linux-kernel - Re: [PATCH] firmware: dmi_scan: Drop dmi

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Date:   Mon, 25 Sep 2017 11:26:44 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jean Delvare <jdelvare@...e.de>
Cc:     Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] firmware: dmi_scan: Drop dmi_initialized

On Mon, Sep 25, 2017 at 11:00:11AM +0200, Jean Delvare wrote:
> Then we have that in common. While reading the code and its history, I
> was worried that the justification to add this warning in the first
> place was technically weak. Not every coding error must automatically
> translate to a patch to make the code robust against said error.
> Sometimes you just have to admit that you did not pay attention as you
> should have, fix your mistake, possibly document it for others, and
> move on. Otherwise we end up with slow bloated code.

That WARN_ON() is a form of documentation.

And if you care about performance for your code path, hide it under some
CONFIG_*_DEBUG, but in general WARN_ON() isn't terribly expensive
(depending entirely on the complexity of the condition of course).