Messages in this thread Patch in this message | | | From | Xiongwei Song <> | Subject | [PATCH v2] locking/lockdep: Fix meaningless usages output of lock classes | Date | Mon, 28 Jun 2021 23:17:08 +0800 |
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From: Xiongwei Song <sxwjean@gmail.com>
When enabling CONFIG_LOCK_STAT, then CONFIG_LOCKDEP is forcedly enabled. We can get output from /proc/lockdep, which currently includes usages of lock classes. But the usages are meaningless, see the output below:
/ # cat /proc/lockdep all lock classes: ffffffff9af63350 ....: cgroup_mutex
ffffffff9af54eb8 ....: (console_sem).lock
ffffffff9af54e60 ....: console_lock
ffffffff9ae74c38 ....: console_owner_lock
ffffffff9ae74c80 ....: console_owner
ffffffff9ae66e60 ....: cpu_hotplug_lock
Only one usage context for each lock, this is because each usage is only changed in mark_lock() that is in CONFIG_PROVE_LOCKING defined section, however in the test situation, it's not.
The fix is to move the usages reading and seq_print from CONFIG_PROVE_LOCKING undefined setcion to its defined section. Also, locks_after list of lock_class is empty when CONFIG_PROVE_LOCKING undefined, so do the same thing as what have done for usages of lock classes.
Signed-off-by: Xiongwei Song <sxwjean@gmail.com> --- kernel/locking/lockdep_proc.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index 806978314496..a1ec2652d492 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -70,23 +70,25 @@ static int l_show(struct seq_file *m, void *v) #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 + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { + seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class)); + seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class)); - get_usage_chars(class, usage); - seq_printf(m, " %s", usage); + 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"); + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { + 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"); -- 2.30.2
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