Re: [PATCH] locking/lock_events: no need to check return value of debugfs_create functions

From: Peter Zijlstra
Date: Mon Nov 09 2020 - 03:33:08 EST


On Sat, Nov 07, 2020 at 05:19:13PM +0800, Tiezhu Yang wrote:
> When calling debugfs functions, there is no need to ever check the
> return value. The function can work or not, but the code logic should
> never do something different based on this.

I strongly disagree and have told this to Greg before. Having half a
debug interface is weird at best, so upon failure we remove the whole
thing, which is consistent.

> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> ---
> kernel/locking/lock_events.c | 19 ++++---------------
> 1 file changed, 4 insertions(+), 15 deletions(-)
>
> diff --git a/kernel/locking/lock_events.c b/kernel/locking/lock_events.c
> index fa2c2f9..bac77a1 100644
> --- a/kernel/locking/lock_events.c
> +++ b/kernel/locking/lock_events.c
> @@ -146,9 +146,6 @@ static int __init init_lockevent_counts(void)
> struct dentry *d_counts = debugfs_create_dir(LOCK_EVENTS_DIR, NULL);
> int i;
>
> - if (!d_counts)
> - goto out;
> -
> /*
> * Create the debugfs files
> *
> @@ -159,21 +156,13 @@ static int __init init_lockevent_counts(void)
> for (i = 0; i < lockevent_num; i++) {
> if (skip_lockevent(lockevent_names[i]))
> continue;
> - if (!debugfs_create_file(lockevent_names[i], 0400, d_counts,
> - (void *)(long)i, &fops_lockevent))
> - goto fail_undo;
> + debugfs_create_file(lockevent_names[i], 0400, d_counts,
> + (void *)(long)i, &fops_lockevent);
> }
>
> - if (!debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200,
> - d_counts, (void *)(long)LOCKEVENT_reset_cnts,
> - &fops_lockevent))
> - goto fail_undo;
> + debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200, d_counts,
> + (void *)(long)LOCKEVENT_reset_cnts, &fops_lockevent);
>
> return 0;
> -fail_undo:
> - debugfs_remove_recursive(d_counts);
> -out:
> - pr_warn("Could not create '%s' debugfs entries\n", LOCK_EVENTS_DIR);
> - return -ENOMEM;
> }
> fs_initcall(init_lockevent_counts);
> --
> 2.1.0
>