[PATCH] powerpc/powernv: use appropiate error code

[PATCH] powerpc/powernv: use appropiate error code

[mirimmad]

From: Immad Mir <mirimmad17@gmail.com>

-1 is not a valid error code. This patch replaces it with -EPERM.

Signed-off-by: Immad Mir <mirimmad17@gmail.com>
---
 arch/powerpc/platforms/powernv/opal-xscom.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal-xscom.c b/arch/powerpc/platforms/powernv/opal-xscom.c
index 262cd6fac..ce4b089dd 100644
--- a/arch/powerpc/platforms/powernv/opal-xscom.c
+++ b/arch/powerpc/platforms/powernv/opal-xscom.c
@@ -171,7 +171,7 @@ static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
 	if (IS_ERR(dir)) {
 		kfree(ent->path.data);
 		kfree(ent);
-		return -1;
+		return -EPERM;
 	}

 	debugfs_create_blob("devspec", 0400, dir, &ent->path);
@@ -191,7 +191,7 @@ static int scom_debug_init(void)

 	root = debugfs_create_dir("scom", arch_debugfs_dir);
 	if (IS_ERR(root))
-		return -1;
+		return -EPERM;

 	rc = 0;
 	for_each_node_with_property(dn, "scom-controller") {
--
2.40.0

Re: [PATCH] powerpc/powernv: use appropiate error code

[Christophe Leroy]

Le 01/09/2023 à 19:19, mirimmad@outlook.com a écrit :
> [Vous ne recevez pas souvent de courriers de mirimmad@outlook.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> From: Immad Mir <mirimmad17@gmail.com>
> 
> -1 is not a valid error code. This patch replaces it with -EPERM.

Can you explain how it will work ?
In scom_debug_init() rc is built by oring the value returned by 
scom_debug_init_one().
What will be the result when oring some valid values with -EPERM ?
It was working well with -1 because when you or -1 with anything you get 
-1 as result. But with your change I don't think it will work.

Christophe

> 
> Signed-off-by: Immad Mir <mirimmad17@gmail.com>
> ---
>   arch/powerpc/platforms/powernv/opal-xscom.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/opal-xscom.c b/arch/powerpc/platforms/powernv/opal-xscom.c
> index 262cd6fac..ce4b089dd 100644
> --- a/arch/powerpc/platforms/powernv/opal-xscom.c
> +++ b/arch/powerpc/platforms/powernv/opal-xscom.c
> @@ -171,7 +171,7 @@ static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
>          if (IS_ERR(dir)) {
>                  kfree(ent->path.data);
>                  kfree(ent);
> -               return -1;
> +               return -EPERM;
>          }
> 
>          debugfs_create_blob("devspec", 0400, dir, &ent->path);
> @@ -191,7 +191,7 @@ static int scom_debug_init(void)
> 
>          root = debugfs_create_dir("scom", arch_debugfs_dir);
>          if (IS_ERR(root))
> -               return -1;
> +               return -EPERM;
> 
>          rc = 0;
>          for_each_node_with_property(dn, "scom-controller") {
> --
> 2.40.0
> 

Re: [PATCH] powerpc/powernv: use appropiate error code

[Immad Mir]

On 01/09/23 11:10 pm, Christophe Leroy wrote:
>
> Le 01/09/2023 à 19:19, mirimmad@outlook.com a écrit :
>> [Vous ne recevez pas souvent de courriers de mirimmad@outlook.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>
>> From: Immad Mir <mirimmad17@gmail.com>
>>
>> -1 is not a valid error code. This patch replaces it with -EPERM.
> Can you explain how it will work ?
> In scom_debug_init() rc is built by oring the value returned by
> scom_debug_init_one().
> What will be the result when oring some valid values with -EPERM ?
> It was working well with -1 because when you or -1 with anything you get
> -1 as result. But with your change I don't think it will work.

But Isn't EPERM defined to be 1.


Immad.

