| /* |
| * 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. |
| */ |
| #define DISABLE_BRANCH_PROFILING |
| #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 <linux/stringify.h> |
| #include <linux/bitops.h> |
| #include <linux/gfp.h> |
| #include <linux/kmemcheck.h> |
| |
| #include <asm/sections.h> |
| |
| #include "lockdep_internals.h" |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/lock.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 arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
| |
| static int graph_lock(void) |
| { |
| arch_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) { |
| arch_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 && !arch_spin_is_locked(&lockdep_lock)) { |
| /* |
| * The lockdep graph lock isn't locked while we expect it to |
| * be, we're confused now, bye! |
| */ |
| return DEBUG_LOCKS_WARN_ON(1); |
| } |
| |
| current->lockdep_recursion--; |
| arch_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(); |
| |
| arch_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) { |
| /* |
| * Someone passed in garbage, we give up. |
| */ |
| 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], |
| cpu_lock_stats); |
| |
| static inline u64 lockstat_clock(void) |
| { |
| return local_clock(); |
| } |
| |
| static int lock_point(unsigned long points[], unsigned long ip) |
| { |
| int i; |
| |
| for (i = 0; i < LOCKSTAT_POINTS; i++) { |
| if (points[i] == 0) { |
| points[i] = ip; |
| break; |
| } |
| if (points[i] == ip) |
| break; |
| } |
| |
| return i; |
| } |
| |
| static void lock_time_inc(struct lock_time *lt, u64 time) |
| { |
| if (time > lt->max) |
| lt->max = time; |
| |
| if (time < lt->min || !lt->nr) |
| lt->min = time; |
| |
| lt->total += time; |
| lt->nr++; |
| } |
| |
| static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
| { |
| if (!src->nr) |
| return; |
| |
| if (src->max > dst->max) |
| dst->max = src->max; |
| |
| if (src->min < dst->min || !dst->nr) |
| dst->min = src->min; |
| |
| 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(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]; |
| |
| for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
| stats.contending_point[i] += pcs->contending_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(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)); |
| memset(class->contending_point, 0, sizeof(class->contending_point)); |
| } |
| |
| static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
| { |
| return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; |
| } |
| |
| static void put_lock_stats(struct lock_class_stats *stats) |
| { |
| put_cpu_var(cpu_lock_stats); |
| } |
| |
| static void lock_release_holdtime(struct held_lock *hlock) |
| { |
| struct lock_class_stats *stats; |
| u64 holdtime; |
| |
| if (!lock_stat) |
| return; |
| |
| holdtime = lockstat_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 |
| # define RECLAIM_VERBOSE 1 |
| #else |
| # define HARDIRQ_VERBOSE 0 |
| # define SOFTIRQ_VERBOSE 0 |
| # define RECLAIM_VERBOSE 0 |
| #endif |
| |
| #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_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); |
| |
| /* |
| * Some daft arches put -1 at the end to indicate its a full trace. |
| * |
| * <rant> this is buggy anyway, since it takes a whole extra entry so a |
| * complete trace that maxes out the entries provided will be reported |
| * as incomplete, friggin useless </rant> |
| */ |
| if (trace->nr_entries != 0 && |
| trace->entries[trace->nr_entries-1] == ULONG_MAX) |
| trace->nr_entries--; |
| |
| trace->max_entries = trace->nr_entries; |
| |
| nr_stack_trace_entries += trace->nr_entries; |
| |
| if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { |
| 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; |
| |
| #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 const char *lock_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: |
| */ |
| DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
| #endif |
| |
| /* |
| * Locking printouts: |
| */ |
| |
| #define __USAGE(__STATE) \ |
| [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
| [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ |
| [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ |
| [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", |
| |
| static const char *usage_str[] = |
| { |
| #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| [LOCK_USED] = "INITIAL USE", |
| }; |
| |
| const char * __get_key_name(struct lockdep_subclass_key *key, char *str) |
| { |
| return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
| } |
| |
| static inline unsigned long lock_flag(enum lock_usage_bit bit) |
| { |
| return 1UL << bit; |
| } |
| |
| static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
| { |
| char c = '.'; |
| |
| if (class->usage_mask & lock_flag(bit + 2)) |
| c = '+'; |
| if (class->usage_mask & lock_flag(bit)) { |
| c = '-'; |
| if (class->usage_mask & lock_flag(bit + 2)) |
| c = '?'; |
| } |
| |
| return c; |
| } |
| |
| void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
| { |
| int i = 0; |
| |
| #define LOCKDEP_STATE(__STATE) \ |
| usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ |
| usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| |
| usage[i] = '\0'; |
| } |
| |
| static void __print_lock_name(struct lock_class *class) |
| { |
| char str[KSYM_NAME_LEN]; |
| const char *name; |
| |
| 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); |
| } |
| } |
| |
| static void print_lock_name(struct lock_class *class) |
| { |
| char usage[LOCK_USAGE_CHARS]; |
| |
| get_usage_chars(class, usage); |
| |
| printk(" ("); |
| __print_lock_name(class); |
| printk("){%s}", usage); |
| } |
| |
| 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_kernel_ident(void) |
| { |
| printk("%s %.*s %s\n", init_utsname()->release, |
| (int)strcspn(init_utsname()->version, " "), |
| init_utsname()->version, |
| print_tainted()); |
