linux-kernel - Re: [PATCH] cpu: microcode: Add comma to 0

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Message-ID: <20191127165025.GA10957@gmail.com>
Date:   Wed, 27 Nov 2019 17:50:25 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Jules Irenge <jbi.octave@...il.com>, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com,
        mingo@...hat.com
Subject: Re: [PATCH] cpu: microcode: Add comma to 0


* Borislav Petkov <bp@...en8.de> wrote:

> On Wed, Nov 27, 2019 at 07:54:36AM +0100, Ingo Molnar wrote:
> > 
> > * Jules Irenge <jbi.octave@...il.com> wrote:
> > 
> > > Add ","  after 0
> > > Because memory for the struct is being cleared
> > > and elements after "," are missing on purpose
> > >  as they are being cleared to
> > > 
> > > Recommended by Boris Petkov
> > > 
> > > Signed-off-by: Jules Irenge <jbi.octave@...il.com>
> > > ---
> > >  arch/x86/kernel/cpu/microcode/amd.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
> > > index a0e52bd00ecc..04ee649f4acb 100644
> > > --- a/arch/x86/kernel/cpu/microcode/amd.c
> > > +++ b/arch/x86/kernel/cpu/microcode/amd.c
> > > @@ -418,7 +418,7 @@ static int __apply_microcode_amd(struct microcode_amd *mc)
> > >  static bool
> > >  apply_microcode_early_amd(u32 cpuid_1_eax, void *ucode, size_t size, bool save_patch)
> > >  {
> > > -	struct cont_desc desc = { 0 };
> > > +	struct cont_desc desc = { 0, };
> > 
> > This is 100% unnecessary - " = { }" is enough of a structure initializer.
> 
> That was my initial thought but empty initializers are not ISO C
> compliant, I've been told.

Yeah, but the kernel isn't ISO C, and the hive mind has spoken in favor 
of the shortest variant:

  dagon:~/tip> git grep '= { }' | wc -l
  647

  dagon:~/tip> git grep '= { 0, }' | wc -l
  231

  dagon:~/tip> git grep '= { NULL, }' | wc -l
  38

:-)

Thanks,

	Ingo