/*
* 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 <linux/ftrace.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;
}
/* prevent any recursions within lockdep from causing deadlocks */
current->lockdep_recursion++;
return 1;
}
static inline int graph_unlock(void)
{
if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
return DEBUG_LOCKS_WARN_ON(1);
current->lockdep_recursion--;
__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];
static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
if (!hlock->class_idx) {
DEBUG_LOCKS_WARN_ON(1);
return NULL;
}
return lock_classes + hlock->class_idx - 1;
}
#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(hlock));
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;
static unsigned int lockdep_dependency_gen_id;
static bool lockdep_dependency_visit(struct lock_class *source,
unsigned int depth)
{
if (!depth)
lockdep_dependency_gen_id++;
if (source->dep_gen_id == lockdep_dependency_gen_id)
return true;
source->dep_gen_id = lockdep_dependency_gen_id;
return false;
}
#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(hlock));
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 (lockdep_dependency_visit(class, depth))
return;
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 = hlock_class(check_source);
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;
}
unsigned long __lockdep_count_forward_deps(struct lock_class *class,
unsigned int depth)
{
struct lock_list *entry;
unsigned long ret = 1;
if (lockdep_dependency_visit(class, depth))
return 0;
/*
* Recurse this class's dependency list:
*/
list_for_each_entry(entry, &class->locks_after, entry)
ret += __lockdep_count_forward_deps(entry->class, depth + 1);
return ret;
}
unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
unsigned long ret, flags;
local_irq_save(flags);
__raw_spin_lock(&lockdep_lock);
ret = __lockdep_count_forward_deps(class, 0);
__raw_spin_unlock(&lockdep_lock);
local_irq_restore(flags);
return ret;
}
unsigned long __lockdep_count_backward_deps(struct lock_class *class,
unsigned int depth)
{
struct lock_list *entry;
unsigned long ret = 1;
if (lockdep_dependency_visit(class, depth))
return 0;
/*
* Recurse this class's dependency list:
*/
list_for_each_entry(entry, &class->locks_before, entry)
ret += __lockdep_count_backward_deps(entry->class, depth + 1);
return ret;
}
unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
unsigned long ret, flags;
local_irq_save(flags);
__raw_spin_lock(&lockdep_lock);
ret = __lockdep_count_backward_deps(class, 0);
__raw_spin_unlock(&lockdep_lock);
local_irq_restore(flags);
return ret;
}
/*
* 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;
if (lockdep_dependency_visit(source, depth))
return 1;
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 == hlock_class(check_target))
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;
}
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* 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 (lockdep_dependency_visit(source, depth))
return 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_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 (lockdep_dependency_visit(source, depth))
return 1;
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;
}
if (!source && debug_locks_off_graph_unlock()) {
WARN_ON(1);
return 0;
}
/*
* 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(hlock_class(prev));
printk(" ->");
print_lock_name(hlock_class(next));
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(hlock_class(prev), 0);
if (!ret || ret == 1)
return ret;
find_usage_bit = bit_forwards;
ret = find_usage_forwards(hlock_class(next), 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;
struct held_lock *nest = NULL;
int i;
for (i = 0; i < curr->lockdep_depth; i++) {
prev = curr->held_locks + i;
if (prev->instance == next->nest_lock)
nest = prev;
if (hlock_class(prev) != hlock_class(next))
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;
/*
* We're holding the nest_lock, which serializes this lock's
* nesting behaviour.
