diff options
| -rw-r--r-- | include/linux/lockdep.h | 53 | ||||
| -rw-r--r-- | kernel/lockdep.c | 247 | ||||
| -rw-r--r-- | kernel/sysctl.c | 22 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 11 |
4 files changed, 333 insertions, 0 deletions
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 14c937d345c..8f946f614f8 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -9,6 +9,7 @@ #define __LINUX_LOCKDEP_H struct task_struct; +struct lockdep_map; #ifdef CONFIG_LOCKDEP @@ -114,8 +115,32 @@ struct lock_class { const char *name; int name_version; + +#ifdef CONFIG_LOCK_STAT + unsigned long contention_point[4]; +#endif +}; + +#ifdef CONFIG_LOCK_STAT +struct lock_time { + s64 min; + s64 max; + s64 total; + unsigned long nr; }; +struct lock_class_stats { + unsigned long contention_point[4]; + struct lock_time read_waittime; + struct lock_time write_waittime; + struct lock_time read_holdtime; + struct lock_time write_holdtime; +}; + +struct lock_class_stats lock_stats(struct lock_class *class); +void clear_lock_stats(struct lock_class *class); +#endif + /* * Map the lock object (the lock instance) to the lock-class object. * This is embedded into specific lock instances: @@ -165,6 +190,10 @@ struct held_lock { unsigned long acquire_ip; struct lockdep_map *instance; +#ifdef CONFIG_LOCK_STAT + u64 waittime_stamp; + u64 holdtime_stamp; +#endif /* * The lock-stack is unified in that the lock chains of interrupt * contexts nest ontop of process context chains, but we 'separate' @@ -281,6 +310,30 @@ struct lock_class_key { }; #endif /* !LOCKDEP */ +#ifdef CONFIG_LOCK_STAT + +extern void lock_contended(struct lockdep_map *lock, unsigned long ip); +extern void lock_acquired(struct lockdep_map *lock); + +#define LOCK_CONTENDED(_lock, try, lock) \ +do { \ + if (!try(_lock)) { \ + lock_contended(&(_lock)->dep_map, _RET_IP_); \ + lock(_lock); \ + lock_acquired(&(_lock)->dep_map); \ + } \ +} while (0) + +#else /* CONFIG_LOCK_STAT */ + +#define lock_contended(lockdep_map, ip) do {} while (0) +#define lock_acquired(lockdep_map) do {} while (0) + +#define LOCK_CONTENDED(_lock, try, lock) \ + lock(_lock) + +#endif /* CONFIG_LOCK_STAT */ + #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS) extern void early_init_irq_lock_class(void); #else diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 87ac3642507..70ca4db28af 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -42,6 +42,20 @@ #include "lockdep_internals.h" +#ifdef CONFIG_PROVE_LOCKING +int prove_locking = 1; +module_param(prove_locking, int, 0644); +#else +#define prove_locking 0 +#endif + +#ifdef CONFIG_LOCK_STAT +int lock_stat = 1; +module_param(lock_stat, int, 0644); +#else +#define lock_stat 0 +#endif + /* * lockdep_lock: protects the lockdep graph, the hashes and the * class/list/hash allocators. @@ -104,6 +118,70 @@ static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; unsigned long nr_lock_classes; static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; +#ifdef CONFIG_LOCK_STAT +static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats); + +static int lock_contention_point(struct lock_class *class, unsigned long ip) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) { + if (class->contention_point[i] == 0) { + class->contention_point[i] = ip; + break; + } + if (class->contention_point[i] == ip) + break; + } + + return i; +} + +static void lock_time_inc(struct lock_time *lt, s64 time) +{ + if (time > lt->max) + lt->max = time; + + if (time < lt->min || !lt->min) + lt->min = time; + + lt->total += time; + lt->nr++; +} + +static struct lock_class_stats *get_lock_stats(struct lock_class *class) +{ + return &get_cpu_var(lock_stats)[class - lock_classes]; +} + +static void put_lock_stats(struct lock_class_stats *stats) +{ + put_cpu_var(lock_stats); +} + +static void lock_release_holdtime(struct held_lock *hlock) +{ + struct lock_class_stats *stats; + s64 holdtime; + + if (!lock_stat) + return; + + holdtime = sched_clock() - hlock->holdtime_stamp; + + stats = get_lock_stats(hlock->class); + if (hlock->read) + lock_time_inc(&stats->read_holdtime, holdtime); + else + lock_time_inc(&stats->write_holdtime, holdtime); + put_lock_stats(stats); +} +#else +static inline void lock_release_holdtime(struct held_lock *hlock) +{ +} +#endif + /* * We keep a global list of all lock classes. The list only grows, * never shrinks. The list is only accessed with the lockdep @@ -2221,6 +2299,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, int chain_head = 0; u64 chain_key; + if (!prove_locking) + check = 1; + if (unlikely(!debug_locks)) return 0; @@ -2271,6 +2352,10 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, hlock->read = read; hlock->check = check; hlock->hardirqs_off = hardirqs_off; +#ifdef CONFIG_LOCK_STAT + hlock->waittime_stamp = 0; + hlock->holdtime_stamp = sched_clock(); +#endif if (check == 2 && !mark_irqflags(curr, hlock)) return 0; @@ -2411,6 +2496,8 @@ lock_release_non_nested(struct task_struct *curr, return print_unlock_inbalance_bug(curr, lock, ip); found_it: + lock_release_holdtime(hlock); + /* * We have the right lock to unlock, 'hlock' points to it. * Now we remove it from the stack, and add back the other @@ -2463,6 +2550,8 @@ static int lock_release_nested(struct task_struct *curr, curr->curr_chain_key = hlock->prev_chain_key; + lock_release_holdtime(hlock); + #ifdef CONFIG_DEBUG_LOCKDEP hlock->prev_chain_key = 0; hlock->class = NULL; @@ -2537,6 +2626,9 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass, { unsigned long flags; + if (unlikely(!lock_stat && !prove_locking)) + return; + if (unlikely(current->lockdep_recursion)) return; @@ -2556,6 +2648,9 @@ void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) { unsigned long flags; + if (unlikely(!lock_stat && !prove_locking)) + return; + if (unlikely(current->lockdep_recursion)) return; @@ -2569,6 +2664,158 @@ void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) EXPORT_SYMBOL_GPL(lock_release); +#ifdef CONFIG_LOCK_STAT +static int +print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, + unsigned long ip) +{ + if (!debug_locks_off()) + return 0; + if (debug_locks_silent) + return 0; + + printk("\n=================================\n"); + printk( "[ BUG: bad contention detected! ]\n"); + printk( "---------------------------------\n"); + printk("%s/%d is trying to contend lock (", + curr->comm, curr->pid); + print_lockdep_cache(lock); + printk(") at:\n"); + print_ip_sym(ip); + printk("but there are no locks held!\n"); + printk("\nother info that might help us debug this:\n"); + lockdep_print_held_locks(curr); + + printk("\nstack backtrace:\n"); + dump_stack(); + + return 0; +} + +static void +__lock_contended(struct lockdep_map *lock, unsigned long ip) +{ + struct task_struct *curr = current; + struct held_lock *hlock, *prev_hlock; + struct lock_class_stats *stats; + unsigned int depth; + int i, point; + + depth = curr->lockdep_depth; + if (DEBUG_LOCKS_WARN_ON(!depth)) + return; + + prev_hlock = NULL; + for (i = depth-1; i >= 0; i--) { + hlock = curr->held_locks + i; + /* + * We must not cross into another context: + */ + if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) + break; + if (hlock->instance == lock) + goto found_it; + prev_hlock = hlock; + } + print_lock_contention_bug(curr, lock, ip); + return; + +found_it: + hlock->waittime_stamp = sched_clock(); + + point = lock_contention_point(hlock->class, ip); + + stats = get_lock_stats(hlock->class); + if (point < ARRAY_SIZE(stats->contention_point)) + stats->contention_point[i]++; + put_lock_stats(stats); +} + +static void +__lock_acquired(struct lockdep_map *lock) +{ + struct task_struct *curr = current; + struct held_lock *hlock, *prev_hlock; + struct lock_class_stats *stats; + unsigned int depth; + u64 now; + s64 waittime; + int i; + + depth = curr->lockdep_depth; + if (DEBUG_LOCKS_WARN_ON(!depth)) + return; + + prev_hlock = NULL; + for (i = depth-1; i >= 0; i--) { + hlock = curr->held_locks + i; + /* + * We must not cross into another context: + */ + if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) + break; + if (hlock->instance == lock) + goto found_it; + prev_hlock = hlock; + } + print_lock_contention_bug(curr, lock, _RET_IP_); + return; + +found_it: + if (!hlock->waittime_stamp) + return; + + now = sched_clock(); + waittime = now - hlock->waittime_stamp; + hlock->holdtime_stamp = now; + + stats = get_lock_stats(hlock->class); + if (hlock->read) + lock_time_inc(&stats->read_waittime, waittime); + else + lock_time_inc(&stats->write_waittime, waittime); + put_lock_stats(stats); +} + +void lock_contended(struct lockdep_map *lock, unsigned long ip) +{ + unsigned long flags; + + if (unlikely(!lock_stat)) + return; + + if (unlikely(current->lockdep_recursion)) + return; + + raw_local_irq_save(flags); + check_flags(flags); + current->lockdep_recursion = 1; + __lock_contended(lock, ip); + current->lockdep_recursion = 0; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(lock_contended); + +void lock_acquired(struct lockdep_map *lock) +{ + unsigned long flags; + + if (unlikely(!lock_stat)) + return; + + if (unlikely(current->lockdep_recursion)) + return; + + raw_local_irq_save(flags); + check_flags(flags); + current->lockdep_recursion = 1; + __lock_acquired(lock); + current->lockdep_recursion = 0; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(lock_acquired); +#endif + /* * Used by the testsuite, sanitize the validator state * after a simulated failure: diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 2aaa3f98185..e69179b1809 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -161,6 +161,8 @@ extern ctl_table inotify_table[]; int sysctl_legacy_va_layout; #endif +extern int prove_locking; +extern int lock_stat; /* The default sysctl tables: */ @@ -282,6 +284,26 @@ static ctl_table kern_table[] = { .mode = 0644, .proc_handler = &proc_dointvec, }, +#ifdef CONFIG_PROVE_LOCKING + { + .ctl_name = CTL_UNNUMBERED, + .procname = "prove_locking", + .data = &prove_locking, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, +#endif +#ifdef CONFIG_LOCK_STAT + { + .ctl_name = CTL_UNNUMBERED, + .procname = "lock_stat", + .data = &lock_stat, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, +#endif { .ctl_name = CTL_UNNUMBERED, .procname = "sched_features", diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 640844024ff..f3e0c2abcbd 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -283,6 +283,17 @@ config LOCKDEP select KALLSYMS select KALLSYMS_ALL +config LOCK_STAT + bool "Lock usage statisitics" + depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT + select LOCKDEP + select DEBUG_SPINLOCK + select DEBUG_MUTEXES + select DEBUG_LOCK_ALLOC + default n + help + This feature enables tracking lock contention points + config DEBUG_LOCKDEP bool "Lock dependency engine debugging" depends on DEBUG_KERNEL && LOCKDEP |