| } |
| |
| 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; |
| |
| /* |
| * static variable? |
| */ |
| if ((addr >= start) && (addr < end)) |
| return 1; |
| |
| if (arch_is_kernel_data(addr)) |
| return 1; |
| |
| /* |
| * in-kernel percpu var? |
| */ |
| if (is_kernel_percpu_address(addr)) |
| return 1; |
| |
| /* |
| * module static or percpu var? |
| */ |
| return is_module_address(addr) || is_module_percpu_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; |
| lock_init_error = lock->name; |
| save_stack_trace(&lockdep_init_trace); |
| } |
| #endif |
| |
| if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
| debug_locks_off(); |
| printk(KERN_ERR |
| "BUG: looking up invalid subclass: %u\n", subclass); |
| printk(KERN_ERR |
| "turning off the locking correctness validator.\n"); |
| dump_stack(); |
| return NULL; |
| } |
| |
| /* |
| * 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) { |
| /* |
| * Huh! same key, different name? Did someone trample |
| * on some memory? We're most confused. |
| */ |
| 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)) |
| goto out_set_class_cache; |
| |
| /* |
| * 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"); |
| dump_stack(); |
| 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); |
| |
| out_set_class_cache: |
| if (!subclass || force) |
| lock->class_cache[0] = class; |
| else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
| lock->class_cache[subclass] = class; |
| |
| /* |
| * Hash collision, did we smoke some? We found a class with a matching |
| * hash but the subclass -- which is hashed in -- didn't match. |
| */ |
| 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"); |
| dump_stack(); |
| 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 stack_trace *trace) |
| { |
| 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; |
| entry->trace = *trace; |
| /* |
| * 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; |
| } |
| |
| /* |
| * For good efficiency of modular, we use power of 2 |
| */ |
| #define MAX_CIRCULAR_QUEUE_SIZE 4096UL |
| #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
| |
| /* |
| * The circular_queue and helpers is used to implement the |
| * breadth-first search(BFS)algorithem, by which we can build |
| * the shortest path from the next lock to be acquired to the |
| * previous held lock if there is a circular between them. |
| */ |
| struct circular_queue { |
| unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; |
| unsigned int front, rear; |
| }; |
| |
| static struct circular_queue lock_cq; |
| |
| unsigned int max_bfs_queue_depth; |
| |
| static unsigned int lockdep_dependency_gen_id; |
| |
| static inline void __cq_init(struct circular_queue *cq) |
| { |
| cq->front = cq->rear = 0; |
| lockdep_dependency_gen_id++; |
| } |
| |
| static inline int __cq_empty(struct circular_queue *cq) |
| { |
| return (cq->front == cq->rear); |
| } |
| |
| static inline int __cq_full(struct circular_queue *cq) |
| { |
| return ((cq->rear + 1) & CQ_MASK) == cq->front; |
| } |
| |
| static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) |
| { |
| if (__cq_full(cq)) |
| return -1; |
| |
| cq->element[cq->rear] = elem; |
| cq->rear = (cq->rear + 1) & CQ_MASK; |
| return 0; |
| } |
| |
| static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) |
| { |
| if (__cq_empty(cq)) |
| return -1; |
| |
| *elem = cq->element[cq->front]; |
| cq->front = (cq->front + 1) & CQ_MASK; |
| return 0; |
| } |
| |
| static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) |
| { |
| return (cq->rear - cq->front) & CQ_MASK; |
| } |
| |
| static inline void mark_lock_accessed(struct lock_list *lock, |
| struct lock_list *parent) |
| { |
| unsigned long nr; |
| |
| nr = lock - list_entries; |
| WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
| lock->parent = parent; |
| lock->class->dep_gen_id = lockdep_dependency_gen_id; |
| } |
| |
| static inline unsigned long lock_accessed(struct lock_list *lock) |
| { |
| unsigned long nr; |
| |
| nr = lock - list_entries; |
| WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
| return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
| } |
| |
| static inline struct lock_list *get_lock_parent(struct lock_list *child) |
| { |
| return child->parent; |
| } |
| |
| static inline int get_lock_depth(struct lock_list *child) |
| { |
| int depth = 0; |
| struct lock_list *parent; |
| |
| while ((parent = get_lock_parent(child))) { |
| child = parent; |
| depth++; |
| } |
| return depth; |
| } |
| |
| static int __bfs(struct lock_list *source_entry, |
| void *data, |
| int (*match)(struct lock_list *entry, void *data), |
| struct lock_list **target_entry, |
| int forward) |
| { |
| struct lock_list *entry; |
| struct list_head *head; |
| struct circular_queue *cq = &lock_cq; |
| int ret = 1; |
| |
| if (match(source_entry, data)) { |
| *target_entry = source_entry; |
| ret = 0; |
| goto exit; |
| } |
| |
| if (forward) |
| head = &source_entry->class->locks_after; |
| else |
| head = &source_entry->class->locks_before; |
| |
| if (list_empty(head)) |
| goto exit; |
| |
| __cq_init(cq); |
| __cq_enqueue(cq, (unsigned long)source_entry); |
| |
| while (!__cq_empty(cq)) { |
| struct lock_list *lock; |
| |
| __cq_dequeue(cq, (unsigned long *)&lock); |
| |
| if (!lock->class) { |
| ret = -2; |
| goto exit; |
| } |
| |
| if (forward) |
| head = &lock->class->locks_after; |
| else |
| head = &lock->class->locks_before; |
| |
| list_for_each_entry(entry, head, entry) { |
| if (!lock_accessed(entry)) { |
| unsigned int cq_depth; |
| mark_lock_accessed(entry, lock); |
| if (match(entry, data)) { |
| *target_entry = entry; |
| ret = 0; |
| goto exit; |
| } |
| |
| if (__cq_enqueue(cq, (unsigned long)entry)) { |
| ret = -1; |
| goto exit; |
| } |
| cq_depth = __cq_get_elem_count(cq); |
| if (max_bfs_queue_depth < cq_depth) |
| max_bfs_queue_depth = cq_depth; |
| } |
| } |
| } |
| exit: |
| return ret; |
| } |
| |
