linux/kernel/lockdep_proc.c
Frederic Weisbecker bd6d29c25b lockstat: Make lockstat counting per cpu
Locking statistics are implemented using global atomic
variables. This is usually fine unless some path write them very
often.

This is the case for the function and function graph tracers
that disable irqs for each entry saved (except if the function
tracer is in preempt disabled only mode).
And calls to local_irq_save/restore() increment
hardirqs_on_events and hardirqs_off_events stats (or similar
stats for redundant versions).

Incrementing these global vars for each function ends up in too
much cache bouncing if lockstats are enabled.

To solve this, implement the debug_atomic_*() operations using
per cpu vars.

 -v2: Use per_cpu() instead of get_cpu_var() to fetch the desired
      cpu vars on debug_atomic_read()

 -v3: Store the stats in a structure. No need for local_t as we
      are NMI/irq safe.

 -v4: Fix tons of build errors. I thought I had tested it but I
      probably forgot to select the relevant config.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1270505417-8144-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
2010-04-06 00:15:37 +02:00

692 lines
17 KiB
C

/*
* kernel/lockdep_proc.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>
*
* Code for /proc/lockdep and /proc/lockdep_stats:
*
*/
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
#include <linux/debug_locks.h>
#include <linux/vmalloc.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
#include <asm/div64.h>
#include "lockdep_internals.h"
static void *l_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &all_lock_classes, pos);
}
static void *l_start(struct seq_file *m, loff_t *pos)
{
return seq_list_start_head(&all_lock_classes, *pos);
}
static void l_stop(struct seq_file *m, void *v)
{
}
static void print_name(struct seq_file *m, struct lock_class *class)
{
char str[128];
const char *name = class->name;
if (!name) {
name = __get_key_name(class->key, str);
seq_printf(m, "%s", name);
} else{
seq_printf(m, "%s", name);
if (class->name_version > 1)
seq_printf(m, "#%d", class->name_version);
if (class->subclass)
seq_printf(m, "/%d", class->subclass);
}
}
static int l_show(struct seq_file *m, void *v)
{
struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
struct lock_list *entry;
char usage[LOCK_USAGE_CHARS];
if (v == &all_lock_classes) {
seq_printf(m, "all lock classes:\n");
return 0;
}
seq_printf(m, "%p", class->key);
#ifdef CONFIG_DEBUG_LOCKDEP
seq_printf(m, " OPS:%8ld", class->ops);
#endif
#ifdef CONFIG_PROVE_LOCKING
seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
#endif
get_usage_chars(class, usage);
seq_printf(m, " %s", usage);
seq_printf(m, ": ");
print_name(m, class);
seq_puts(m, "\n");
list_for_each_entry(entry, &class->locks_after, entry) {
if (entry->distance == 1) {
seq_printf(m, " -> [%p] ", entry->class->key);
print_name(m, entry->class);
seq_puts(m, "\n");
}
}
seq_puts(m, "\n");
return 0;
}
static const struct seq_operations lockdep_ops = {
.start = l_start,
.next = l_next,
.stop = l_stop,
.show = l_show,
};
static int lockdep_open(struct inode *inode, struct file *file)
{
return seq_open(file, &lockdep_ops);
}
static const struct file_operations proc_lockdep_operations = {
.open = lockdep_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
#ifdef CONFIG_PROVE_LOCKING
static void *lc_start(struct seq_file *m, loff_t *pos)
{
if (*pos == 0)
return SEQ_START_TOKEN;
if (*pos - 1 < nr_lock_chains)
return lock_chains + (*pos - 1);
return NULL;
}
static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return lc_start(m, pos);
}
static void lc_stop(struct seq_file *m, void *v)
{
}
static int lc_show(struct seq_file *m, void *v)
{
struct lock_chain *chain = v;
struct lock_class *class;
int i;
if (v == SEQ_START_TOKEN) {
seq_printf(m, "all lock chains:\n");
return 0;
}
seq_printf(m, "irq_context: %d\n", chain->irq_context);
for (i = 0; i < chain->depth; i++) {
class = lock_chain_get_class(chain, i);
if (!class->key)
continue;
seq_printf(m, "[%p] ", class->key);
print_name(m, class);
seq_puts(m, "\n");
}
seq_puts(m, "\n");
return 0;
}
