linux-kernel - Re: [PATCH] timer: fix timer_migration to accept only 0 and 1

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Date:   Thu, 20 Apr 2017 14:53:26 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Myungho Jung <mhjungk@...il.com>
cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] timer: fix timer_migration to accept only 0 and 1

On Wed, 19 Apr 2017, Myungho Jung wrote:

> Error is not shown by setting invalid value to timer_migration. Valid
> values for timer_migration should be restricted to 0 and 1. Testcase for
> this bug is ltp/runpwtests06.

While I agree with the change, I disagree with the changelog. Where is the bug?

The timer code checks for timer_migration != 0 resp. == 0. So as long as
the value is != 0 it's enabled, if it's 0 it is disabled.

It's a correctness issue that we treat a sysctl which is basically a
boolean as such. Ideally we'd have: proc_doboolvec() for such cases and
convert all similar sysctls over to that.

Thanks,

	tglx