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Date:   Tue, 25 Jun 2019 09:42:14 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Frank Ch. Eigler" <fche@redhat.com>
Cc:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Jessica Yu <jeyu@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>, jikos@kernel.org,
        mbenes@suse.cz, Petr Mladek <pmladek@suse.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Robert Richter <rric@kernel.org>,
        rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        paulmck <paulmck@linux.ibm.com>,
        "Joel Fernandes, Google" <joel@joelfernandes.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        oprofile-list@lists.sf.net, netdev <netdev@vger.kernel.org>,
        bpf@vger.kernel.org
Subject: Re: [PATCH 2/3] module: Fix up module_notifier return values.
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On Mon, Jun 24, 2019 at 04:58:10PM -0400, Frank Ch. Eigler wrote:
> Hi -
> 
> > > While auditing all module notifiers I noticed a whole bunch of fail
> > > wrt the return value. Notifiers have a 'special' return semantics.
> 
> From peterz's comments, the patches, it's not obvious to me how one is
> to choose between 0 (NOTIFY_DONE) and 1 (NOTIFY_OK) in the case of a
> routine success.

I'm not sure either; what I think I choice was:

 - if I want to completely ignore the callback, use DONE (per the
   "Don't care" comment).

 - if we finished the notifier without error, use OK or
   notifier_from_errno(0).

But yes, its a bit of a shit interface.