*/
if (nest)
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(hlock_class(next), 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, &hlock_class(prev)->locks_after, entry) {
if (entry->class == hlock_class(next)) {
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(hlock_class(prev), hlock_class(next),
&hlock_class(prev)->locks_after,
next->acquire_ip, distance);
if (!ret)
return 0;
ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
&hlock_class(next)->locks_before,
next->acquire_ip, distance);
if (!ret)
return 0;
/*
* Debugging printouts:
*/
if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
graph_unlock();
printk("\n new dependency: ");
print_lock_name(hlock_class(prev));
printk(" => ");
print_lock_name(hlock_class(next));
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;
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
int nr_chain_hlocks;
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
{
return lock_classes + chain_hlocks[chain->base + i];
}
/*
* 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(struct task_struct *curr,
struct held_lock *hlock,
u64 chain_key)
{
struct lock_class *class = hlock_class(hlock);
struct list_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
struct held_lock *hlock_curr, *hlock_next;
int i, j, n, cn;
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;
chain->irq_context = hlock->irq_context;
/* Find the first held_lock of current chain */
hlock_next = hlock;
for (i = curr->lockdep_depth - 1; i >= 0; i--) {
hlock_curr = curr->held_locks + i;
if (hlock_curr->irq_context != hlock_next->irq_context)
break;
hlock_next = hlock;
}
i++;
chain->depth = curr->lockdep_depth + 1 - i;
cn = nr_chain_hlocks;
while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
if (n == cn)
break;
cn = n;
}
if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
chain->base = cn;
for (j = 0; j < chain->depth - 1; j++, i++) {
int lock_id = curr->held_locks[i].class_idx - 1;
chain_hlocks[chain->base + j] = lock_id;
}
chain_hlocks[chain->base + j] = class - lock_classes;
}
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(curr, hlock, chain_key)) {
/*
* 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_idx - 1;
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(hlock_class(this)->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(hlock_class(this)->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);
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* 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(hlock_class(this), 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(hlock_class(this), 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(hlock_class(this), 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(hlock_class(this)))
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(hlock_class(this)))
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(hlock_class(this)))
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(hlock_class(this)))
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(hlock_class(this)))
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(hlock_class(this)))
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(hlock_class(this)))
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(hlock_class(this)))
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_caller(unsigned long a0)
{
struct task_struct *curr = current;
unsigned long ip;
time_hardirqs_on(CALLER_ADDR0, a0);
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_caller);
void trace_hardirqs_on(void)
{
trace_hardirqs_on_caller(CALLER_ADDR0);
}
EXPORT_SYMBOL(trace_hardirqs_on);
/*
* Hardirqs were disabled:
*/
void trace_hardirqs_off_caller(unsigned long a0)
{
struct task_struct *curr = current;
time_hardirqs_off(CALLER_ADDR0, a0);
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_caller);
void trace_hardirqs_off(void)
{
trace_hardirqs_off_caller(CALLER_ADDR0);
}
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(hlock_class(this)->usage_mask & new_mask))
return 1;
if (!graph_lock())
return 0;
/*
* Make sure we didnt race:
*/
if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
graph_unlock();
return 1;
}
hlock_class(this)->usage_mask |= new_mask;
if (!save_trace(hlock_class(this)->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,
struct lockdep_map *nest_lock, 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;
if (DEBUG_LOCKS_WARN_ON(!class))
return 0;
hlock->class_idx = class - lock_classes + 1;
hlock->acquire_ip = ip;
hlock->instance = lock;
hlock->nest_lock = nest_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;
}
static int
__lock_set_subclass(struct lockdep_map *lock,
unsigned int subclass, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock, *prev_hlock;
struct lock_class *class;
unsigned int depth;
int i;
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:
class = register_lock_class(lock, subclass, 0);
hlock->class_idx = class - lock_classes + 1;
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
for (; i < depth; i++) {
hlock = curr->held_locks + i;
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass, hlock->trylock,
hlock->read, hlock->check, hlock->hardirqs_off,
hlock->nest_lock, hlock->acquire_ip))
return 0;
}
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
return 0;
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(hlock)->subclass, hlock->trylock,
hlock->read, hlock->check, hlock->hardirqs_off,
hlock->nest_lock, 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_idx = 0;
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_PROVE_LOCKING) && 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
}
void
lock_set_subclass(struct lockdep_map *lock,
unsigned int subclass, unsigned long ip)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
current->lockdep_recursion = 1;
check_flags(flags);
if (__lock_set_subclass(lock, subclass, ip))
check_chain_key(current);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_set_subclass);
/*
* 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,
struct lockdep_map *nest_lock, unsigned long ip)
{
unsigned long flags;
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), nest_lock, 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(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(hlock), ip);
stats = get_lock_stats(hlock_class(hlock));
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(hlock));
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);
class->key = NULL;
}
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);
}
}
