From: Robert Richter <rric@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Frank Ch. Eigler" <fche@redhat.com>,
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>,
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.
Date: Thu, 4 Jul 2019 14:48:27 +0200 [thread overview]
Message-ID: <20190704124827.hsuse5g3x5bgdgb3@rric.localdomain> (raw)
In-Reply-To: <20190625074214.GR3436@hirez.programming.kicks-ass.net>
On 25.06.19 09:42:14, Peter Zijlstra wrote:
> On Mon, Jun 24, 2019 at 04:58:10PM -0400, Frank Ch. Eigler wrote:
> > 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.
It looks like it was rarely used in earlier kernels as some sort of
error detection for the notifier calls, e.g.:
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c-int profile_handoff_task(struct task_struct * task)
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c-{
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c- int ret;
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c- read_lock(&handoff_lock);
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c- ret = notifier_call_chain(&task_free_notifier, 0, task);
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c- read_unlock(&handoff_lock);
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c: return (ret == NOTIFY_OK) ? 1 : 0;
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2:kernel/profile.c-}
So NOTIFY_OK was used to state there is no error, while NOTIFY_DONE
says the notifier was executed and there might have been errors. The
caller may distinguish the results then.
-Robert
next prev parent reply other threads:[~2019-07-04 12:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 9:18 [PATCH 0/3] Propagate module notifier errors Peter Zijlstra
2019-06-24 9:18 ` [PATCH 1/3] notifier: Fix broken error handling pattern Peter Zijlstra
2019-06-24 22:21 ` Josh Poimboeuf
2019-06-25 7:38 ` Peter Zijlstra
2019-06-25 12:13 ` Josh Poimboeuf
2019-06-25 13:22 ` Peter Zijlstra
2019-06-24 9:18 ` [PATCH 2/3] module: Fix up module_notifier return values Peter Zijlstra
2019-06-24 14:01 ` Mathieu Desnoyers
2019-06-24 15:52 ` Joel Fernandes
2019-06-24 17:50 ` Mathieu Desnoyers
2019-06-24 20:58 ` Frank Ch. Eigler
2019-06-25 7:42 ` Peter Zijlstra
2019-07-04 12:48 ` Robert Richter [this message]
2019-07-04 12:34 ` Robert Richter
2019-06-24 9:18 ` [PATCH 3/3] module: Properly propagate MODULE_STATE_COMING failure Peter Zijlstra
2019-06-24 11:07 ` Peter Zijlstra
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