linux-kernel - Re: [PATCH 2/2] arch/x86: Fix sparse warning symbol not declared

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Date:   Sun, 12 Feb 2017 12:06:47 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Tobin C. Harding" <me@...in.cc>
cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: Re: [PATCH 2/2] arch/x86: Fix sparse warning symbol not declared

On Sun, 12 Feb 2017, Tobin C. Harding wrote:

> This patch adds function declaration in order to quiet sparse symbol
> not declared warning.

Same comment vs. 'This patch' as before. Hint, we already know that this is
a patch, otherwise it would be mislabeled.

> 
> Signed-off-by: Tobin C. Harding <me@...in.cc>
> ---
> 
> Unsure why adding declaration quiets sparse.

Because sparse finds a declaration before the definition.

> This may not be the correct solution.

Right, it's not.

> Only testing done is building and booting kernel.  Since 'purgatory' is
> called from assembler and does not need forward declaration the only
> advantage to this patch seems to be to save the next newbie from
> investigating the sparse warning.

Well, yes. But just quietening a checker by slapping a pointless forward
declaration into the code is not pretty either. A smarter checker might
catch that.

The proper solution is to have a local include file 'purgatory.h' and put
the declaration there. Include it in both files even if that's not required
for the ASM file. But that documents, that the function is used outside of
purgatory.c

Thanks,

	tglx