static const struct seq_operations lockdep_chains_ops = {
.start = lc_start,
.next = lc_next,
.stop = lc_stop,
.show = lc_show,
};
static int lockdep_chains_open(struct inode *inode, struct file *file)
{
return seq_open(file, &lockdep_chains_ops);
}
static const struct file_operations proc_lockdep_chains_operations = {
.open = lockdep_chains_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
#endif /* CONFIG_PROVE_LOCKING */
static void lockdep_stats_debug_show(struct seq_file *m)
{
#ifdef CONFIG_DEBUG_LOCKDEP
unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
hi2 = debug_atomic_read(hardirqs_off_events),
hr1 = debug_atomic_read(redundant_hardirqs_on),
hr2 = debug_atomic_read(redundant_hardirqs_off),
si1 = debug_atomic_read(softirqs_on_events),
si2 = debug_atomic_read(softirqs_off_events),
sr1 = debug_atomic_read(redundant_softirqs_on),
sr2 = debug_atomic_read(redundant_softirqs_off);
seq_printf(m, " chain lookup misses: %11llu\n",
debug_atomic_read(chain_lookup_misses));
seq_printf(m, " chain lookup hits: %11llu\n",
debug_atomic_read(chain_lookup_hits));
seq_printf(m, " cyclic checks: %11llu\n",
debug_atomic_read(nr_cyclic_checks));
seq_printf(m, " find-mask forwards checks: %11llu\n",
debug_atomic_read(nr_find_usage_forwards_checks));
seq_printf(m, " find-mask backwards checks: %11llu\n",
debug_atomic_read(nr_find_usage_backwards_checks));
seq_printf(m, " hardirq on events: %11llu\n", hi1);
seq_printf(m, " hardirq off events: %11llu\n", hi2);
seq_printf(m, " redundant hardirq ons: %11llu\n", hr1);
seq_printf(m, " redundant hardirq offs: %11llu\n", hr2);
seq_printf(m, " softirq on events: %11llu\n", si1);
seq_printf(m, " softirq off events: %11llu\n", si2);
seq_printf(m, " redundant softirq ons: %11llu\n", sr1);
seq_printf(m, " redundant softirq offs: %11llu\n", sr2);
#endif
}
static int lockdep_stats_show(struct seq_file *m, void *v)
{
struct lock_class *class;
unsigned long nr_unused = 0, nr_uncategorized = 0,
nr_irq_safe = 0, nr_irq_unsafe = 0,
nr_softirq_safe = 0, nr_softirq_unsafe = 0,
nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
sum_forward_deps = 0, factor = 0;
list_for_each_entry(class, &all_lock_classes, lock_entry) {
if (class->usage_mask == 0)
nr_unused++;
if (class->usage_mask == LOCKF_USED)
nr_uncategorized++;
if (class->usage_mask & LOCKF_USED_IN_IRQ)
nr_irq_safe++;
if (class->usage_mask & LOCKF_ENABLED_IRQ)
nr_irq_unsafe++;
if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
nr_softirq_safe++;
if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
nr_softirq_unsafe++;
if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
nr_hardirq_safe++;
if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
nr_hardirq_unsafe++;
if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
nr_irq_read_safe++;
if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
nr_irq_read_unsafe++;
if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
nr_softirq_read_safe++;
if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
nr_softirq_read_unsafe++;
if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
nr_hardirq_read_safe++;
if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
nr_hardirq_read_unsafe++;
#ifdef CONFIG_PROVE_LOCKING
sum_forward_deps += lockdep_count_forward_deps(class);
#endif
}
#ifdef CONFIG_DEBUG_LOCKDEP
DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
#endif
seq_printf(m, " lock-classes: %11lu [max: %lu]\n",
nr_lock_classes, MAX_LOCKDEP_KEYS);
seq_printf(m, " direct dependencies: %11lu [max: %lu]\n",
nr_list_entries, MAX_LOCKDEP_ENTRIES);
seq_printf(m, " indirect dependencies: %11lu\n",
sum_forward_deps);
/*
* Total number of dependencies:
*
* All irq-safe locks may nest inside irq-unsafe locks,
* plus all the other known dependencies:
*/
seq_printf(m, " all direct dependencies: %11lu\n",
nr_irq_unsafe * nr_irq_safe +
nr_hardirq_unsafe * nr_hardirq_safe +
nr_list_entries);
/*
* Estimated factor between direct and indirect
* dependencies:
*/
if (nr_list_entries)
factor = sum_forward_deps / nr_list_entries;
#ifdef CONFIG_PROVE_LOCKING
seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
nr_lock_chains, MAX_LOCKDEP_CHAINS);
seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n",
nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
seq_printf(m, " in-hardirq chains: %11u\n",
nr_hardirq_chains);
seq_printf(m, " in-softirq chains: %11u\n",
nr_softirq_chains);
#endif
seq_printf(m, " in-process chains: %11u\n",
nr_process_chains);
seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n",
nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
seq_printf(m, " combined max dependencies: %11u\n",
(nr_hardirq_chains + 1) *
(nr_softirq_chains + 1) *
(nr_process_chains + 1)
);
seq_printf(m, " hardirq-safe locks: %11lu\n",
nr_hardirq_safe);
seq_printf(m, " hardirq-unsafe locks: %11lu\n",
nr_hardirq_unsafe);
seq_printf(m, " softirq-safe locks: %11lu\n",
nr_softirq_safe);
seq_printf(m, " softirq-unsafe locks: %11lu\n",
nr_softirq_unsafe);
seq_printf(m, " irq-safe locks: %11lu\n",
nr_irq_safe);
seq_printf(m, " irq-unsafe locks: %11lu\n",
nr_irq_unsafe);
seq_printf(m, " hardirq-read-safe locks: %11lu\n",
nr_hardirq_read_safe);
seq_printf(m, " hardirq-read-unsafe locks: %11lu\n",
nr_hardirq_read_unsafe);
seq_printf(m, " softirq-read-safe locks: %11lu\n",
nr_softirq_read_safe);
seq_printf(m, " softirq-read-unsafe locks: %11lu\n",
nr_softirq_read_unsafe);
seq_printf(m, " irq-read-safe locks: %11lu\n",
nr_irq_read_safe);
seq_printf(m, " irq-read-unsafe locks: %11lu\n",
nr_irq_read_unsafe);
seq_printf(m, " uncategorized locks: %11lu\n",
nr_uncategorized);
seq_printf(m, " unused locks: %11lu\n",
nr_unused);
seq_printf(m, " max locking depth: %11u\n",
max_lockdep_depth);
#ifdef CONFIG_PROVE_LOCKING
seq_printf(m, " max bfs queue depth: %11u\n",
max_bfs_queue_depth);
#endif
lockdep_stats_debug_show(m);
seq_printf(m, " debug_locks: %11u\n",
debug_locks);
return 0;
}
static int lockdep_stats_open(struct inode *inode, struct file *file)
{
return single_open(file, lockdep_stats_show, NULL);
}
static const struct file_operations proc_lockdep_stats_operations = {
.open = lockdep_stats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
#ifdef CONFIG_LOCK_STAT
struct lock_stat_data {
struct lock_class *class;
struct lock_class_stats stats;
};
struct lock_stat_seq {
struct lock_stat_data *iter_end;
struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
};
/*
* sort on absolute number of contentions
*/
static int lock_stat_cmp(const void *l, const void *r)
{
const struct lock_stat_data *dl = l, *dr = r;
unsigned long nl, nr;
nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
return nr - nl;
}
static void seq_line(struct seq_file *m, char c, int offset, int length)
{
int i;
for (i = 0; i < offset; i++)
seq_puts(m, " ");
for (i = 0; i < length; i++)
seq_printf(m, "%c", c);
seq_puts(m, "\n");
}
static void snprint_time(char *buf, size_t bufsiz, s64 nr)
{
s64 div;
s32 rem;
nr += 5; /* for display rounding */
div = div_s64_rem(nr, 1000, &rem);
snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
}
static void seq_time(struct seq_file *m, s64 time)
{
char num[15];
snprint_time(num, sizeof(num), time);
seq_printf(m, " %14s", num);
}
static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
{
seq_printf(m, "%14lu", lt->nr);
seq_time(m, lt->min);
seq_time(m, lt->max);
seq_time(m, lt->total);
}
static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
{
char name[39];
struct lock_class *class;
struct lock_class_stats *stats;
int i, namelen;
class = data->class;
stats = &data->stats;
namelen = 38;
if (class->name_version > 1)
namelen -= 2; /* XXX truncates versions > 9 */
if (class->subclass)
namelen -= 2;
if (!class->name) {
char str[KSYM_NAME_LEN];
const char *key_name;
key_name = __get_key_name(class->key, str);
snprintf(name, namelen, "%s", key_name);
} else {
snprintf(name, namelen, "%s", class->name);
}
namelen = strlen(name);
if (class->name_version > 1) {
snprintf(name+namelen, 3, "#%d", class->name_version);
namelen += 2;
}
if (class->subclass) {
snprintf(name+namelen, 3, "/%d", class->subclass);
namelen += 2;
}
if (stats->write_holdtime.nr) {
if (stats->read_holdtime.nr)
seq_printf(m, "%38s-W:", name);
else
seq_printf(m, "%40s:", name);
seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
seq_lock_time(m, &stats->write_waittime);
seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
seq_lock_time(m, &stats->write_holdtime);
seq_puts(m, "\n");
}
if (stats->read_holdtime.nr) {
seq_printf(m, "%38s-R:", name);
seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
seq_lock_time(m, &stats->read_waittime);
seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
seq_lock_time(m, &stats->read_holdtime);
seq_puts(m, "\n");
}
if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
return;
if (stats->read_holdtime.nr)
namelen += 2;
for (i = 0; i < LOCKSTAT_POINTS; i++) {
char sym[KSYM_SYMBOL_LEN];
char ip[32];
if (class->contention_point[i] == 0)
break;
if (!i)
seq_line(m, '-', 40-namelen, namelen);
sprint_symbol(sym, class->contention_point[i]);
snprintf(ip, sizeof(ip), "[<%p>]",
(void *)class->contention_point[i]);
seq_printf(m, "%40s %14lu %29s %s\n", name,
stats->contention_point[i],
ip, sym);
}
for (i = 0; i < LOCKSTAT_POINTS; i++) {
char sym[KSYM_SYMBOL_LEN];
char ip[32];
if (class->contending_point[i] == 0)
break;
if (!i)
seq_line(m, '-', 40-namelen, namelen);
sprint_symbol(sym, class->contending_point[i]);
snprintf(ip, sizeof(ip), "[<%p>]",
(void *)class->contending_point[i]);
seq_printf(m, "%40s %14lu %29s %s\n", name,
stats->contending_point[i],
ip, sym);
}
if (i) {
seq_puts(m, "\n");
seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
seq_puts(m, "\n");
}
}
static void seq_header(struct seq_file *m)
{
seq_printf(m, "lock_stat version 0.3\n");
if (unlikely(!debug_locks))
seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
"%14s %14s\n",
"class name",
"con-bounces",
"contentions",
"waittime-min",
"waittime-max",
"waittime-total",
"acq-bounces",
"acquisitions",
"holdtime-min",
"holdtime-max",
"holdtime-total");
seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
seq_printf(m, "\n");
}
static void *ls_start(struct seq_file *m, loff_t *pos)
{
struct lock_stat_seq *data = m->private;
struct lock_stat_data *iter;
if (*pos == 0)
return SEQ_START_TOKEN;
iter = data->stats + (*pos - 1);
if (iter >= data->iter_end)
iter = NULL;
return iter;
}
static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return ls_start(m, pos);
}
static void ls_stop(struct seq_file *m, void *v)
{
}
static int ls_show(struct seq_file *m, void *v)
{
if (v == SEQ_START_TOKEN)
seq_header(m);
else
seq_stats(m, v);
return 0;
}
static const struct seq_operations lockstat_ops = {
.start = ls_start,
.next = ls_next,
.stop = ls_stop,
.show = ls_show,
};
static int lock_stat_open(struct inode *inode, struct file *file)
{
int res;
struct lock_class *class;
struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
if (!data)
return -ENOMEM;
res = seq_open(file, &lockstat_ops);
if (!res) {
struct lock_stat_data *iter = data->stats;
struct seq_file *m = file->private_data;
list_for_each_entry(class, &all_lock_classes, lock_entry) {
iter->class = class;
iter->stats = lock_stats(class);
iter++;
}
data->iter_end = iter;
sort(data->stats, data->iter_end - data->stats,
sizeof(struct lock_stat_data),
lock_stat_cmp, NULL);
m->private = data;
} else
vfree(data);
return res;
}
static ssize_t lock_stat_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct lock_class *class;
char c;
if (count) {
if (get_user(c, buf))
return -EFAULT;
if (c != '0')
return count;
list_for_each_entry(class, &all_lock_classes, lock_entry)
clear_lock_stats(class);
}
return count;
}
static int lock_stat_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
vfree(seq->private);
return seq_release(inode, file);
}
static const struct file_operations proc_lock_stat_operations = {
.open = lock_stat_open,
.write = lock_stat_write,
.read = seq_read,
.llseek = seq_lseek,
.release = lock_stat_release,
};
#endif /* CONFIG_LOCK_STAT */
static int __init lockdep_proc_init(void)
{
proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
#ifdef CONFIG_PROVE_LOCKING
proc_create("lockdep_chains", S_IRUSR, NULL,
&proc_lockdep_chains_operations);
#endif
proc_create("lockdep_stats", S_IRUSR, NULL,
&proc_lockdep_stats_operations);
#ifdef CONFIG_LOCK_STAT
proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
&proc_lock_stat_operations);
#endif
return 0;
}
__initcall(lockdep_proc_init);