diff options
| -rw-r--r-- | include/linux/hardirq.h | 5 | ||||
| -rw-r--r-- | include/linux/init_task.h | 2 | ||||
| -rw-r--r-- | include/linux/lockdep.h | 347 | ||||
| -rw-r--r-- | include/linux/sched.h | 7 | ||||
| -rw-r--r-- | init/main.c | 14 | ||||
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/fork.c | 5 | ||||
| -rw-r--r-- | kernel/irq/manage.c | 6 | ||||
| -rw-r--r-- | kernel/lockdep.c | 2703 | ||||
| -rw-r--r-- | kernel/lockdep_internals.h | 78 | ||||
| -rw-r--r-- | kernel/module.c | 3 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 2 | ||||
| -rw-r--r-- | lib/locking-selftest.c | 4 |
13 files changed, 3171 insertions, 6 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index b1d4332b5cf..50d8b5744cf 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -3,6 +3,7 @@ #include <linux/preempt.h> #include <linux/smp_lock.h> +#include <linux/lockdep.h> #include <asm/hardirq.h> #include <asm/system.h> @@ -122,7 +123,7 @@ static inline void account_system_vtime(struct task_struct *tsk) */ extern void irq_exit(void); -#define nmi_enter() irq_enter() -#define nmi_exit() __irq_exit() +#define nmi_enter() do { lockdep_off(); irq_enter(); } while (0) +#define nmi_exit() do { __irq_exit(); lockdep_on(); } while (0) #endif /* LINUX_HARDIRQ_H */ diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 444a3ae0de2..60aac2cea0c 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -4,6 +4,7 @@ #include <linux/file.h> #include <linux/rcupdate.h> #include <linux/irqflags.h> +#include <linux/lockdep.h> #define INIT_FDTABLE \ { \ @@ -126,6 +127,7 @@ extern struct group_info init_groups; .fs_excl = ATOMIC_INIT(0), \ .pi_lock = SPIN_LOCK_UNLOCKED, \ INIT_TRACE_IRQFLAGS \ + INIT_LOCKDEP \ } diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h new file mode 100644 index 00000000000..80ec7a4dbc9 --- /dev/null +++ b/include/linux/lockdep.h @@ -0,0 +1,347 @@ +/* + * Runtime locking correctness validator + * + * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> + * + * see Documentation/lockdep-design.txt for more details. + */ +#ifndef __LINUX_LOCKDEP_H +#define __LINUX_LOCKDEP_H + +#include <linux/linkage.h> +#include <linux/list.h> +#include <linux/debug_locks.h> +#include <linux/stacktrace.h> + +#ifdef CONFIG_LOCKDEP + +/* + * Lock-class usage-state bits: + */ +enum lock_usage_bit +{ + LOCK_USED = 0, + LOCK_USED_IN_HARDIRQ, + LOCK_USED_IN_SOFTIRQ, + LOCK_ENABLED_SOFTIRQS, + LOCK_ENABLED_HARDIRQS, + LOCK_USED_IN_HARDIRQ_READ, + LOCK_USED_IN_SOFTIRQ_READ, + LOCK_ENABLED_SOFTIRQS_READ, + LOCK_ENABLED_HARDIRQS_READ, + LOCK_USAGE_STATES +}; + +/* + * Usage-state bitmasks: + */ +#define LOCKF_USED (1 << LOCK_USED) +#define LOCKF_USED_IN_HARDIRQ (1 << LOCK_USED_IN_HARDIRQ) +#define LOCKF_USED_IN_SOFTIRQ (1 << LOCK_USED_IN_SOFTIRQ) +#define LOCKF_ENABLED_HARDIRQS (1 << LOCK_ENABLED_HARDIRQS) +#define LOCKF_ENABLED_SOFTIRQS (1 << LOCK_ENABLED_SOFTIRQS) + +#define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS) +#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ) + +#define LOCKF_USED_IN_HARDIRQ_READ (1 << LOCK_USED_IN_HARDIRQ_READ) +#define LOCKF_USED_IN_SOFTIRQ_READ (1 << LOCK_USED_IN_SOFTIRQ_READ) +#define LOCKF_ENABLED_HARDIRQS_READ (1 << LOCK_ENABLED_HARDIRQS_READ) +#define LOCKF_ENABLED_SOFTIRQS_READ (1 << LOCK_ENABLED_SOFTIRQS_READ) + +#define LOCKF_ENABLED_IRQS_READ \ + (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ) +#define LOCKF_USED_IN_IRQ_READ \ + (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ) + +#define MAX_LOCKDEP_SUBCLASSES 8UL + +/* + * Lock-classes are keyed via unique addresses, by embedding the + * lockclass-key into the kernel (or module) .data section. (For + * static locks we use the lock address itself as the key.) + */ +struct lockdep_subclass_key { + char __one_byte; +} __attribute__ ((__packed__)); + +struct lock_class_key { + struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES]; +}; + +/* + * The lock-class itself: + */ +struct lock_class { + /* + * class-hash: + */ + struct list_head hash_entry; + + /* + * global list of all lock-classes: + */ + struct list_head lock_entry; + + struct lockdep_subclass_key *key; + unsigned int subclass; + + /* + * IRQ/softirq usage tracking bits: + */ + unsigned long usage_mask; + struct stack_trace usage_traces[LOCK_USAGE_STATES]; + + /* + * These fields represent a directed graph of lock dependencies, + * to every node we attach a list of "forward" and a list of + * "backward" graph nodes. + */ + struct list_head locks_after, locks_before; + + /* + * Generation counter, when doing certain classes of graph walking, + * to ensure that we check one node only once: + */ + unsigned int version; + + /* + * Statistics counter: + */ + unsigned long ops; + + const char *name; + int name_version; +}; + +/* + * Map the lock object (the lock instance) to the lock-class object. + * This is embedded into specific lock instances: + */ +struct lockdep_map { + struct lock_class_key *key; + struct lock_class *class[MAX_LOCKDEP_SUBCLASSES]; + const char *name; +}; + +/* + * Every lock has a list of other locks that were taken after it. + * We only grow the list, never remove from it: + */ +struct lock_list { + struct list_head entry; + struct lock_class *class; + struct stack_trace trace; +}; + +/* + * We record lock dependency chains, so that we can cache them: + */ +struct lock_chain { + struct list_head entry; + u64 chain_key; +}; + +struct held_lock { + /* + * One-way hash of the dependency chain up to this point. We + * hash the hashes step by step as the dependency chain grows. + * + * We use it for dependency-caching and we skip detection + * passes and dependency-updates if there is a cache-hit, so + * it is absolutely critical for 100% coverage of the validator + * to have a unique key value for every unique dependency path + * that can occur in the system, to make a unique hash value + * as likely as possible - hence the 64-bit width. + * + * The task struct holds the current hash value (initialized + * with zero), here we store the previous hash value: + */ + u64 prev_chain_key; + struct lock_class *class; + unsigned long acquire_ip; + struct lockdep_map *instance; + + /* + * The lock-stack is unified in that the lock chains of interrupt + * contexts nest ontop of process context chains, but we 'separate' + * the hashes by starting with 0 if we cross into an interrupt + * context, and we also keep do not add cross-context lock + * dependencies - the lock usage graph walking covers that area + * anyway, and we'd just unnecessarily increase the number of + * dependencies otherwise. [Note: hardirq and softirq contexts + * are separated from each other too.] + * + * The following field is used to detect when we cross into an + * interrupt context: + */ + int irq_context; + int trylock; + int read; + int check; + int hardirqs_off; +}; + +/* + * Initialization, self-test and debugging-output methods: + */ +extern void lockdep_init(void); +extern void lockdep_info(void); +extern void lockdep_reset(void); +extern void lockdep_reset_lock(struct lockdep_map *lock); +extern void lockdep_free_key_range(void *start, unsigned long size); + +extern void lockdep_off(void); +extern void lockdep_on(void); +extern int lockdep_internal(void); + +/* + * These methods are used by specific locking variants (spinlocks, + * rwlocks, mutexes and rwsems) to pass init/acquire/release events + * to lockdep: + */ + +extern void lockdep_init_map(struct lockdep_map *lock, const char *name, + struct lock_class_key *key); + +/* + * Reinitialize a lock key - for cases where there is special locking or + * special initialization of locks so that the validator gets the scope + * of dependencies wrong: they are either too broad (they need a class-split) + * or they are too narrow (they suffer from a false class-split): + */ +#define lockdep_set_class(lock, key) \ + lockdep_init_map(&(lock)->dep_map, #key, key) +#define