Messages in this thread | | | From | Xiongwei Song <> | Date | Tue, 29 Jun 2021 10:52:41 +0800 | Subject | Re: [PATCH v2] locking/lockdep: Fix meaningless usages output of lock classes |
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On Tue, Jun 29, 2021 at 5:17 AM Waiman Long <llong@redhat.com> wrote: > > On 6/28/21 11:17 AM, Xiongwei Song wrote: > > 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. > With this patch, CONFIG_LOCKDEP without CONFIG_PROVE_LOCKING will make > /proc/lockdep displays just the list of lock classes with their > associated lock keys. I think it is worth explicitly saying that in the > commit log.
Make sense. Will update.
> > 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"); > > Maybe you can remove the blank lines in this case by moving the last > seq_puts() inside the if loop. The blank lines are not really needed > without the associated locks_after information.
Yeah, I agree. Thank you.
Regards, Xiongwei
> Cheers, > Longman >
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