linux-kernel - Re: [PATCH] kobject: return -ENOSPC when add_uevent

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Date:   Mon, 10 Jun 2019 19:45:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] kobject: return -ENOSPC when add_uevent_var() fails

On Wed, Jun 05, 2019 at 02:44:12AM +0900, Masahiro Yamada wrote:
> This function never attempts to allocate memory, so returning -ENOMEM
> looks weird to me. The reason of the failure is there is no more space
> in the given kobj_uevent_env structure.
> 
> No caller of this function relies on this functing returning a specific
> error code, so just change it to return -ENOSPC. The intended change,
> if any, is the error number displayed in log messages.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
> 
>  lib/kobject_uevent.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
> index 7998affa45d4..5ffd44bf4aad 100644
> --- a/lib/kobject_uevent.c
> +++ b/lib/kobject_uevent.c
> @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent);
>   * @env: environment buffer structure
>   * @format: printf format for the key=value pair
>   *
> - * Returns 0 if environment variable was added successfully or -ENOMEM
> + * Returns 0 if environment variable was added successfully or -ENOSPC
>   * if no space was available.
>   */
>  int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
> @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
>  
>  	if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
>  		WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
> -		return -ENOMEM;
> +		return -ENOSPC;

As Rafael says, changing this for no good reason is not a good idea,
sorry.  Let's live with it as-is unless you can show some place where
this specific error value is causing problems.

thanks,

greg k-h