lockdep_set_class_and_name(lock, key, name) \ + lockdep_init_map(&(lock)->dep_map, name, key) + +/* + * Acquire a lock. + * + * Values for "read": + * + * 0: exclusive (write) acquire + * 1: read-acquire (no recursion allowed) + * 2: read-acquire with same-instance recursion allowed + * + * Values for check: + * + * 0: disabled + * 1: simple checks (freeing, held-at-exit-time, etc.) + * 2: full validation + */ +extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass, + int trylock, int read, int check, unsigned long ip); + +extern void lock_release(struct lockdep_map *lock, int nested, + unsigned long ip); + +# define INIT_LOCKDEP .lockdep_recursion = 0, + +#else /* !LOCKDEP */ + +static inline void lockdep_off(void) +{ +} + +static inline void lockdep_on(void) +{ +} + +static inline int lockdep_internal(void) +{ + return 0; +} + +# define lock_acquire(l, s, t, r, c, i) do { } while (0) +# define lock_release(l, n, i) do { } while (0) +# define lockdep_init() do { } while (0) +# define lockdep_info() do { } while (0) +# define lockdep_init_map(lock, name, key) do { (void)(key); } while (0) +# define lockdep_set_class(lock, key) do { (void)(key); } while (0) +# define lockdep_set_class_and_name(lock, key, name) \ + do { (void)(key); } while (0) +# define INIT_LOCKDEP +# define lockdep_reset() do { debug_locks = 1; } while (0) +# define lockdep_free_key_range(start, size) do { } while (0) +/* + * The class key takes no space if lockdep is disabled: + */ +struct lock_class_key { }; +#endif /* !LOCKDEP */ + +#ifdef CONFIG_TRACE_IRQFLAGS +extern void early_boot_irqs_off(void); +extern void early_boot_irqs_on(void); +#else +# define early_boot_irqs_off() do { } while (0) +# define early_boot_irqs_on() do { } while (0) +#endif + +/* + * For trivial one-depth nesting of a lock-class, the following + * global define can be used. (Subsystems with multiple levels + * of nesting should define their own lock-nesting subclasses.) + */ +#define SINGLE_DEPTH_NESTING 1 + +/* + * Map the dependency ops to NOP or to real lockdep ops, depending + * on the per lock-class debug mode: + */ + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# ifdef CONFIG_PROVE_LOCKING +# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i) +# else +# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i) +# endif +# define spin_release(l, n, i) lock_release(l, n, i) +#else +# define spin_acquire(l, s, t, i) do { } while (0) +# define spin_release(l, n, i) do { } while (0) +#endif + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# ifdef CONFIG_PROVE_LOCKING +# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i) +# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, i) +# else +# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i) +# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 1, i) +# endif +# define rwlock_release(l, n, i) lock_release(l, n, i) +#else +# define rwlock_acquire(l, s, t, i) do { } while (0) +# define rwlock_acquire_read(l, s, t, i) do { } while (0) +# define rwlock_release(l, n, i) do { } while (0) +#endif + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# ifdef CONFIG_PROVE_LOCKING +# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i) +# else +# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i) +# endif +# define mutex_release(l, n, i) lock_release(l, n, i) +#else +# define mutex_acquire(l, s, t, i) do { } while (0) +# define mutex_release(l, n, i) do { } while (0) +#endif + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# ifdef CONFIG_PROVE_LOCKING +# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i) +# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, i) +# else +# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i) +# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, i) +# endif +# define rwsem_release(l, n, i) lock_release(l, n, i) +#else +# define rwsem_acquire(l, s, t, i) do { } while (0) +# define rwsem_acquire_read(l, s, t, i) do { } while (0) +# define