!mark_lock(curr, hlock, - LOCK_ENABLED_SOFTIRQS)) - return 0; - } - } - - return 1; -} - -static int separate_irq_context(struct task_struct *curr, - struct held_lock *hlock) -{ - unsigned int depth = curr->lockdep_depth; - - /* - * Keep track of points where we cross into an interrupt context: - */ - hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + - curr->softirq_context; - if (depth) { - struct held_lock *prev_hlock; - - prev_hlock = curr->held_locks + depth-1; - /* - * If we cross into another context, reset the - * hash key (this also prevents the checking and the - * adding of the dependency to 'prev'): - */ - if (prev_hlock->irq_context != hlock->irq_context) - return 1; - } - return 0; -} - -#else - -static inline -int mark_lock_irq(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit) -{ - WARN_ON(1); - return 1; -} - -static inline int mark_irqflags(struct task_struct *curr, - struct held_lock *hlock) -{ - return 1; -} - -static inline int separate_irq_context(struct task_struct *curr, - struct held_lock *hlock) -{ - return 0; -} - -#endif - -/* - * Mark a lock with a usage bit, and validate the state transition: - */ -static int mark_lock(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit) -{ - unsigned int new_mask = 1 << new_bit, ret = 1; - - /* - * If already set then do not dirty the cacheline, - * nor do any checks: - */ - if (likely(this->class->usage_mask & new_mask)) - return 1; - - if (!graph_lock()) - return 0; - /* - * Make sure we didnt race: - */ - if (unlikely(this->class->usage_mask & new_mask)) { - graph_unlock(); - return 1; - } - - this->class->usage_mask |= new_mask; - - if (!save_trace(this->class->usage_traces + new_bit)) - return 0; - - switch (new_bit) { - case LOCK_USED_IN_HARDIRQ: - case LOCK_USED_IN_SOFTIRQ: - case LOCK_USED_IN_HARDIRQ_READ: - case LOCK_USED_IN_SOFTIRQ_READ: - case LOCK_ENABLED_HARDIRQS: - case LOCK_ENABLED_SOFTIRQS: - case LOCK_ENABLED_HARDIRQS_READ: - case LOCK_ENABLED_SOFTIRQS_READ: - ret = mark_lock_irq(curr, this, new_bit); - if (!ret) - return 0; - break; - case LOCK_USED: - debug_atomic_dec(&nr_unused_locks); - break; - default: - if (!debug_locks_off_graph_unlock()) - return 0; - WARN_ON(1); - return 0; - } - - graph_unlock(); - - /* - * We must printk outside of the graph_lock: - */ - if (ret == 2) { - printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); - print_lock(this); - print_irqtrace_events(curr); - dump_stack(); - } - - return ret; -} - -/* - * Initialize a lock instance's lock-class mapping info: - */ -void lockdep_init_map(struct lockdep_map *lock, const char *name, - struct lock_class_key *key, int subclass) -{ - if (unlikely(!debug_locks)) - return; - - if (DEBUG_LOCKS_WARN_ON(!key)) - return; - if (DEBUG_LOCKS_WARN_ON(!name)) - return; - /* - * Sanity check, the lock-class key must be persistent: - */ - if (!static_obj(key)) { - printk("BUG: key %p not in .data!\n", key); - DEBUG_LOCKS_WARN_ON(1); - return; - } - lock->name = name; - lock->key = key; - lock->class_cache = NULL; -#ifdef CONFIG_LOCK_STAT - lock->cpu = raw_smp_processor_id(); -#endif - if (subclass) - register_lock_class(lock, subclass, 1); -} - -EXPORT_SYMBOL_GPL(lockdep_init_map); - -/* - * This gets called for every mutex_lock*()/spin_lock*() operation. - * We maintain the dependency maps and validate the locking attempt: - */ -static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, - int trylock, int read, int check, int hardirqs_off, - unsigned long ip) -{ - struct task_struct *curr = current; - struct lock_class *class = NULL; - struct held_lock *hlock; - unsigned int depth, id; - int chain_head = 0; - u64 chain_key; - - if (!prove_locking) - check = 1; - - if (unlikely(!debug_locks)) - return 0; - - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return 0; - - if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { - debug_locks_off(); - printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n"); - printk("turning off the locking correctness validator.