linux-kernel - Re: [PATCH] android: binder: print error message on failure of creating proc file

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Message-ID: <2024071241-entail-icing-58cf@gregkh>
Date: Fri, 12 Jul 2024 09:19:02 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Leesoo Ahn <lsahn@...eel.net>
Cc: Carlos Llamas <cmllamas@...gle.com>, Leesoo Ahn <lsahn@...akecorp.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Christian Brauner <brauner@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] android: binder: print error message on failure of
 creating proc file

On Fri, Jul 12, 2024 at 03:52:32PM +0900, Leesoo Ahn wrote:
> 2024년 7월 12일 (금) 오후 1:01, Carlos Llamas <cmllamas@...gle.com>님이 작성:
> >
> > On Fri, Jul 12, 2024 at 12:21:40PM +0900, Leesoo Ahn wrote:
> > > It better prints out an error message to give more information if
> > > calling debugfs_create_file() is failure and the return value has an
> > > error code.
> > >
> > > Signed-off-by: Leesoo Ahn <lsahn@...eel.net>
> > > ---
> >
> > What are you trying to fix? My understanding is that users of the
> > debugfs API can safely ignore any errors and move on. IMO it doesn't
> > make sense to add this without a real reason.
> 
> What I was trying to say, users would predict that a file under
> debugfs will be created while they are opening a binder device. But if
> it failed for some reason without any debug message, they would get
> confused that the file doesn't exist and have no clue what happened
> without a message.

And that's fine, again, the kernel does not care if debugfs is working
or not.  It's just a debugging help, it does not affect the normal
operation of a system at all, and as such, userspace can't rely on it
being present for any functionality other than debugging issues that
might happen at times.

thanks,

greg k-h