| static inline int __bfs_forwards(struct lock_list *src_entry, |
| void *data, |
| int (*match)(struct lock_list *entry, void *data), |
| struct lock_list **target_entry) |
| { |
| return __bfs(src_entry, data, match, target_entry, 1); |
| |
| } |
| |
| static inline int __bfs_backwards(struct lock_list *src_entry, |
| void *data, |
| int (*match)(struct lock_list *entry, void *data), |
| struct lock_list **target_entry) |
| { |
| return __bfs(src_entry, data, match, target_entry, 0); |
| |
| } |
| |
| /* |
| * Recursive, forwards-direction lock-dependency checking, used for |
| * both noncyclic checking and for hardirq-unsafe/softirq-unsafe |
| * checking. |
| */ |
| |
| /* |
| * 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, 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; |
| } |
| |
| static void |
| print_circular_lock_scenario(struct held_lock *src, |
| struct held_lock *tgt, |
| struct lock_list *prt) |
| { |
| struct lock_class *source = hlock_class(src); |
| struct lock_class *target = hlock_class(tgt); |
| struct lock_class *parent = prt->class; |
| |
| /* |
| * A direct locking problem where unsafe_class lock is taken |
| * directly by safe_class lock, then all we need to show |
| * is the deadlock scenario, as it is obvious that the |
| * unsafe lock is taken under the safe lock. |
| * |
| * But if there is a chain instead, where the safe lock takes |
| * an intermediate lock (middle_class) where this lock is |
| * not the same as the safe lock, then the lock chain is |
| * used to describe the problem. Otherwise we would need |
| * to show a different CPU case for each link in the chain |
| * from the safe_class lock to the unsafe_class lock. |
| */ |
| if (parent != source) { |
| printk("Chain exists of:\n "); |
| __print_lock_name(source); |
| printk(" --> "); |
| __print_lock_name(parent); |
| printk(" --> "); |
| __print_lock_name(target); |
| printk("\n\n"); |
| } |
| |
| printk(" Possible unsafe locking scenario:\n\n"); |
| printk(" CPU0 CPU1\n"); |
| printk(" ---- ----\n"); |
| printk(" lock("); |
| __print_lock_name(target); |
| printk(");\n"); |
| printk(" lock("); |
| __print_lock_name(parent); |
| printk(");\n"); |
| printk(" lock("); |
| __print_lock_name(target); |
| printk(");\n"); |
| printk(" lock("); |
| __print_lock_name(source); |
| printk(");\n"); |
| printk("\n *** DEADLOCK ***\n\n"); |
| } |
| |
| /* |
| * 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 held_lock *check_src, |
| struct held_lock *check_tgt) |
| { |
| struct task_struct *curr = current; |
| |
| if (debug_locks_silent) |
| return 0; |
| |
| printk("\n"); |
| printk("======================================================\n"); |
| printk("[ INFO: possible circular locking dependency detected ]\n"); |
| print_kernel_ident(); |
| printk("-------------------------------------------------------\n"); |
| printk("%s/%d is trying to acquire lock:\n", |
| curr->comm, task_pid_nr(curr)); |
| print_lock(check_src); |
| printk("\nbut task is already holding lock:\n"); |
| print_lock(check_tgt); |
| 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 inline int class_equal(struct lock_list *entry, void *data) |
| { |
| return entry->class == data; |
| } |
| |
| static noinline int print_circular_bug(struct lock_list *this, |
| struct lock_list *target, |
| struct held_lock *check_src, |
| struct held_lock *check_tgt) |
| { |
| struct task_struct *curr = current; |
| struct lock_list *parent; |
| struct lock_list *first_parent; |
| int depth; |
| |
| if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| return 0; |
| |
| if (!save_trace(&this->trace)) |
| return 0; |
| |
| depth = get_lock_depth(target); |
| |
| print_circular_bug_header(target, depth, check_src, check_tgt); |
| |
| parent = get_lock_parent(target); |
| first_parent = parent; |
| |
| while (parent) { |
| print_circular_bug_entry(parent, --depth); |
| parent = get_lock_parent(parent); |
| } |
| |
| printk("\nother info that might help us debug this:\n\n"); |
| print_circular_lock_scenario(check_src, check_tgt, |
| first_parent); |
| |
| lockdep_print_held_locks(curr); |
| |
| printk("\nstack backtrace:\n"); |
| dump_stack(); |
| |
| return 0; |
| } |
| |
| static noinline int print_bfs_bug(int ret) |
| { |
| if (!debug_locks_off_graph_unlock()) |
| return 0; |
| |
| /* |
| * Breadth-first-search failed, graph got corrupted? |
| */ |
| WARN(1, "lockdep bfs error:%d\n", ret); |
| |
| return 0; |
| } |
| |
| static int noop_count(struct lock_list *entry, void *data) |
| { |
| (*(unsigned long *)data)++; |
| return 0; |
| } |
| |
| unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
| { |
| unsigned long count = 0; |
| struct lock_list *uninitialized_var(target_entry); |
| |
| __bfs_forwards(this, (void *)&count, noop_count, &target_entry); |
| |
| return count; |
| } |
| unsigned long lockdep_count_forward_deps(struct lock_class *class) |
| { |
| unsigned long ret, flags; |
| struct lock_list this; |
| |
| this.parent = NULL; |
| this.class = class; |
| |
| local_irq_save(flags); |
| arch_spin_lock(&lockdep_lock); |
| ret = __lockdep_count_forward_deps(&this); |
| arch_spin_unlock(&lockdep_lock); |
| local_irq_restore(flags); |
| |
| return ret; |
| } |
| |
| unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
| { |
| unsigned long count = 0; |
| struct lock_list *uninitialized_var(target_entry); |
| |
| __bfs_backwards(this, (void *)&count, noop_count, &target_entry); |
| |
| return count; |
| } |
| |
| unsigned long lockdep_count_backward_deps(struct lock_class *class) |
| { |
| unsigned long ret, flags; |
| struct lock_list this; |
| |
| this.parent = NULL; |
| this.class = class; |
| |
| local_irq_save(flags); |
| arch_spin_lock(&lockdep_lock); |
| ret = __lockdep_count_backward_deps(&this); |
| arch_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_list *root, struct lock_class *target, |
| struct lock_list **target_entry) |
| { |
| int result; |
| |
| debug_atomic_inc(nr_cyclic_checks); |
