Re: [PATCH v5] printk: Userspace format enumeration support

From: Chris Down <chris@chrisdown.name>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	John Ogness <john.ogness@linutronix.de>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Kees Cook <keescook@chromium.org>,
	kernel-team@fb.com
Subject: Re: [PATCH v5] printk: Userspace format enumeration support
Date: Wed, 10 Mar 2021 12:12:57 +0000	[thread overview]
Message-ID: <YEi3ySLkw3hZinnS@chrisdown.name> (raw)
In-Reply-To: <YEhsHELBM20f4MRE@kroah.com>

Greg Kroah-Hartman writes:
>On Wed, Mar 10, 2021 at 02:30:31AM +0000, Chris Down wrote:
>> +	ps->file = debugfs_create_file(pi_get_module_name(mod), 0444, dfs_index,
>> +				       ps, &dfs_index_fops);
>> +
>> +	if (IS_ERR(ps->file)) {
>> +		pi_sec_remove(mod);
>> +		return;
>> +	}
>
>No need to check this and try to clean up if there is a problem, just
>save the pointer off and call debugfs_remove() when you want to clean
>up.

Petr, what are your thoughts on this, since you requested the cleanup on 
debugfs failure? :-)

>Or better yet, no need to save anything, you can always look it up when
>you want to remove it, that will save you one pointer per module.

That's a good point, and with that maybe we can even do away with the pi_sec 
entirely then since that only leaves start/end pointers which we can calculate 
on demand from existing data.