rwsem_release(l, n, i) do { } while (0) +#endif + +#endif /* __LINUX_LOCKDEP_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index ad7a89014d2..8ebddba4448 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -886,6 +886,13 @@ struct task_struct { int hardirq_context; int softirq_context; #endif +#ifdef CONFIG_LOCKDEP +# define MAX_LOCK_DEPTH 30UL + u64 curr_chain_key; + int lockdep_depth; + struct held_lock held_locks[MAX_LOCK_DEPTH]; + unsigned int lockdep_recursion; +#endif /* journalling filesystem info */ void *journal_info; diff --git a/init/main.c b/init/main.c index fc73e1cd861..fc473d4b56f 100644 --- a/init/main.c +++ b/init/main.c @@ -48,6 +48,7 @@ #include <linux/unwind.h> #include <linux/buffer_head.h> #include <linux/debug_locks.h> +#include <linux/lockdep.h> #include <asm/io.h> #include <asm/bugs.h> @@ -457,6 +458,15 @@ asmlinkage void __init start_kernel(void) smp_setup_processor_id(); + /* + * Need to run as early as possible, to initialize the + * lockdep hash: + */ + lockdep_init(); + + local_irq_disable(); + early_boot_irqs_off(); + /* * Interrupts are still disabled. Do necessary setups, then * enable them @@ -502,6 +512,7 @@ asmlinkage void __init start_kernel(void) profile_init(); if (!irqs_disabled()) printk("start_kernel(): bug: interrupts were enabled early\n"); + early_boot_irqs_on(); local_irq_enable(); /* @@ -512,6 +523,9 @@ asmlinkage void __init start_kernel(void) console_init(); if (panic_later) panic(panic_later, panic_param); + + lockdep_info(); + /* * Need to run this when irqs are enabled, because it wants * to self-test [hard/soft]-irqs on/off lock inversion bugs diff --git a/kernel/Makefile b/kernel/Makefile index e7fd20e70f1..049aa79e5c1 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -13,6 +13,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \ obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-y += time/ obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o +obj-$(CONFIG_LOCKDEP) += lockdep.o obj-$(CONFIG_FUTEX) += futex.o ifeq ($(CONFIG_COMPAT),y) obj-$(CONFIG_FUTEX) += futex_compat.o diff --git a/kernel/fork.c b/kernel/fork.c index b7db7fb74f5..7f48abdd7bb 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1061,6 +1061,11 @@ static task_t *copy_process(unsigned long clone_flags, p->hardirq_context = 0; p->softirq_context = 0; #endif +#ifdef CONFIG_LOCKDEP + p->lockdep_depth = 0; /* no locks held yet */ + p->curr_chain_key = 0; + p->lockdep_recursion = 0; +#endif rt_mutex_init_task(p); diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index c911c6ec4dd..4e461438e48 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -410,6 +410,12 @@ int request_irq(unsigned int irq, struct irqaction *action; int retval; +#ifdef CONFIG_LOCKDEP + /* + * Lockdep wants atomic interrupt handlers: + */ + irqflags |= SA_INTERRUPT; +#endif /* * Sanity-check: shared interrupts must pass in a real dev-ID, * otherwise we'll have trouble later trying to figure out diff --git a/kernel/lockdep.c b/kernel/lockdep.c new file mode 100644 index 00000000000..dd0580910a9 --- /dev/null +++ b/kernel/lockdep.c @@ -0,0 +1,2703 @@ +/* + * kernel/lockdep.c + * + * Runtime locking correctness validator + * + * Started by Ingo Molnar: + * + * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> + * + * this code maps all the lock dependencies as they occur in a live kernel + * and will warn about the following classes of locking bugs: + * + * - lock inversion scenarios + * - circular lock dependencies + * - hardirq/softirq safe/unsafe locking bugs + * + * Bugs are reported even if the current locking scenario does not cause + * any deadlock at this point. + * + * I.e. if anytime in the past two locks were taken in a different order, + * even if it happened for another task, even if those were different + * locks (but of the same class as this lock), this code will detect it. + * + * Thanks to Arjan van de Ven for coming up with the initial idea of + * mapping lock dependencies