| |
| result = __bfs_forwards(root, target, class_equal, target_entry); |
| |
| return result; |
| } |
| |
| #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 inline int usage_match(struct lock_list *entry, void *bit) |
| { |
| return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); |
| } |
| |
| |
| |
| /* |
| * Find a node in the forwards-direction dependency sub-graph starting |
| * at @root->class that matches @bit. |
| * |
| * Return 0 if such a node exists in the subgraph, and put that node |
| * into *@target_entry. |
| * |
| * Return 1 otherwise and keep *@target_entry unchanged. |
| * Return <0 on error. |
| */ |
| static int |
| find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, |
| struct lock_list **target_entry) |
| { |
| int result; |
| |
| debug_atomic_inc(nr_find_usage_forwards_checks); |
| |
| result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); |
| |
| return result; |
| } |
| |
| /* |
| * Find a node in the backwards-direction dependency sub-graph starting |
| * at @root->class that matches @bit. |
| * |
| * Return 0 if such a node exists in the subgraph, and put that node |
| * into *@target_entry. |
| * |
| * Return 1 otherwise and keep *@target_entry unchanged. |
| * Return <0 on error. |
| */ |
| static int |
| find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, |
| struct lock_list **target_entry) |
| { |
| int result; |
| |
| debug_atomic_inc(nr_find_usage_backwards_checks); |
| |
| result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); |
| |
| return result; |
| } |
| |
| 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 the shortest lock dependencies from @start to @end in reverse order: |
| */ |
| static void __used |
| print_shortest_lock_dependencies(struct lock_list *leaf, |
| struct lock_list *root) |
| { |
| struct lock_list *entry = leaf; |
| int depth; |
| |
| /*compute depth from generated tree by BFS*/ |
| depth = get_lock_depth(leaf); |
| |
| do { |
| print_lock_class_header(entry->class, depth); |
| printk("%*s ... acquired at:\n", depth, ""); |
| print_stack_trace(&entry->trace, 2); |
| printk("\n"); |
| |
| if (depth == 0 && (entry != root)) { |
| printk("lockdep:%s bad path found in chain graph\n", __func__); |
| break; |
| } |
| |
| entry = get_lock_parent(entry); |
| depth--; |
| } while (entry && (depth >= 0)); |
| |
| return; |
| } |
| |
| static void |
| print_irq_lock_scenario(struct lock_list *safe_entry, |
| struct lock_list *unsafe_entry, |
| struct lock_class *prev_class, |
| struct lock_class *next_class) |
| { |
| struct lock_class *safe_class = safe_entry->class; |
| struct lock_class *unsafe_class = unsafe_entry->class; |
| struct lock_class *middle_class = prev_class; |
| |
| if (middle_class == safe_class) |
| middle_class = next_class; |
| |
| /* |
| * A direct locking problem where unsafe_class lock is taken |
| * directly by safe_class lock, then all we need to show |
| * is the deadlock scenario, as it is obvious that the |
| * unsafe lock is taken under the safe lock. |
| * |
| * But if there is a chain instead, where the safe lock takes |
| * an intermediate lock (middle_class) where this lock is |
| * not the same as the safe lock, then the lock chain is |
| * used to describe the problem. Otherwise we would need |
| * to show a different CPU case for each link in the chain |
| * from the safe_class lock to the unsafe_class lock. |
| */ |
| if (middle_class != unsafe_class) { |
| printk("Chain exists of:\n "); |
| __print_lock_name(safe_class); |
| printk(" --> "); |
| __print_lock_name(middle_class); |
| printk(" --> "); |
| __print_lock_name(unsafe_class); |
| printk("\n\n"); |
| } |
| |
| printk(" Possible interrupt unsafe locking scenario:\n\n"); |
| printk(" CPU0 CPU1\n"); |
| printk(" ---- ----\n"); |
| printk(" lock("); |
| __print_lock_name(unsafe_class); |
| printk(");\n"); |
| printk(" local_irq_disable();\n"); |
| printk(" lock("); |
| __print_lock_name(safe_class); |
| printk(");\n"); |
| printk(" lock("); |
| __print_lock_name(middle_class); |
| printk(");\n"); |
| printk(" <Interrupt>\n"); |
| printk(" lock("); |
| __print_lock_name(safe_class); |
| printk(");\n"); |
| printk("\n *** DEADLOCK ***\n\n"); |
| } |
| |
| static int |
| print_bad_irq_dependency(struct task_struct *curr, |
| struct lock_list *prev_root, |
| struct lock_list *next_root, |
| struct lock_list *backwards_entry, |
| struct lock_list *forwards_entry, |
| 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"); |
| printk("======================================================\n"); |
| printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", |
| irqclass, irqclass); |
| print_kernel_ident(); |
| 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_entry->class); |
| printk("\n... which became %s-irq-safe at:\n", irqclass); |
| |
| print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); |
| |
| printk("\nto a %s-irq-unsafe lock:\n", irqclass); |
| print_lock_name(forwards_entry->class); |
| printk("\n... which became %s-irq-unsafe at:\n", irqclass); |
| printk("..."); |
| |
| print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); |
| |
| printk("\nother info that might help us debug this:\n\n"); |
| print_irq_lock_scenario(backwards_entry, forwards_entry, |
| hlock_class(prev), hlock_class(next)); |
| |
| lockdep_print_held_locks(curr); |
| |
| printk("\nthe dependencies between %s-irq-safe lock", irqclass); |
| printk(" and the holding lock:\n"); |
| if (!save_trace(&prev_root->trace)) |
| return 0; |
| print_shortest_lock_dependencies(backwards_entry, prev_root); |
| |
| printk("\nthe dependencies between the lock to be acquired"); |
| printk(" and %s-irq-unsafe lock:\n", irqclass); |
| if (!save_trace(&next_root->trace)) |
| return 0; |
| print_shortest_lock_dependencies(forwards_entry, next_root); |
| |
| 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; |
| struct lock_list this, that; |
| struct lock_list *uninitialized_var(target_entry); |
