litmus-rt.git - The LITMUS^RT kernel.

	Commit message (Expand)	Author	Age
*	move memory_read_from_buffer() from fs.h to string.h	Akinobu Mita	2008-07-24
*	zorro: use memory_read_from_buffer	akinobu.mita@gmail.com	2008-07-20
*	ZORRO: Replace deprecated __initcall with equivalent device_initcall.	Robert P. J. Day	2008-07-20
*	m68k: remove CVS keywords	Adrian Bunk	2008-07-20
*	zorro: use non-racy method for proc entries creation	Denis V. Lunev	2008-04-29
*	proc: switch /proc/bus/zorro/devices to seq_file interface	Alexey Dobriyan	2008-04-29
*	proc: remove proc_bus	Alexey Dobriyan	2008-04-29
*	Amiga zorro bus: Add missing zorro_device_remove()	Geert Uytterhoeven	2007-11-26
*	Convert files to UTF-8 and some cleanups	Jan Engelhardt	2007-10-19
*	zorro: Make sysfs config attribute read-only	Geert Uytterhoeven	2007-08-22
*	sysfs: add parameter "struct bin_attribute *" in .read/.write methods for sys...	Zhang Rui	2007-07-11
*	sysfs: kill unnecessary attribute->owner	Tejun Heo	2007-07-11
*	Amiga Zorro bus: kill resource_size_t warnings	Geert Uytterhoeven	2007-05-04
*	[PATCH] mark struct file_operations const 6	Arjan van de Ven	2007-02-12
*	[PATCH] struct path: convert zorro	Josef Sipek	2006-12-08
*	Remove obsolete #include <linux/config.h>	Jörn Engel	2006-06-30
*	[PATCH] amiga: fix driver_register() return handling, remove zorro_module_init()	Bjorn Helgaas	2006-03-25
*	[PATCH] Add zorro_bus_type probe and remove methods	Russell King	2006-01-13
*	[PATCH] m68k: zorro __user annotations	Al Viro	2006-01-12
*	[PATCH] fix missing includes	Tim Schmielau	2005-10-30
*	[PATCH] Driver Core: drivers/usb/input/aiptek.c - drivers/zorro/zorro-sysfs.c...	Yani Ioannou	2005-06-20
*	Linux-2.6.12-rc2v2.6.12-rc2	Linus Torvalds	2005-04-16

/* * 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 <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)) 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) { 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 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], usage[LOCK_USAGE_CHARS]; const char *name; get_usage_chars(class, usage); 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("){%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_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; /* * 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; 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"); 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); 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"); 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); 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); 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; } /* * 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=======================================================\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_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; 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); while (parent) { print_circular_bug_entry(parent, --depth); parent = get_lock_parent(parent); } printk("\nother info that might help us debug this:\n\n"); 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; 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 BFS generated tree\n", __func__); break; } entry = get_lock_parent(entry); depth--; } while (entry && (depth >= 0)); return; } 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======================================================\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_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"); 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 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, 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; 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"); 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; 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(); 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; 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(); 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 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_list *root, struct lock_list *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-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"); 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 (!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 ip) { struct task_struct *curr = current; time_hardirqs_on(CALLER_ADDR0, ip); if (unlikely(!debug_locks || current->lockdep_recursion)) return; if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) return; if (unlikely(curr->hardirqs_enabled)) { /* * Neither irq nor preemption are disabled here * so this is racy by nature but loosing one hit * in a stat is not a big deal. */ __debug_atomic_inc(redundant_hardirqs_on); return; } /* we'll do an OFF -> ON transition: */ curr->hardirqs_enabled = 1; 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, 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); } 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; 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)) 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, SOFTIRQ); } /* * 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 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; 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 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; } void lockdep_trace_alloc(gfp_t gfp_mask) { } #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) { #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) { lock->class_cache = NULL; #ifdef CONFIG_LOCK_STAT lock->cpu = raw_smp_processor_id(); #endif if (DEBUG_LOCKS_WARN_ON(!name)) { lock->name = "NULL"; return; } lock->name = name; 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); 