linux-kernel - Re: [PATCH] FDDI: defxx: simplify if-if to if-else

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Message-ID: <YmaO0PEZS6mjsHhO@lunn.ch>
Date:   Mon, 25 Apr 2022 14:06:40 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     "Maciej W. Rozycki" <macro@...am.me.uk>
Cc:     Wan Jiabing <wanjiabing@...o.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kael_w@...h.net
Subject: Re: [PATCH] FDDI: defxx: simplify if-if to if-else

On Mon, Apr 25, 2022 at 12:26:10AM +0100, Maciej W. Rozycki wrote:
> On Mon, 25 Apr 2022, Andrew Lunn wrote:
> 
> > >  NAK.  The first conditional optionally sets `bp->mmio = false', which 
> > > changes the value of `dfx_use_mmio' in some configurations:
> > > 
> > > #if defined(CONFIG_EISA) || defined(CONFIG_PCI)
> > > #define dfx_use_mmio bp->mmio
> > > #else
> > > #define dfx_use_mmio true
> > > #endif
> > 
> > Which is just asking for trouble like this.
> > 
> > Could i suggest dfx_use_mmio is changed to DFX_USE_MMIO to give a hint
> > something horrible is going on.
> 
>  There's legacy behind it, `dfx_use_mmio' used to be a proper variable and 
> references were retained not to obfuscate the changes that ultimately led 
> to the current arrangement.  I guess at this stage it could be changed to 
> a function-like macro or a static inline function taking `bp' as the 
> argument.

Yes, something like that would be good.

> > It probably won't stop the robots finding this if (x) if (!x), but
> > there is a chance the robot drivers will wonder why it is upper case.
> 
>  Well, blindly relying on automation is bound to cause trouble.

Unfortunately, there are a number of bot drivers who do blindly rely
on automation. We have had to undo the same broken bot driven changes
a few times, and ended up adding extra comments to catch the eye of
the bot drivers.

    Andrew