linux-kernel - Re: [PATCH v2] proc/sysctl: don't return ENOMEM on lookup when a table is unregistering

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Message-ID: <20181214014539.GO2217@ZenIV.linux.org.uk>
Date:   Fri, 14 Dec 2018 01:45:40 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Ivan Delalande <colona@...sta.com>
Cc:     Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2] proc/sysctl: don't return ENOMEM on lookup when a
 table is unregistering

On Thu, Dec 13, 2018 at 03:20:52PM -0800, Ivan Delalande wrote:

> @@ -474,7 +474,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
>  	if (unlikely(head->unregistering)) {
>  		spin_unlock(&sysctl_lock);
>  		iput(inode);
> -		inode = NULL;
> +		inode = ERR_PTR(-ENOENT);
>  		goto out;
>  	}

Applied, with one modification: if you look at the target of that goto,
you'll see
out:
        return inode;
so this place should be simply
 		spin_unlock(&sysctl_lock);
 		iput(inode);
		return ERR_PTR(-ENOENT);
	}

That way the label becomes unused and goes away.