| struct lock_list *uninitialized_var(target_entry1); |
| |
| this.parent = NULL; |
| |
| this.class = hlock_class(prev); |
| ret = find_usage_backwards(&this, bit_backwards, &target_entry); |
| if (ret < 0) |
| return print_bfs_bug(ret); |
| if (ret == 1) |
| return ret; |
| |
| that.parent = NULL; |
| that.class = hlock_class(next); |
| ret = find_usage_forwards(&that, bit_forwards, &target_entry1); |
| if (ret < 0) |
| return print_bfs_bug(ret); |
| if (ret == 1) |
| return ret; |
| |
| return print_bad_irq_dependency(curr, &this, &that, |
| target_entry, target_entry1, |
| prev, next, |
| bit_backwards, bit_forwards, irqclass); |
| } |
| |
| static const char *state_names[] = { |
| #define LOCKDEP_STATE(__STATE) \ |
| __stringify(__STATE), |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| }; |
| |
| static const char *state_rnames[] = { |
| #define LOCKDEP_STATE(__STATE) \ |
| __stringify(__STATE)"-READ", |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| }; |
| |
| static inline const char *state_name(enum lock_usage_bit bit) |
| { |
| return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; |
| } |
| |
| static int exclusive_bit(int new_bit) |
| { |
| /* |
| * USED_IN |
| * USED_IN_READ |
| * ENABLED |
| * ENABLED_READ |
| * |
| * bit 0 - write/read |
| * bit 1 - used_in/enabled |
| * bit 2+ state |
| */ |
| |
| int state = new_bit & ~3; |
| int dir = new_bit & 2; |
| |
| /* |
| * keep state, bit flip the direction and strip read. |
| */ |
| return state | (dir ^ 2); |
| } |
| |
| static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
| struct held_lock *next, enum lock_usage_bit bit) |
| { |
| /* |
| * 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, bit, |
| exclusive_bit(bit), state_name(bit))) |
| return 0; |
| |
| bit++; /* _READ */ |
| |
| /* |
| * 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, bit, |
| exclusive_bit(bit), state_name(bit))) |
| return 0; |
| |
| return 1; |
| } |
| |
| static int |
| check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
| struct held_lock *next) |
| { |
| #define LOCKDEP_STATE(__STATE) \ |
| if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ |
| return 0; |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| |
| 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 void |
| print_deadlock_scenario(struct held_lock *nxt, |
| struct held_lock *prv) |
| { |
| struct lock_class *next = hlock_class(nxt); |
| struct lock_class *prev = hlock_class(prv); |
| |
| printk(" Possible unsafe locking scenario:\n\n"); |
| printk(" CPU0\n"); |
| printk(" ----\n"); |
| printk(" lock("); |
| __print_lock_name(prev); |
| printk(");\n"); |
| printk(" lock("); |
| __print_lock_name(next); |
| printk(");\n"); |
| printk("\n *** DEADLOCK ***\n\n"); |
| printk(" May be due to missing lock nesting notation\n\n"); |
| } |
| |
| 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"); |
| printk("=============================================\n"); |
| printk("[ INFO: possible recursive locking detected ]\n"); |
| print_kernel_ident(); |
| 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"); |
| print_deadlock_scenario(next, prev); |
| 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, int trylock_loop) |
| { |
| struct lock_list *entry; |
| int ret; |
| struct lock_list this; |
| struct lock_list *uninitialized_var(target_entry); |
| /* |
| * Static variable, serialized by the graph_lock(). |
| * |
| * We use this static variable to save the stack trace in case |
| * we call into this function multiple times due to encountering |
| * trylocks in the held lock stack. |
| */ |
| static struct stack_trace trace; |
| |
| /* |
| * 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: |
| */ |
| this.class = hlock_class(next); |
| this.parent = NULL; |
| ret = check_noncircular(&this, hlock_class(prev), &target_entry); |
| if (unlikely(!ret)) |
| return print_circular_bug(&this, target_entry, next, prev); |
| else if (unlikely(ret < 0)) |
| return print_bfs_bug(ret); |
| |
| 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; |
| } |
| } |
| |
| if (!trylock_loop && !save_trace(&trace)) |
| return 0; |
| |
| /* |
| * 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, &trace); |
| |
| if (!ret) |
| return 0; |
| |
| ret = add_lock_to_list(hlock_class(next), hlock_class(prev), |
| &hlock_class(next)->locks_before, |
| next->acquire_ip, distance, &trace); |
| 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; |
| int trylock_loop = 0; |
| 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, trylock_loop)) |
| 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; |
| trylock_loop = 1; |
| } |
| return 1; |
| out_bug: |
| if (!debug_locks_off_graph_unlock()) |
| return 0; |
| |
| /* |
| * Clearly we all shouldn't be here, but since we made it we |
| * can reliable say we messed up our state. See the above two |
| * gotos for reasons why we could possibly end up here. |
| */ |
| 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; |
| |
| /* |
| * We might need to take the graph lock, ensure we've got IRQs |
| * disabled to make this an IRQ-safe lock.. for recursion reasons |
| * lockdep won't complain about its own locking errors. |
| */ |
| 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"); |
| dump_stack(); |
| 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; |
| if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { |
| chain->base = nr_chain_hlocks; |
| nr_chain_hlocks += chain->depth; |
| 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(); |
| /* |
| * We got mighty confused, our chain keys don't match |
| * with what we expect, someone trample on our task state? |
| */ |
| WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
| curr->lockdep_depth, i, |
| (unsigned long long)chain_key, |
| (unsigned long long)hlock->prev_chain_key); |
| return; |
| } |
| id = hlock->class_idx - 1; |
| /* |
| * Whoops ran out of static storage again? |
| */ |