runtime. + */ +#include <linux/mutex.h> +#include <linux/sched.h> +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/spinlock.h> +#include <linux/kallsyms.h> +#include <linux/interrupt.h> +#include <linux/stacktrace.h> +#include <linux/debug_locks.h> +#include <linux/irqflags.h> + +#include <asm/sections.h> + +#include "lockdep_internals.h" + +/* + * hash_lock: protects the lockdep hashes and class/list/hash allocators. + * + * This is one of the rare exceptions where it's justified + * to use a raw spinlock - we really dont want the spinlock + * code to recurse back into the lockdep code. + */ +static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; + +static int lockdep_initialized; + +unsigned long nr_list_entries; +static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; + +/* + * Allocate a lockdep entry. (assumes hash_lock held, returns + * with NULL on failure) + */ +static struct lock_list *alloc_list_entry(void) +{ + if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { + __raw_spin_unlock(&hash_lock); + debug_locks_off(); + printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); + printk("turning off the locking correctness validator.\n"); + return NULL; + } + return list_entries + nr_list_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]; + +/* + * 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 CLASSHASH_MASK (CLASSHASH_SIZE - 1) +#define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK) +#define classhashentry(key) (classhash_table + __classhashfn((key))) + +static struct list_head classhash_table[CLASSHASH_SIZE]; + +unsigned long nr_lock_chains; +static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; + +/* + * 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 CHAINHASH_MASK (CHAINHASH_SIZE - 1) +#define __chainhashfn(chain) \ + (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK) +#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/2) ^ \ + ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS/2)) ^ \ + (key2)) + +void lockdep_off(void) +{ + current->lockdep_recursion++; +} + +EXPORT_SYMBOL(lockdep_off); + +void lockdep_on(void) +{ + current->lockdep_recursion--; +} + +EXPORT_SYMBOL(lockdep_on); + +int lockdep_internal(void) +{ + return current->lockdep_recursion != 0; +} + +EXPORT_SYMBOL(lockdep_internal); + +/* + * Debugging switches: + */ + +#define VERBOSE 0 +#ifdef VERBOSE +# define VERY_VERBOSE 0 +#endif + +#if VERBOSE +# define HARDIRQ_VERBOSE 1 +# define SOFTIRQ_VERBOSE 1 +#else +# define HARDIRQ_VERBOSE 0 +# define SOFTIRQ_VERBOSE 0 +#endif + +#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE +/* + * Quick filtering for interesting events: + */ +static int class_filter(struct lock_class *class) +{ + if (class->name_version == 1 && + !strcmp(class->name, "&rl->lock")) + return 1; + if (class->name_version == 1 && + !strcmp(class->name, "&ni->mrec_lock")) + return 1; + if (class->name_version == 1 && + !strcmp(class->name, "mft_ni_runlist_lock")) + return 1; + if (class->name_version == 1 && + !strcmp(class->name, "mft_ni_mrec_lock")) + return 1; + if (class->name_version == 1 && + !strcmp(class->name, "&vol->lcnbmp_lock")) + return 1; + return 0; +} +#endif + +static int verbose(struct lock_class *class) +{ +#if VERBOSE + return class_filter(class); +#endif + return 0; +} + +#ifdef CONFIG_TRACE_IRQFLAGS + +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; +} + +#endif + +/* + * Stack-trace: tightly packed array of stack backtrace + * addresses. Protected by the hash_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; + + save_stack_trace(trace, NULL, 0, 3); + + trace->max_entries = trace->nr_entries; + + nr_stack_trace_entries += trace->nr_entries; + if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) + return 0; + + if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) { + __raw_spin_unlock(&hash_lock); + if (debug_locks_off()) { + printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); + printk("turning off the locking correctness validator.