Re: [PATCH] LoongArch: Delete debugfs checking

From: WANG Xuerui
Date: Wed Jun 28 2023 - 10:23:06 EST


Hi,

On 2023/6/20 16:06, Dan Carpenter wrote:
Debugfs functions are not supposed to be checked for errors. This
is sort of unusual but it is described in the comments for the
debugfs_create_dir() function. Also debugfs_create_dir() can never
return NULL.

Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
I spotted this code because I was looking at patches which were sent
to stable but without a Fixes tag. The correct way of checking for
error pointers is not IS_ERR_OR_NULL(), it's IS_ERR(). When a function
returns both error pointers and NULL, the NULL should be treated as a
special kind of success. Please see my blog for more details.

https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/

I have not included a Fixes tag here, because it's not really a bug fix,
it's just a clean up.

Thanks for the patch and sorry for the late review. I didn't notice this back then (just recovering from covid around that time) but since loongarch-next isn't tagged yet I think the patch could make it this cycle. (Somehow Huacai didn't see the mail either, weird...)


arch/loongarch/kernel/unaligned.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/arch/loongarch/kernel/unaligned.c b/arch/loongarch/kernel/unaligned.c
index 85fae3d2d71a..3abf163dda05 100644
--- a/arch/loongarch/kernel/unaligned.c
+++ b/arch/loongarch/kernel/unaligned.c
@@ -485,8 +485,6 @@ static int __init debugfs_unaligned(void)
struct dentry *d;
d = debugfs_create_dir("loongarch", NULL);
- if (IS_ERR_OR_NULL(d))
- return -ENOMEM;
debugfs_create_u32("unaligned_instructions_user",
S_IRUGO, d, &unaligned_instructions_user);

Trivial enough, thanks!

Reviewed-by: WANG Xuerui <git@xxxxxxxxxx>

--
WANG "xen0n" Xuerui

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