| 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(); |
| /* |
| * More smoking hash instead of calculating it, damn see these |
| * numbers float.. I bet that a pink elephant stepped on my memory. |
| */ |
| WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
| curr->lockdep_depth, i, |
| (unsigned long long)chain_key, |
| (unsigned long long)curr->curr_chain_key); |
| } |
| #endif |
| } |
| |
| static void |
| print_usage_bug_scenario(struct held_lock *lock) |
| { |
| struct lock_class *class = hlock_class(lock); |
| |
| printk(" Possible unsafe locking scenario:\n\n"); |
| printk(" CPU0\n"); |
| printk(" ----\n"); |
| printk(" lock("); |
| __print_lock_name(class); |
| printk(");\n"); |
| printk(" <Interrupt>\n"); |
| printk(" lock("); |
| __print_lock_name(class); |
| printk(");\n"); |
| printk("\n *** DEADLOCK ***\n\n"); |
| } |
| |
| 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"); |
| printk("=================================\n"); |
| printk("[ INFO: inconsistent lock state ]\n"); |
| print_kernel_ident(); |
| 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"); |
| print_usage_bug_scenario(this); |
| |
| 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_list *root, struct lock_list *other, |
| struct held_lock *this, int forwards, |
| const char *irqclass) |
| { |
| struct lock_list *entry = other; |
| struct lock_list *middle = NULL; |
| int depth; |
| |
| if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| return 0; |
| |
| printk("\n"); |
| printk("=========================================================\n"); |
| printk("[ INFO: possible irq lock inversion dependency detected ]\n"); |
| print_kernel_ident(); |
| 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-unsafe lock in the past:\n", irqclass); |
| else |
| printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
| print_lock_name(other->class); |
| printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
| |
| printk("\nother info that might help us debug this:\n"); |
| |
| /* Find a middle lock (if one exists) */ |
| depth = get_lock_depth(other); |
| do { |
| if (depth == 0 && (entry != root)) { |
| printk("lockdep:%s bad path found in chain graph\n", __func__); |
| break; |
| } |
| middle = entry; |
| entry = get_lock_parent(entry); |
| depth--; |
| } while (entry && entry != root && (depth >= 0)); |
| if (forwards) |
| print_irq_lock_scenario(root, other, |
| middle ? middle->class : root->class, other->class); |
| else |
| print_irq_lock_scenario(other, root, |
| middle ? middle->class : other->class, root->class); |
| |
| lockdep_print_held_locks(curr); |
| |
| printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
| if (!save_trace(&root->trace)) |
| return 0; |
| print_shortest_lock_dependencies(other, root); |
| |
| 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; |
| struct lock_list root; |
| struct lock_list *uninitialized_var(target_entry); |
| |
| root.parent = NULL; |
| root.class = hlock_class(this); |
| ret = find_usage_forwards(&root, bit, &target_entry); |
| if (ret < 0) |
| return print_bfs_bug(ret); |
| if (ret == 1) |
| return ret; |
| |
| return print_irq_inversion_bug(curr, &root, target_entry, |
| 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; |
| struct lock_list root; |
| struct lock_list *uninitialized_var(target_entry); |
| |
| root.parent = NULL; |
| root.class = hlock_class(this); |
| ret = find_usage_backwards(&root, bit, &target_entry); |
| if (ret < 0) |
| return print_bfs_bug(ret); |
| if (ret == 1) |
| return ret; |
| |
| return print_irq_inversion_bug(curr, &root, target_entry, |
| 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; |
| } |
| |
| static int RECLAIM_FS_verbose(struct lock_class *class) |
| { |
| #if RECLAIM_VERBOSE |
| return class_filter(class); |
| #endif |
| return 0; |
| } |
| |
| #define STRICT_READ_CHECKS 1 |
| |
| static int (*state_verbose_f[])(struct lock_class *class) = { |
| #define LOCKDEP_STATE(__STATE) \ |
| __STATE##_verbose, |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| }; |
| |
| static inline int state_verbose(enum lock_usage_bit bit, |
| struct lock_class *class) |
| { |
| return state_verbose_f[bit >> 2](class); |
| } |
| |
| typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
| enum lock_usage_bit bit, const char *name); |
| |
| static int |
| mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
| enum lock_usage_bit new_bit) |
| { |
| int excl_bit = exclusive_bit(new_bit); |
| int read = new_bit & 1; |
| int dir = new_bit & 2; |
| |
| /* |
| * mark USED_IN has to look forwards -- to ensure no dependency |
| * has ENABLED state, which would allow recursion deadlocks. |
| * |
| * mark ENABLED has to look backwards -- to ensure no dependee |
| * has USED_IN state, which, again, would allow recursion deadlocks. |
| */ |
| check_usage_f usage = dir ? |
| check_usage_backwards : check_usage_forwards; |
| |
| /* |
| * Validate that this particular lock does not have conflicting |
| * usage states. |
| */ |
| if (!valid_state(curr, this, new_bit, excl_bit)) |
| return 0; |
| |
| /* |
| * Validate that the lock dependencies don't have conflicting usage |
| * states. |
| */ |
| if ((!read || !dir || STRICT_READ_CHECKS) && |
| !usage(curr, this, excl_bit, state_name(new_bit & ~1))) |
| return 0; |
| |
| /* |
| * Check for read in write conflicts |
| */ |
| if (!read) { |
| if (!valid_state(curr, this, new_bit, excl_bit + 1)) |
| return 0; |
| |
| if (STRICT_READ_CHECKS && |
| !usage(curr, this, excl_bit + 1, |
| state_name(new_bit + 1))) |
| return 0; |
| } |
| |
| if (state_verbose(new_bit, hlock_class(this))) |
| return 2; |
| |
| return 1; |
| } |
| |
| enum mark_type { |
| #define LOCKDEP_STATE(__STATE) __STATE, |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| }; |
| |
| /* |
| * Mark all held locks with a usage bit: |
| */ |
| static int |
| mark_held_locks(struct task_struct *curr, enum mark_type mark) |
| { |
| 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; |
