linux/kernel/locking/lockdep_proc.c
Bart Van Assche 8c779229d0 locking/lockdep: Report more stack trace statistics
Report the number of stack traces and the number of stack trace hash
chains. These two numbers are useful because these allow to estimate
the number of stack trace hash collisions.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190722182443.216015-5-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-25 15:43:28 +02:00

672 lines
17 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* 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
*
* Code for /proc/lockdep and /proc/lockdep_stats:
*
*/
#include <linux/export.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 <linux/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[KSYM_NAME_LEN];
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", debug_class_ops_read(class));
#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,
};
#ifdef CONFIG_PROVE_LOCKING
static void *lc_start(struct seq_file *m, loff_t *pos)
{
if (*pos < 0)
return NULL;
if (*pos == 0)
return SEQ_START_TOKEN;
return lock_chains + (*pos - 1);
}
static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
{
*pos = lockdep_next_lockchain(*pos - 1) + 1;
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) {
if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
seq_printf(m, "(buggered) ");
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,
};
#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, " redundant checks: %11llu\n",
debug_atomic_read(nr_redundant_checks));
seq_printf(m, " redundant links: %11llu\n",
debug_atomic_read(nr_redundant));
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)
{
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;
#ifdef CONFIG_PROVE_LOCKING
struct lock_class *class;
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++;
sum_forward_deps += lockdep_count_forward_deps(class);
}
#ifdef CONFIG_DEBUG_LOCKDEP
DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
#endif
#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);
#ifdef CONFIG_PROVE_LOCKING
seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
lock_chain_count(), 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);
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
seq_printf(m, " number of stack traces: %llu\n",
lockdep_stack_trace_count());
seq_printf(m, " number of stack hash chains: %llu\n",
lockdep_stack_hash_count());
#endif
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;
}
#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);
seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
}
static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
{
const struct lockdep_subclass_key *ckey;
struct lock_class_stats *stats;
struct lock_class *class;
const char *cname;
int i, namelen;
char name[39];
class = data->class;
stats = &data->stats;
namelen = 38;
if (class->name_version > 1)
namelen -= 2; /* XXX truncates versions > 9 */
if (class->subclass)
namelen -= 2;
rcu_read_lock_sched();
cname = rcu_dereference_sched(class->name);
ckey = rcu_dereference_sched(class->key);
if (!cname && !ckey) {
rcu_read_unlock_sched();
return;
} else if (!cname) {
char str[KSYM_NAME_LEN];
const char *key_name;
key_name = __get_key_name(ckey, str);
snprintf(name, namelen, "%s", key_name);
} else {
snprintf(name, namelen, "%s", cname);
}
rcu_read_unlock_sched();
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 ip[32];
if (class->contention_point[i] == 0)
break;
if (!i)
seq_line(m, '-', 40-namelen, namelen);
snprintf(ip, sizeof(ip), "[<%p>]",
(void *)class->contention_point[i]);
seq_printf(m, "%40s %14lu %29s %pS\n",
name, stats->contention_point[i],
ip, (void *)class->contention_point[i]);
}
for (i = 0; i < LOCKSTAT_POINTS; i++) {
char ip[32];
if (class->contending_point[i] == 0)
break;
if (!i)
seq_line(m, '-', 40-namelen, namelen);
snprintf(ip, sizeof(ip), "[<%p>]",
(void *)class->contending_point[i]);
seq_printf(m, "%40s %14lu %29s %pS\n",
name, stats->contending_point[i],
ip, (void *)class->contending_point[i]);
}
if (i) {
seq_puts(m, "\n");
seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
seq_puts(m, "\n");
}
}
static void seq_header(struct seq_file *m)
{
seq_puts(m, "lock_stat version 0.4\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 + 12 * (14 + 1));
seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
"%14s %14s\n",
"class name",
"con-bounces",
"contentions",
"waittime-min",
"waittime-max",
"waittime-total",
"waittime-avg",
"acq-bounces",
"acquisitions",
"holdtime-min",
"holdtime-max",
"holdtime-total",
"holdtime-avg");
seq_line(m, '-', 0, 40 + 1 + 12 * (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_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
#ifdef CONFIG_PROVE_LOCKING
proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
#endif
proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
#ifdef CONFIG_LOCK_STAT
proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
&proc_lock_stat_operations);
#endif
return 0;
}
__initcall(lockdep_proc_init);