\n"); + dump_stack(); + } + return 0; + } + + return 1; +} + +unsigned int nr_hardirq_chains; +unsigned int nr_softirq_chains; +unsigned int nr_process_chains; +unsigned int max_lockdep_depth; +unsigned int max_recursion_depth; + +#ifdef CONFIG_DEBUG_LOCKDEP +/* + * We cannot printk in early bootup code. Not even early_printk() + * might work. So we mark any initialization errors and printk + * about it later on, in lockdep_info(). + */ +static int lockdep_init_error; + +/* + * Various lockdep statistics: + */ +atomic_t chain_lookup_hits; +atomic_t chain_lookup_misses; +atomic_t hardirqs_on_events; +atomic_t hardirqs_off_events; +atomic_t redundant_hardirqs_on; +atomic_t redundant_hardirqs_off; +atomic_t softirqs_on_events; +atomic_t softirqs_off_events; +atomic_t redundant_softirqs_on; +atomic_t redundant_softirqs_off; +atomic_t nr_unused_locks; +atomic_t nr_cyclic_checks; +atomic_t nr_cyclic_check_recursions; +atomic_t nr_find_usage_forwards_checks; +atomic_t nr_find_usage_forwards_recursions; +atomic_t nr_find_usage_backwards_checks; +atomic_t nr_find_usage_backwards_recursions; +# define debug_atomic_inc(ptr) atomic_inc(ptr) +# define debug_atomic_dec(ptr) atomic_dec(ptr) +# define debug_atomic_read(ptr) atomic_read(ptr) +#else +# define debug_atomic_inc(ptr) do { } while (0) +# define debug_atomic_dec(ptr) do { } while (0) +# define debug_atomic_read(ptr) 0 +#endif + +/* + * Locking printouts: + */ + +static const char *usage_str[] = +{ + [LOCK_USED] = "initial-use ", + [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W", + [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W", + [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W", + [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W", + [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R", + [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R", + [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R", + [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R", +}; + +const char * __get_key_name(struct lockdep_subclass_key *key, char *str) +{ + unsigned long offs, size; + char *modname; + + return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str); +} + +void +get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4) +{ + *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.'; + + if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) + *c1 = '+'; + else + if (class->usage_mask & LOCKF_ENABLED_HARDIRQS) + *c1 = '-'; + + if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) + *c2 = '+'; + else + if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS) + *c2 = '-'; + + if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) + *c3 = '-'; + if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) { + *c3 = '+'; + if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) + *c3 = '?'; + } + + if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) + *c4 = '-'; + if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) { + *c4 = '+'; + if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) + *c4 = '?'; + } +} + +static void print_lock_name(struct lock_class *class) +{ + char str[128], c1, c2, c3, c4; + const char *name; + + get_usage_chars(class, &c1, &c2, &c3, &c4); + + name = class->name; + if (!name) { + name = __get_key_name(class->key, str); + printk(" (%s", name); + } else { + printk(" (%s", name); + if (class->name_version > 1) + printk("#%d", class->name_version); + if (class->subclass) + printk("/%d", class->subclass); + } + printk("){%c%c%c%c}", c1, c2, c3, c4); +} + +static void print_lockdep_cache(struct lockdep_map *lock) +{ + const char *name; + char str[128]; + + name = lock->name; + if (!name) + name = __get_key_name(lock->key->subkeys, str); + + printk("%s", name); +} + +static void print_lock(struct held_lock *hlock) +{ + print_lock_name(hlock->class); + printk(", at: "); + print_ip_sym(hlock->acquire_ip); +} + +static void lockdep_print_held_locks(struct task_struct *curr) +{ + int i, depth = curr->lockdep_depth; + + if (!depth) { + printk("no locks held by %s/%d.