| |
| usage_bit = 2 + (mark << 2); /* ENABLED */ |
| if (hlock->read) |
| usage_bit += 1; /* READ */ |
| |
| BUG_ON(usage_bit >= LOCK_USAGE_STATES); |
| |
| if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys) |
| continue; |
| |
| if (!mark_lock(curr, hlock, usage_bit)) |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| /* |
| * Hardirqs will be enabled: |
| */ |
| static void __trace_hardirqs_on_caller(unsigned long ip) |
| { |
| struct task_struct *curr = current; |
| |
| /* we'll do an OFF -> ON transition: */ |
| curr->hardirqs_enabled = 1; |
| |
| /* |
| * We are going to turn hardirqs on, so set the |
| * usage bit for all held locks: |
| */ |
| if (!mark_held_locks(curr, HARDIRQ)) |
| 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, SOFTIRQ)) |
| return; |
| |
| curr->hardirq_enable_ip = ip; |
| curr->hardirq_enable_event = ++curr->irq_events; |
| debug_atomic_inc(hardirqs_on_events); |
| } |
| |
| void trace_hardirqs_on_caller(unsigned long ip) |
| { |
| time_hardirqs_on(CALLER_ADDR0, ip); |
| |
| if (unlikely(!debug_locks || current->lockdep_recursion)) |
| return; |
| |
| if (unlikely(current->hardirqs_enabled)) { |
| /* |
| * Neither irq nor preemption are disabled here |
| * so this is racy by nature but losing one hit |
| * in a stat is not a big deal. |
| */ |
| __debug_atomic_inc(redundant_hardirqs_on); |
| return; |
| } |
| |
| /* |
| * We're enabling irqs and according to our state above irqs weren't |
| * already enabled, yet we find the hardware thinks they are in fact |
| * enabled.. someone messed up their IRQ state tracing. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| return; |
| |
| /* |
| * See the fine text that goes along with this variable definition. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) |
| return; |
| |
| /* |
| * Can't allow enabling interrupts while in an interrupt handler, |
| * that's general bad form and such. Recursion, limited stack etc.. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) |
| return; |
| |
| current->lockdep_recursion = 1; |
| __trace_hardirqs_on_caller(ip); |
| current->lockdep_recursion = 0; |
| } |
| 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 ip) |
| { |
| struct task_struct *curr = current; |
| |
| time_hardirqs_off(CALLER_ADDR0, ip); |
| |
| if (unlikely(!debug_locks || current->lockdep_recursion)) |
| return; |
| |
| /* |
| * So we're supposed to get called after you mask local IRQs, but for |
| * some reason the hardware doesn't quite think you did a proper job. |
| */ |
| 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 = 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 || current->lockdep_recursion)) |
| return; |
| |
| /* |
| * We fancy IRQs being disabled here, see softirq.c, avoids |
| * funny state and nesting things. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| return; |
| |
| if (curr->softirqs_enabled) { |
| debug_atomic_inc(redundant_softirqs_on); |
| return; |
| } |
| |
| current->lockdep_recursion = 1; |
| /* |
| * 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, SOFTIRQ); |
| current->lockdep_recursion = 0; |
| } |
| |
| /* |
| * Softirqs were disabled: |
| */ |
| void trace_softirqs_off(unsigned long ip) |
| { |
| struct task_struct *curr = current; |
| |
| if (unlikely(!debug_locks || current->lockdep_recursion)) |
| return; |
| |
| /* |
| * We fancy IRQs being disabled here, see softirq.c |
| */ |
| 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); |
| /* |
| * Whoops, we wanted softirqs off, so why aren't they? |
| */ |
| DEBUG_LOCKS_WARN_ON(!softirq_count()); |
| } else |
| debug_atomic_inc(redundant_softirqs_off); |
| } |
| |
| static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) |
| { |
| struct task_struct *curr = current; |
| |
| if (unlikely(!debug_locks)) |
| return; |
| |
| /* no reclaim without waiting on it */ |
| if (!(gfp_mask & __GFP_WAIT)) |
| return; |
| |
| /* this guy won't enter reclaim */ |
| if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) |
| return; |
| |
| /* We're only interested __GFP_FS allocations for now */ |
| if (!(gfp_mask & __GFP_FS)) |
| return; |
| |
| /* |
| * Oi! Can't be having __GFP_FS allocations with IRQs disabled. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) |
| return; |
| |
| mark_held_locks(curr, RECLAIM_FS); |
| } |
| |
| static void check_flags(unsigned long flags); |
| |
| void lockdep_trace_alloc(gfp_t gfp_mask) |
| { |
| unsigned long flags; |
| |
| if (unlikely(current->lockdep_recursion)) |
| return; |
| |
| raw_local_irq_save(flags); |
| check_flags(flags); |
| current->lockdep_recursion = 1; |
| __lockdep_trace_alloc(gfp_mask, flags); |
| current->lockdep_recursion = 0; |
| raw_local_irq_restore(flags); |
| } |
| |
| 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_HARDIRQ_READ)) |
| return 0; |
| if (curr->softirqs_enabled) |
| if (!mark_lock(curr, hlock, |
| LOCK_ENABLED_SOFTIRQ_READ)) |
| return 0; |
| } else { |
| if (!mark_lock(curr, hlock, |
| LOCK_ENABLED_HARDIRQ)) |
| return 0; |
| if (curr->softirqs_enabled) |
| if (!mark_lock(curr, hlock, |
| LOCK_ENABLED_SOFTIRQ)) |
| return 0; |
| } |
| } |
| |
| /* |
| * We reuse the irq context infrastructure more broadly as a general |
| * context checking code. This tests GFP_FS recursion (a lock taken |
| * during reclaim for a GFP_FS allocation is held over a GFP_FS |
| * allocation). |
| */ |
| if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { |
| if (hlock->read) { |
| if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) |
| return 0; |
| } else { |
| if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) |
| 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 /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
| |
| static inline |
| int mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
| enum lock_usage_bit new_bit) |
| { |
| WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ |
| 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; |