>
> Christophe
>
>> Signed-off-by: Immad Mir <mirimmad17@gmail.com>
>> ---
>>    arch/powerpc/platforms/powernv/opal-xscom.c | 4 ++--
>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/opal-xscom.c b/arch/powerpc/platforms/powernv/opal-xscom.c
>> index 262cd6fac..ce4b089dd 100644
>> --- a/arch/powerpc/platforms/powernv/opal-xscom.c
>> +++ b/arch/powerpc/platforms/powernv/opal-xscom.c
>> @@ -171,7 +171,7 @@ static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
>>           if (IS_ERR(dir)) {
>>                   kfree(ent->path.data);
>>                   kfree(ent);
>> -               return -1;
>> +               return -EPERM;
>>           }
>>
>>           debugfs_create_blob("devspec", 0400, dir, &ent->path);
>> @@ -191,7 +191,7 @@ static int scom_debug_init(void)
>>
>>           root = debugfs_create_dir("scom", arch_debugfs_dir);
>>           if (IS_ERR(root))
>> -               return -1;
>> +               return -EPERM;
>>
>>           rc = 0;
>>           for_each_node_with_property(dn, "scom-controller") {
>> --
>> 2.40.0
>>

Re: [PATCH] powerpc/powernv: use appropiate error code

[Immad Mir]

On 01/09/23 11:10 pm, Christophe Leroy wrote:
>
> Le 01/09/2023 à 19:19, mirimmad@outlook.com a écrit :
>> [Vous ne recevez pas souvent de courriers de mirimmad@outlook.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>
>> From: Immad Mir <mirimmad17@gmail.com>
>>
>> -1 is not a valid error code. This patch replaces it with -EPERM.
> Can you explain how it will work ?
> In scom_debug_init() rc is built by oring the value returned by
> scom_debug_init_one().
> What will be the result when oring some valid values with -EPERM ?
> It was working well with -1 because when you or -1 with anything you get
> -1 as result. But with your change I don't think it will work.


if EPERM is not always necessarily equal to 1, we can put a check in 
scom_debug_init before returning rc. If it is less than 1 (because AFAIK 
or-ring with negative number results back into the same negative number) 
we set rc equal to -1.

Immad.

>
> Christophe
>
>> Signed-off-by: Immad Mir <mirimmad17@gmail.com>
>> ---
>>    arch/powerpc/platforms/powernv/opal-xscom.c | 4 ++--
>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/opal-xscom.c b/arch/powerpc/platforms/powernv/opal-xscom.c
>> index 262cd6fac..ce4b089dd 100644
>> --- a/arch/powerpc/platforms/powernv/opal-xscom.c
>> +++ b/arch/powerpc/platforms/powernv/opal-xscom.c
>> @@ -171,7 +171,7 @@ static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
>>           if (IS_ERR(dir)) {
>>                   kfree(ent->path.data);
>>                   kfree(ent);
>> -               return -1;
>> +               return -EPERM;
>>           }
>>
>>           debugfs_create_blob("devspec", 0400, dir, &ent->path);
>> @@ -191,7 +191,7 @@ static int scom_debug_init(void)
>>
>>           root = debugfs_create_dir("scom", arch_debugfs_dir);
>>           if (IS_ERR(root))
>> -               return -1;
>> +               return -EPERM;
>>
>>           rc = 0;
>>           for_each_node_with_property(dn, "scom-controller") {
>> --
>> 2.40.0
>>

Re: [PATCH] powerpc/powernv: use appropiate error code

[Christophe Leroy]

Le 01/09/2023 à 20:03, Immad Mir a écrit :
> 
> On 01/09/23 11:10 pm, Christophe Leroy wrote:
>>
>> Le 01/09/2023 à 19:19, mirimmad@outlook.com a écrit :
>>> [Vous ne recevez pas souvent de courriers de mirimmad@outlook.com. 
>>> Découvrez pourquoi ceci est important à 
>>> https://aka.ms/LearnAboutSenderIdentification ]
>>>
>>> From: Immad Mir <mirimmad17@gmail.com>
>>>
>>> -1 is not a valid error code. This patch replaces it with -EPERM.
>> Can you explain how it will work ?
>> In scom_debug_init() rc is built by oring the value returned by
>> scom_debug_init_one().
>> What will be the result when oring some valid values with -EPERM ?
>> It was working well with -1 because when you or -1 with anything you get
>> -1 as result. But with your change I don't think it will work.
> 
> 
> if EPERM is not always necessarily equal to 1, we can put a check in 
> scom_debug_init before returning rc. If it is less than 1 (because AFAIK 
> or-ring with negative number results back into the same negative number) 
> we set rc equal to -1.
> 

The point is that EPERM is 1 by coincidence, the intention here is not 
to return -EPERM but really -1, so by changing this you just make the 
code harded to understand and maintain.

Christophe