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

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Message-ID: <CAK7LNAS=Vt__0E_WXzTB76gkJ6bUng9P1_wiWCi5aRLTP=1Www@mail.gmail.com>
Date:   Tue, 11 Jun 2019 06:09:55 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] kobject: return -ENOSPC when add_uevent_var() fails

On Tue, Jun 11, 2019 at 2:47 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> 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.



Didn't you see WARN() above the return code?
I rephrased the commit log for clarification in v2.

Thanks.


-- 
Best Regards
Masahiro Yamada