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Date: Mon, 24 Feb 2020 04:04:42 -0600
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Subject: Re: [PATCH 1/2] powerpc/powernv: Treat an empty reboot string as
 default
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Cc: linuxppc-dev@lists.ozlabs.org, Oliver O'Halloran <oohall@gmail.com>
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On Mon, Feb 24, 2020 at 01:32:28PM +1100, Alexey Kardashevskiy wrote:
> On 17/02/2020 13:48, Oliver O'Halloran wrote:
> > Treat an empty reboot cmd string the same as a NULL string. This squashes a
> > spurious unsupported reboot message that sometimes gets out when using
> > xmon.

> > -		if (!cmd)
> > +		if (!cmd || !strlen(cmd))
> 
> nit: this does not matter here in practice but
> 
> if (!cmd || cmd[0] == '\0')
> 
> is faster (you do not care about the length anyway) and safer (@cmd can
> potentially be endless) ;)

No it isn't, this compiles to identical machine code.  (I tested with
GCC 9, and going back until 4.6 -- the generated code becomes
progressively worse (unrelated to this code, fwiw), but identical for
both cases all the time).


Segher