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; 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"); dump_stack(); return 0; } if (lock->key == &__lockdep_no_validate__) check = 1; 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; } 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; 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; 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; 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"); 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=====================================\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 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; if (!class) class = look_up_lock_class(lock, 0); if (DEBUG_LOCKS_WARN_ON(!class)) return 0; 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; 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->nest_lock, hlock->acquire_ip, hlock->references)) 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 (match_held_lock(hlock, lock)) goto found_it; prev_hlock = hlock; } return print_unlock_inbalance_bug(curr, lock, ip); found_it: if (hlock->instance == lock) lock_release_holdtime(hlock); if (hlock->references) { hlock->references--; if (hlock->references) { /* * We had, and after removing one, still have * references, the current lock stack is still * valid. We're done! */ return 1; } } /* * 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, hlock->references)) 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 || hlock->references) 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); } static int __lock_is_held(struct lockdep_map *lock) { struct task_struct *curr = current; int i; for (i = 0; i < curr->lockdep_depth; i++) { struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) return 1; } return 0; } /* * 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_class(struct lockdep_map *lock, const char *name, struct lock_class_key *key, 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_class(lock, name, key, subclass, ip)) check_chain_key(current); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_set_class); /* * 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; trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); __lock_acquire(lock, subclass, trylock, read, check, irqs_disabled_flags(flags), nest_lock, ip, 0); 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; trace_lock_release(lock, ip); __lock_release(lock, nested, ip); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_release); int lock_is_held(struct lockdep_map *lock) { unsigned long flags; int ret = 0; if (unlikely(current->lockdep_recursion)) return ret; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; ret = __lock_is_held(lock); current->lockdep_recursion = 0; raw_local_irq_restore(flags); return ret; } EXPORT_SYMBOL_GPL(lock_is_held); void lockdep_set_current_reclaim_state(gfp_t gfp_mask) { current->lockdep_reclaim_gfp = gfp_mask; } void lockdep_clear_current_reclaim_state(void) { current->lockdep_reclaim_gfp = 0; } #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, contention_point, contending_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 (match_held_lock(hlock, lock)) goto found_it; prev_hlock = hlock; } print_lock_contention_bug(curr, lock, ip); return; found_it: if (hlock->instance != lock) return; hlock->waittime_stamp = lockstat_clock(); contention_point = lock_point(hlock_class(hlock)->contention_point, ip); contending_point = lock_point(hlock_class(hlock)->contending_point, lock->ip); stats = get_lock_stats(hlock_class(hlock)); if (contention_point < LOCKSTAT_POINTS) stats->contention_point[contention_point]++; if (contending_point < LOCKSTAT_POINTS) stats->contending_point[contending_point]++; if (lock->cpu != smp_processor_id()) stats->bounces[bounce_contended + !!hlock->read]++; put_lock_stats(stats); } static void __lock_acquired(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; u64 now, 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 (match_held_lock(hlock, lock)) goto found_it; prev_hlock = hlock; } print_lock_contention_bug(curr, lock, _RET_IP_); return; found_it: if (hlock->instance != lock) return; cpu = smp_processor_id(); if (hlock->waittime_stamp) { now = lockstat_clock(); waittime = now - hlock->waittime_stamp; hlock->holdtime_stamp = now; } trace_lock_acquired(lock, ip); 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; lock->ip = ip; } 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; trace_lock_contended(lock, ip); __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 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_acquired(lock, ip); 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 #ifdef CONFIG_PROVE_LOCKING + sizeof(struct circular_queue) #endif ) / 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; } else { if (count != 10) printk(KERN_CONT " 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); } } void lockdep_rcu_dereference(const char *file, const int line) { struct task_struct *curr = current; #ifndef CONFIG_PROVE_RCU_REPEATEDLY if (!debug_locks_off()) return; #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ /* Note: the following can be executed concurrently, so be careful. */ printk("\n===================================================\n"); printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n"); printk( "---------------------------------------------------\n"); printk("%s:%d invoked rcu_dereference_check() without protection!\n", file, line); printk("\nother info that might help us debug this:\n\n"); printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks); lockdep_print_held_locks(curr); printk("\nstack backtrace:\n"); dump_stack(); } EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);