2023-05-24 17:11:22

by Osama Muhammad

Subject: [PATCH] smsdvb-debugfs.c: Fix error checking for debugfs_create_file

This patch fixes the error checking in smsdvb-debugfs.c in
debugfs_create_file. The correct way to check if an error occurred
is using 'IS_ERR_OR_NULL' inline function.

Signed-off-by: Osama Muhammad <[email protected]>
---
drivers/media/common/siano/smsdvb-debugfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/common/siano/smsdvb-debugfs.c b/drivers/media/common/siano/smsdvb-debugfs.c
index 8916bb644756..0f8750d7993c 100644
--- a/drivers/media/common/siano/smsdvb-debugfs.c
+++ b/drivers/media/common/siano/smsdvb-debugfs.c
@@ -469,7 +469,7 @@ int smsdvb_debugfs_create(struct smsdvb_client_t *client)

d = debugfs_create_file("stats", S_IRUGO | S_IWUSR, client->debugfs,
client, &debugfs_stats_ops);
- if (!d) {
+ if (IS_ERR_OR_NULL(d)) {
debugfs_remove(client->debugfs);
return -ENOMEM;
}
--
2.34.1

2023-05-26 11:08:47

by Mauro Carvalho Chehab

Subject: Re: [PATCH] smsdvb-debugfs.c: Fix error checking for debugfs_create_file

Em Wed, 24 May 2023 21:42:10 +0500
Osama Muhammad <[email protected]> escreveu:

> This patch fixes the error checking in smsdvb-debugfs.c in
> debugfs_create_file. The correct way to check if an error occurred
> is using 'IS_ERR_OR_NULL' inline function.
>
> Signed-off-by: Osama Muhammad <[email protected]>
> ---
> drivers/media/common/siano/smsdvb-debugfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/common/siano/smsdvb-debugfs.c b/drivers/media/common/siano/smsdvb-debugfs.c
> index 8916bb644756..0f8750d7993c 100644
> --- a/drivers/media/common/siano/smsdvb-debugfs.c
> +++ b/drivers/media/common/siano/smsdvb-debugfs.c
> @@ -469,7 +469,7 @@ int smsdvb_debugfs_create(struct smsdvb_client_t *client)
>
> d = debugfs_create_file("stats", S_IRUGO | S_IWUSR, client->debugfs,
> client, &debugfs_stats_ops);
> - if (!d) {
> + if (IS_ERR_OR_NULL(d)) {
> debugfs_remove(client->debugfs);
> return -ENOMEM;

if IS_ERR, it is probably better to return PTR_ERR(d).

So, please change it accordingly, returning -ENOMEM only on NULL, e. g.
something like (untested):

if (IS_ERR_OR_NULL(d)) {
debugfs_remove(client->debugfs);
if (!d)
return -ENOMEM;
return PTR_ERR(d);
}

Regards,
Mauro

2023-05-28 16:29:22

by Osama Muhammad

Subject: Re: [PATCH] smsdvb-debugfs.c: Fix error checking for debugfs_create_file

Hi,

After researching more into it I have come to know that the debugfs
API will not return null on error but an ERR_PTR. The modern wisdom
about it is to ignore the errors returned by the function as stated in
the comment above the function debugfs_create_file.

> * NOTE: it's expected that most callers should _ignore_ the errors returned
>* by this function. Other debugfs functions handle the fact that the "dentry"
>* passed to them could be an error and they don't crash in that case.
> * Drivers should generally work fine even if debugfs fails to init anyway.
Here is the link to comment :-
https://elixir.bootlin.com/linux/latest/source/fs/debugfs/inode.c#L451

Considering this, I will send the revision of the patch by removing
error checks. Please correct me if there are any concerns with this.

Thanks,
Osmten



On Fri, 26 May 2023 at 15:53, Mauro Carvalho Chehab <[email protected]> wrote:
>
> Em Wed, 24 May 2023 21:42:10 +0500
> Osama Muhammad <[email protected]> escreveu:
>
> > This patch fixes the error checking in smsdvb-debugfs.c in
> > debugfs_create_file. The correct way to check if an error occurred
> > is using 'IS_ERR_OR_NULL' inline function.
> >
> > Signed-off-by: Osama Muhammad <[email protected]>
> > ---
> > drivers/media/common/siano/smsdvb-debugfs.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/common/siano/smsdvb-debugfs.c b/drivers/media/common/siano/smsdvb-debugfs.c
> > index 8916bb644756..0f8750d7993c 100644
> > --- a/drivers/media/common/siano/smsdvb-debugfs.c
> > +++ b/drivers/media/common/siano/smsdvb-debugfs.c
> > @@ -469,7 +469,7 @@ int smsdvb_debugfs_create(struct smsdvb_client_t *client)
> >
> > d = debugfs_create_file("stats", S_IRUGO | S_IWUSR, client->debugfs,
> > client, &debugfs_stats_ops);
> > - if (!d) {
> > + if (IS_ERR_OR_NULL(d)) {
> > debugfs_remove(client->debugfs);
> > return -ENOMEM;
>
> if IS_ERR, it is probably better to return PTR_ERR(d).
>
> So, please change it accordingly, returning -ENOMEM only on NULL, e. g.
> something like (untested):
>
> if (IS_ERR_OR_NULL(d)) {
> debugfs_remove(client->debugfs);
> if (!d)
> return -ENOMEM;
> return PTR_ERR(d);
> }
>
> Regards,
> Mauro