\n"); - return 0; - } - - if (!subclass) - class = lock->class_cache; - /* - * Not cached yet or subclass? - */ - if (unlikely(!class)) { - class = register_lock_class(lock, subclass, 0); - if (!class) - return 0; - } - debug_atomic_inc((atomic_t *)&class->ops); - if (very_verbose(class)) { - printk("\nacquire class [%p] %s", class->key, class->name); - if (class->name_version > 1) - printk("#%d", class->name_version); - printk("\n"); - dump_stack(); - } - - /* - * Add the lock to the list of currently held locks. - * (we dont increase the depth just yet, up until the - * dependency checks are done) - */ - depth = curr->lockdep_depth; - if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) - return 0; - - hlock = curr->held_locks + depth; - - hlock->class = class; - hlock->acquire_ip = ip; - hlock->instance = lock; - hlock->trylock = trylock; - hlock->read = read; - hlock->check = check; - hlock->hardirqs_off = hardirqs_off; -#ifdef CONFIG_LOCK_STAT - hlock->waittime_stamp = 0; - hlock->holdtime_stamp = sched_clock(); -#endif - - if (check == 2 && !mark_irqflags(curr, hlock)) - return 0; - - /* mark it as used: */ - if (!mark_lock(curr, hlock, LOCK_USED)) - return 0; - - /* - * Calculate the chain hash: it's the combined hash of all the - * lock keys along the dependency chain. We save the hash value - * at every step so that we can get the current hash easily - * after unlock. The chain hash is then used to cache dependency - * results. - * - * The 'key ID' is what is the most compact key value to drive - * the hash, not class->key. - */ - id = class - lock_classes; - if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) - return 0; - - chain_key = curr->curr_chain_key; - if (!depth) { - if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) - return 0; - chain_head = 1; - } - - hlock->prev_chain_key = chain_key; - if (separate_irq_context(curr, hlock)) { - chain_key = 0; - chain_head = 1; - } - chain_key = iterate_chain_key(chain_key, id); - - if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) - return 0; - - curr->curr_chain_key = chain_key; - curr->lockdep_depth++; - check_chain_key(curr); -#ifdef CONFIG_DEBUG_LOCKDEP - if (unlikely(!debug_locks)) - return 0; -#endif - if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { - debug_locks_off(); - printk("BUG: MAX_LOCK_DEPTH too low!\n"); - printk("turning off the locking correctness validator.\n"); - return 0; - } - - if (unlikely(curr->lockdep_depth > max_lockdep_depth)) - max_lockdep_depth = curr->lockdep_depth; - - return 1; -} - -static int -print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, - unsigned long ip) -{ - if (!debug_locks_off()) - return 0; - if (debug_locks_silent) - return 0; - - printk("\n=====================================\n"); - printk( "[ BUG: bad unlock balance detected! ]\n"); - printk( "-------------------------------------\n"); - printk("%s/%d is trying to release lock (", - curr->comm, task_pid_nr(curr)); - print_lockdep_cache(lock); - printk(") at:\n"); - print_ip_sym(ip); - printk("but there are no more locks to release!\n"); - printk("\nother info that might help us debug this:\n"); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -/* - * Common debugging checks for both nested and non-nested unlock: - */ -static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, - unsigned long ip) -{ - if (unlikely(!debug_locks)) - return 0; - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return 0; - - if (curr->lockdep_depth <= 0) - return print_unlock_inbalance_bug(curr, lock, ip); - - return 1; -} - -/* - * Remove the lock to the list of currently held locks in a - * potentially non-nested (out of order) manner. This is a - * relatively rare operation, as all the unlock APIs default - * to nested mode (which uses lock_release()): - */ -static int -lock_release_non_nested(struct task_struct *curr, - struct lockdep_map *lock, unsigned long ip) -{ - struct held_lock *hlock, *prev_hlock; - unsigned int depth; - int i; - - /* - * Check whether the lock exists in the current stack - * of held locks: - */ - depth = curr->lockdep_depth; - if (DEBUG_LOCKS_WARN_ON(!depth)) - return 0; - - prev_hlock = NULL; - for (i = depth-1; i >= 0; i--) { - hlock = curr->held_locks + i; - /* - * We must not cross into another context: - */ - if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) - break; - if (hlock->instance == lock) - goto found_it; - prev_hlock = hlock; - } - return print_unlock_inbalance_bug(curr, lock, ip); - -found_it: - lock_release_holdtime(hlock); - - /* - * We have the right lock to unlock, 'hlock' points to it. - * Now we remove it from the stack, and add back the other - * entries (if any), recalculating the hash along the way: - */ - curr->lockdep_depth = i; - curr->curr_chain_key = hlock->prev_chain_key; - - for (i++; i < depth; i++) { - hlock = curr->held_locks + i; - if (!__lock_acquire(hlock->instance, - hlock->class->subclass, hlock->trylock, - hlock->read, hlock->check, hlock->hardirqs_off, - hlock->acquire_ip)) - return 0; - } - - if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) - return 0; - return 1; -} - -/* - * Remove the lock to the list of currently held locks - this gets - * called on mutex_unlock()/spin_unlock*() (or on a failed - * mutex_lock_interruptible()). This is done for unlocks that nest - * perfectly. (i.e. the current top of the lock-stack is unlocked) - */ -static int lock_release_nested(struct task_struct *curr, - struct lockdep_map *lock, unsigned long ip) -{ - struct held_lock *hlock; - unsigned int depth; - - /* - * Pop off the top of the lock stack: - */ - depth = curr->lockdep_depth - 1; - hlock = curr->held_locks + depth; - - /* - * Is the unlock non-nested: - */ - if (hlock->instance != lock) - return lock_release_non_nested(curr, lock, ip); - curr->lockdep_depth--; - - if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) - return 0; - - curr->curr_chain_key = hlock->prev_chain_key; - - lock_release_holdtime(hlock); - -#ifdef CONFIG_DEBUG_LOCKDEP - hlock->prev_chain_key = 0; - hlock->class = NULL; - hlock->acquire_ip = 0; - hlock->irq_context = 0; -#endif - return 1; -} - -/* - * Remove the lock to the list of currently held locks - this gets - * called on mutex_unlock()/spin_unlock*() (or on a failed - * mutex_lock_interruptible()). This is done for unlocks that nest - * perfectly. (i.e. the current top of the lock-stack is unlocked) - */ -static void -__lock_release(struct lockdep_map *lock, int nested, unsigned long ip) -{ - struct task_struct *curr = current; - - if (!check_unlock(curr, lock, ip)) - return; - - if (nested) { - if (!lock_release_nested(curr, lock, ip)) - return; - } else { - if (!lock_release_non_nested(curr, lock, ip)) - return; - } - - check_chain_key(curr); -} - -/* - * Check whether we follow the irq-flags state precisely: - */ -static void check_flags(unsigned long flags) -{ -#if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS) - if (!debug_locks) - return; - - if (irqs_disabled_flags(flags)) { - if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { - printk("possible reason: unannotated irqs-off.\n"); - } - } else { - if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { - printk("possible reason: unannotated irqs-on.\n"); - } - } - - /* - * We dont accurately track softirq state in e.g. - * hardirq contexts (such as on 4KSTACKS), so only - * check if not in hardirq contexts: - */ - if (!hardirq_count()) { - if (softirq_count()) - DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); - else - DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); - } - - if (!debug_locks) - print_irqtrace_events(current); -#endif -} - -/* - * We are not always called with irqs disabled - do that here, - * and also avoid lockdep recursion: - */ -void lock_acquire(struct lockdep_map *lock, unsigned int subclass, - int trylock, int read, int check, unsigned long ip) -{ - unsigned long flags; - - if (unlikely(!lock_stat && !prove_locking)) - return; - - if (unlikely(current->lockdep_recursion)) - return; - - raw_local_irq_save(flags); - check_flags(flags); - - current->lockdep_recursion = 1; - __lock_acquire(lock, subclass, trylock, read, check, - irqs_disabled_flags(flags), ip); - current->lockdep_recursion = 0; - raw_local_irq_restore(flags); -} - -EXPORT_SYMBOL_GPL(lock_acquire); - -void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) -{ - unsigned long flags; - - if (unlikely(!lock_stat && !prove_locking)) - return; - - if (unlikely(current->lockdep_recursion)) - return; - - raw_local_irq_save(flags); - check_flags(flags); - current->lockdep_recursion = 1; - __lock_release(lock, nested, ip); - current->lockdep_recursion = 0; - raw_local_irq_restore(flags); -} - -EXPORT_SYMBOL_GPL(lock_release); - -#ifdef CONFIG_LOCK_STAT -static int -print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, - unsigned long ip) -{ - if (!debug_locks_off()) - return 0; - if (debug_locks_silent) - return 0; - - printk("\n=================================\n"); - printk( "[ BUG: bad contention detected! ]\n"); - printk( "---------------------------------\n"); - printk("%s/%d is trying to contend lock (", - curr->comm, task_pid_nr(curr)); - print_lockdep_cache(lock); - printk(") at:\n"); - print_ip_sym(ip); - printk("but there are no locks held!\n"); - printk("\nother info that might help us debug this:\n"); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); - - return 0; -} - -static void -__lock_contended(struct lockdep_map *lock, unsigned long ip) -{ - struct task_struct *curr = current; - struct held_lock *hlock, *prev_hlock; - struct lock_class_stats *stats; - unsigned int depth; - int i, point; - - depth = curr->lockdep_depth; - if (DEBUG_LOCKS_WARN_ON(!depth)) - return; - - prev_hlock = NULL; - for (i = depth-1; i >= 0; i--) { - hlock = curr->held_locks + i; - /* - * We must not cross into another context: - */ - if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) - break; - if (hlock->instance == lock) - goto found_it; - prev_hlock = hlock; - } - print_lock_contention_bug(curr, lock, ip); - return; - -found_it: - hlock->waittime_stamp = sched_clock(); - - point = lock_contention_point(hlock->class, ip); - - stats = get_lock_stats(hlock->class); - if (point < ARRAY_SIZE(stats->contention_point)) - stats->contention_point[i]++; - if (lock->cpu != smp_processor_id()) - stats->bounces[bounce_contended + !!hlock->read]++; - put_lock_stats(stats); -} - -static void -__lock_acquired(struct lockdep_map *lock) -{ - struct task_struct *curr = current; - struct held_lock *hlock, *prev_hlock; - struct lock_class_stats *stats; - unsigned int depth; - u64 now; - s64 waittime = 0; - int i, cpu; - - depth = curr->lockdep_depth; - if (DEBUG_LOCKS_WARN_ON(!depth)) - return; - - prev_hlock = NULL; - for (i = depth-1; i >= 0; i--) { - hlock = curr->held_locks + i; - /* - * We must not cross into another context: - */ - if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) - break; - if (hlock->instance == lock) - goto found_it; - prev_hlock = hlock; - } - print_lock_contention_bug(curr, lock, _RET_IP_); - return; - -found_it: - cpu = smp_processor_id(); - if (hlock->waittime_stamp) { - now = sched_clock(); - waittime = now - hlock->waittime_stamp; - hlock->holdtime_stamp = now; - } - - stats = get_lock_stats(hlock->class); - if (waittime) { - if (hlock->read) - lock_time_inc(&stats->read_waittime, waittime); - else - lock_time_inc(&stats->write_waittime, waittime); - } - if (lock->cpu != cpu) - stats->bounces[bounce_acquired + !!hlock->read]++; - put_lock_stats(stats); - - lock->cpu = cpu; -} - -void lock_contended(struct lockdep_map *lock, unsigned long ip) -{ - unsigned long flags; - - if (unlikely(!lock_stat)) - return; - - if (unlikely(current->lockdep_recursion)) - return; - - raw_local_irq_save(flags); - check_flags(flags); - current->lockdep_recursion = 1; - __lock_contended(lock, ip); - current->lockdep_recursion = 0; - raw_local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(lock_contended); - -void lock_acquired(struct lockdep_map *lock) -{ - unsigned long flags; - - if (unlikely(!lock_stat)) - return; - - if (unlikely(current->lockdep_recursion)) - return; - - raw_local_irq_save(flags); - check_flags(flags); - current->lockdep_recursion = 1; - __lock_acquired(lock); - current->lockdep_recursion = 0; - raw_local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(lock_acquired); -#endif - -/* - * Used by the testsuite, sanitize the validator state - * after a simulated failure: - */ - -void lockdep_reset(void) -{ - unsigned long flags; - int i; - - raw_local_irq_save(flags); - current->curr_chain_key = 0; - current->lockdep_depth = 0; - current->lockdep_recursion = 0; - memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); - nr_hardirq_chains = 0; - nr_softirq_chains = 0; - nr_process_chains = 0; - debug_locks = 1; - for (i = 0; i < CHAINHASH_SIZE; i++) - INIT_LIST_HEAD(chainhash_table + i); - raw_local_irq_restore(flags); -} - -static void zap_class(struct lock_class *class) -{ - 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); - } - /* - * Unhash the class and remove it from the all_lock_classes list: - */ - list_del_rcu(&class->hash_entry); - list_del_rcu(&class->lock_entry); - -} - -static inline int within(const void *addr, void *start, unsigned long size) -{ - return addr >= start && addr < start + size; -} - -void lockdep_free_key_range(void *start, unsigned long size) -{ - struct lock_class *class, *next; - struct list_head *head; - unsigned long flags; - int i; - int locked; - - raw_local_irq_save(flags); - locked = graph_lock(); - - /* - * Unhash all classes that were created by this module: - */ - 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 (within(class->key, start, size)) - zap_class(class); - else if (within(class->name, start, size)) - zap_class(class); - } - } - - if (locked) - graph_unlock(); - raw_local_irq_restore(flags); -} - -void lockdep_reset_lock(struct lockdep_map *lock) -{ - struct lock_class *class, *next; - struct list_head *head; - unsigned long flags; - int i, j; - int locked; - - raw_local_irq_save(flags); - - /* - * Remove all classes this lock might have: - */ - for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { - /* - * If the class exists we look it up and zap it: - */ - class = look_up_lock_class(lock, j); - if (class) - zap_class(class); - } - /* - * Debug check: in the end all mapped classes should - * be gone. - */ - locked = 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)) { - if (debug_locks_off_graph_unlock()) - WARN_ON(1); - goto out_restore; - } - } - } - if (locked) - graph_unlock(); - -out_restore: - raw_local_irq_restore(flags); -} - -void lockdep_init(void) -{ - int i; - - /* - * Some architectures have their own start_kernel() - * code which calls lockdep_init(), while we also - * call lockdep_init() from the start_kernel() itself, - * and we want to initialize the hashes only once: - */ - if (lockdep_initialized) - return; - - for (i = 0; i < CLASSHASH_SIZE; i++) - INIT_LIST_HEAD(classhash_table + i); - - for (i = 0; i < CHAINHASH_SIZE; i++) - INIT_LIST_HEAD(chainhash_table + i); - - lockdep_initialized = 1; -} - -void __init lockdep_info(void) -{ - printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); - - printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); - printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); - printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); - printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); - printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); - printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); - printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); - - printk(" memory used by lock dependency info: %lu kB\n", - (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + - sizeof(struct list_head) * CLASSHASH_SIZE + - sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + - sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + - sizeof(struct list_head) * CHAINHASH_SIZE) / 1024); - - printk(" per task-struct memory footprint: %lu bytes\n", - sizeof(struct held_lock) * MAX_LOCK_DEPTH); - -#ifdef CONFIG_DEBUG_LOCKDEP - if (lockdep_init_error) { - printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n"); - printk("Call stack leading to lockdep invocation was:\n"); - print_stack_trace(&lockdep_init_trace, 0); - } -#endif -} - -static void -print_freed_lock_bug(struct task_struct *curr, const void *mem_from, - const void *mem_to, struct held_lock *hlock) -{ - if (!debug_locks_off()) - return; - if (debug_locks_silent) - return; - - printk("\n=========================\n"); - printk( "[ BUG: held lock freed! ]\n"); - printk( "-------------------------\n"); - printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", - curr->comm, task_pid_nr(curr), mem_from, mem_to-1); - print_lock(hlock); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); -} - -static inline int not_in_range(const void* mem_from, unsigned long mem_len, - const void* lock_from, unsigned long lock_len) -{ - return lock_from + lock_len <= mem_from || - mem_from + mem_len <= lock_from; -} - -/* - * Called when kernel memory is freed (or unmapped), or if a lock - * is destroyed or reinitialized - this code checks whether there is - * any held lock in the memory range of <from> to <to>: - */ -void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) -{ - struct task_struct *curr = current; - struct held_lock *hlock; - unsigned long flags; - int i; - - if (unlikely(!debug_locks)) - return; - - local_irq_save(flags); - for (i = 0; i < curr->lockdep_depth; i++) { - hlock = curr->held_locks + i; - - if (not_in_range(mem_from, mem_len, hlock->instance, - sizeof(*hlock->instance))) - continue; - - print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); - break; - } - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); - -static void print_held_locks_bug(struct task_struct *curr) -{ - if (!debug_locks_off()) - return; - if (debug_locks_silent) - return; - - printk("\n=====================================\n"); - printk( "[ BUG: lock held at task exit time! ]\n"); - printk( "-------------------------------------\n"); - printk("%s/%d is exiting with locks still held!\n", - curr->comm, task_pid_nr(curr)); - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); -} - -void debug_check_no_locks_held(struct task_struct *task) -{ - if (unlikely(task->lockdep_depth > 0)) - print_held_locks_bug(task); -} - -void debug_show_all_locks(void) -{ - struct task_struct *g, *p; - int count = 10; - int unlock = 1; - - if (unlikely(!debug_locks)) { - printk("INFO: lockdep is turned off.\n"); - return; - } - printk("\nShowing all locks held in the system:\n"); - - /* - * Here we try to get the tasklist_lock as hard as possible, - * if not successful after 2 seconds we ignore it (but keep - * trying). This is to enable a debug printout even if a - * tasklist_lock-holding task deadlocks or crashes. - */ -retry: - if (!read_trylock(&tasklist_lock)) { - if (count == 10) - printk("hm, tasklist_lock locked, retrying... "); - if (count) { - count--; - printk(" #%d", 10-count); - mdelay(200); - goto retry; - } - printk(" ignoring it.\n"); - unlock = 0; - } - if (count != 10) - printk(" locked it.\n"); - - do_each_thread(g, p) { - /* - * It's not reliable to print a task's held locks - * if it's not sleeping (or if it's not the current - * task): - */ - if (p->state == TASK_RUNNING && p != current) - continue; - if (p->lockdep_depth) - lockdep_print_held_locks(p); - if (!unlock) - if (read_trylock(&tasklist_lock)) - unlock = 1; - } while_each_thread(g, p); - - printk("\n"); - printk("=============================================\n\n"); - - if (unlock) - read_unlock(&tasklist_lock); -} - -EXPORT_SYMBOL_GPL(debug_show_all_locks); - -/* - * Careful: only use this function if you are sure that - * the task cannot run in parallel! - */ -void __debug_show_held_locks(struct task_struct *task) -{ - if (unlikely(!debug_locks)) { - printk("INFO: lockdep is turned off.\n"); - return; - } - lockdep_print_held_locks(task); -} -EXPORT_SYMBOL_GPL(__debug_show_held_locks); - -void debug_show_held_locks(struct task_struct *task) -{ - __debug_show_held_locks(task); -} - -EXPORT_SYMBOL_GPL(debug_show_held_locks); - -void lockdep_sys_exit(void) -{ - struct task_struct *curr = current; - - if (unlikely(curr->lockdep_depth)) { - if (!debug_locks_off()) - return; - printk("\n================================================\n"); - printk( "[ BUG: lock held when returning to user space! ]\n"); - printk( "------------------------------------------------\n"); - printk("%s/%d is leaving the kernel with locks still held!\n", - curr->comm, curr->pid); - lockdep_print_held_locks(curr); - } -} |