\n", curr->comm, curr->pid); + return; + } + printk("%d lock%s held by %s/%d:\n", + depth, depth > 1 ? "s" : "", curr->comm, curr->pid); + + for (i = 0; i < depth; i++) { + printk(" #%d: ", i); + print_lock(curr->held_locks + i); + } +} +/* + * Helper to print a nice hierarchy of lock dependencies: + */ +static void print_spaces(int nr) +{ + int i; + + for (i = 0; i < nr; i++) + printk(" "); +} + +static void print_lock_class_header(struct lock_class *class, int depth) +{ + int bit; + + print_spaces(depth); + printk("->"); + 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; + + print_spaces(depth); + len += printk(" %s", usage_str[bit]); + len += printk(" at:\n"); + print_stack_trace(class->usage_traces + bit, len); + } + } + print_spaces(depth); + printk(" }\n"); + + print_spaces(depth); + printk(" ... key at: "); + print_ip_sym((unsigned long)class->key); +} + +/* + * printk all lock dependencies starting at <entry>: + */ +static void print_lock_dependencies(struct lock_class *class, int depth) +{ + struct lock_list *entry; + + if (DEBUG_LOCKS_WARN_ON(depth >= 20)) + return; + + print_lock_class_header(class, depth); + + list_for_each_entry(entry, &class->locks_after, entry) { + DEBUG_LOCKS_WARN_ON(!entry->class); + print_lock_dependencies(entry->class, depth + 1); + + print_spaces(depth); + printk(" ... acquired at:\n"); + print_stack_trace(&entry->trace, 2); + printk("\n"); + } +} + +/* + * 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) +{ + 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; + save_trace(&entry->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; +} + +/* + * Recursive, forwards-direction lock-dependency checking, used for + * both noncyclic checking and for hardirq-unsafe/softirq-unsafe + * checking. + * + * (to keep the stackframe of the recursive functions small we + * use these global variables, and we also mark various helper + * functions as noinline.) + */ +static struct held_lock *check_source, *check_target; + +/* + * Print a dependency chain entry (this is only done when a deadlock + * has been detected): + */ +static noinline int +print_circular_bug_entry(struct lock_list *target, unsigned int depth) +{ + if (debug_locks_silent) + return 0; + printk("\n-> #%u", depth); + print_lock_name(target->class); + printk(":\n"); + print_stack_trace(&target->trace, 6); + + return 0; +} + +/* + * When a circular dependency is detected, print the + * header first: + */ +static noinline int +print_circular_bug_header(struct lock_list *entry, unsigned int depth) +{ + struct task_struct *curr = current; + + __raw_spin_unlock(&hash_lock); + debug_locks_off(); + if (debug_locks_silent) + return 0; + + printk("\n=======================================================\n"); + printk( "[ INFO: possible circular locking dependency detected ]\n"); + printk( "-------------------------------------------------------\n"); + printk("%s/%d is trying to acquire lock:\n", + curr->comm, curr->pid); + print_lock(check_source); + printk("\nbut task is already holding lock:\n"); + print_lock(check_target); + printk("\nwhich lock already depends on the new lock.\n\n"); + printk("\nthe existing dependency chain (in reverse order) is:\n"); + + print_circular_bug_entry(entry, depth); + + return 0; +} + +static noinline int print_circular_bug_tail(void) +{ + struct task_struct *curr = current; + struct lock_list this; + + if (debug_locks_silent) + return 0; + + this.class = check_source->class; + save_trace(&this.trace); + print_circular_bug_entry(&this, 0); + + printk("\nother info that might help us debug this:\n\n"); + lockdep_print_held_locks(curr); + + printk("\nstack backtrace:\n"); + dump_stack(); + + return 0; +} + +static int noinline print_infinite_recursion_bug(void) +{ + __raw_spin_unlock(&hash_lock); + DEBUG_LOCKS_WARN_ON(1); + + return 0; +} |