| } |
| |
| void lockdep_trace_alloc(gfp_t gfp_mask) |
| { |
| } |
| |
| #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
| |
| /* |
| * 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 didn't 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) { |
| #define LOCKDEP_STATE(__STATE) \ |
| case LOCK_USED_IN_##__STATE: \ |
| case LOCK_USED_IN_##__STATE##_READ: \ |
| case LOCK_ENABLED_##__STATE: \ |
| case LOCK_ENABLED_##__STATE##_READ: |
| #include "lockdep_states.h" |
| #undef LOCKDEP_STATE |
| 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) |
| { |
| int i; |
| |
| kmemcheck_mark_initialized(lock, sizeof(*lock)); |
| |
| for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
| lock->class_cache[i] = NULL; |
| |
| #ifdef CONFIG_LOCK_STAT |
| lock->cpu = raw_smp_processor_id(); |
| #endif |
| |
| /* |
| * Can't be having no nameless bastards around this place! |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!name)) { |
| lock->name = "NULL"; |
| return; |
| } |
| |
| lock->name = name; |
| |
| /* |
| * No key, no joy, we need to hash something. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!key)) |
| return; |
| /* |
| * Sanity check, the lock-class key must be persistent: |
| */ |
| if (!static_obj(key)) { |
| printk("BUG: key %p not in .data!\n", key); |
| /* |
| * What it says above ^^^^^, I suggest you read it. |
| */ |
| DEBUG_LOCKS_WARN_ON(1); |
| return; |
| } |
| lock->key = key; |
| |
| if (unlikely(!debug_locks)) |
| return; |
| |
| if (subclass) |
| register_lock_class(lock, subclass, 1); |
| } |
| EXPORT_SYMBOL_GPL(lockdep_init_map); |
| |
| struct lock_class_key __lockdep_no_validate__; |
| |
| /* |
| * 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, |
| int references) |
| { |
| struct task_struct *curr = current; |
| struct lock_class *class = NULL; |
| struct held_lock *hlock; |
| unsigned int depth, id; |
| int chain_head = 0; |
| int class_idx; |
| u64 chain_key; |
| |
| if (!prove_locking) |
| check = 1; |
| |
| if (unlikely(!debug_locks)) |
| return 0; |
| |
| /* |
| * Lockdep should run with IRQs disabled, otherwise we could |
| * get an interrupt which would want to take locks, which would |
| * end up in lockdep and have you got a head-ache already? |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| return 0; |
| |
| if (lock->key == &__lockdep_no_validate__) |
| check = 1; |
| |
| if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
| class = lock->class_cache[subclass]; |
| /* |
| * Not cached? |
| */ |
| if (unlikely(!class)) { |
| class = register_lock_class(lock, subclass, 0); |
| if (!class) |
| return 0; |
| } |
| 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; |
| /* |
| * Ran out of static storage for our per-task lock stack again have we? |
| */ |
| if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
| return 0; |
| |
| class_idx = class - lock_classes + 1; |
| |
| if (depth) { |
| hlock = curr->held_locks + depth - 1; |
| if (hlock->class_idx == class_idx && nest_lock) { |
| if (hlock->references) |
| hlock->references++; |
| else |
| hlock->references = 2; |
| |
| return 1; |
| } |
| } |
| |
| hlock = curr->held_locks + depth; |
| /* |
| * Plain impossible, we just registered it and checked it weren't no |
| * NULL like.. I bet this mushroom I ate was good! |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!class)) |
| return 0; |
| hlock->class_idx = class_idx; |
| 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; |
| hlock->references = references; |
| #ifdef CONFIG_LOCK_STAT |
| hlock->waittime_stamp = 0; |
| hlock->holdtime_stamp = lockstat_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; |
| /* |
| * Whoops, we did it again.. ran straight out of our static allocation. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
| return 0; |
| |
| chain_key = curr->curr_chain_key; |
| if (!depth) { |
| /* |
| * How can we have a chain hash when we ain't got no keys?! |
| */ |
| 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"); |
| dump_stack(); |
| 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"); |
| printk("=====================================\n"); |
| printk("[ BUG: bad unlock balance detected! ]\n"); |
| print_kernel_ident(); |
| 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; |
| /* |
| * Lockdep should run with IRQs disabled, recursion, head-ache, etc.. |
| */ |
| 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 match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) |
| { |
| if (hlock->instance == lock) |
| return 1; |
| |
| if (hlock->references) { |
| struct lock_class *class = lock->class_cache[0]; |
| |
| if (!class) |
| class = look_up_lock_class(lock, 0); |
| |
| /* |
| * If look_up_lock_class() failed to find a class, we're trying |
| * to test if we hold a lock that has never yet been acquired. |
| * Clearly if the lock hasn't been acquired _ever_, we're not |
| * holding it either, so report failure. |
| */ |
| if (!class) |
| return 0; |
| |
| /* |
| * References, but not a lock we're actually ref-counting? |
| * State got messed up, follow the sites that change ->references |
| * and try to make sense of it. |
| */ |
| if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
| return 0; |
| |
| if (hlock->class_idx == class - lock_classes + 1) |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| static int |
| __lock_set_class(struct lockdep_map *lock, const char *name, |
| struct lock_class_key *key, 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; |
| /* |
| * This function is about (re)setting the class of a held lock, |
| * yet we're not actually holding any locks. Naughty user! |
| */ |
| 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 (match_held_lock(hlock, lock)) |
| goto found_it; |
| prev_hlock = hlock; |
| } |
| return print_unlock_inbalance_bug(curr, lock, ip); |
| |
| found_it: |
| lockdep_init_map(lock, name, key, 0); |
| 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 |