linux-kernel - Re: [PATCH] x86/kaslr: remove useless code in mem_avoid

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Message-ID: <1566481427.5576.5.camel@lca.pw>
Date:   Thu, 22 Aug 2019 09:43:47 -0400
From:   Qian Cai <cai@....pw>
To:     Baoquan He <bhe@...hat.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/kaslr: remove useless code in mem_avoid_memmap

On Thu, 2019-08-22 at 21:26 +0800, Baoquan He wrote:
> On 08/22/19 at 08:32am, Qian Cai wrote:
> > MAX_MEMMAP_REGIONS is a macro that equal to 4. "i" is static local
> > variable that default to 0. The comparison "i >= MAX_MEMMAP_REGIONS"
> > will always be false.
> 
> Seems not true. mem_avoid_memmap() could be invoked many times if
> multiple memmap= added. It will carry the value accumulated from
> the past.

Ah, I am still a newbie in C after all those years. Sorry for the noise.

> 
> > 
> > Signed-off-by: Qian Cai <cai@....pw>
> > ---
> >  arch/x86/boot/compressed/kaslr.c | 3 ---
> >  1 file changed, 3 deletions(-)
> > 
> > diff --git a/arch/x86/boot/compressed/kaslr.c
> > b/arch/x86/boot/compressed/kaslr.c
> > index 2e53c056ba20..a4a5a88edb94 100644
> > --- a/arch/x86/boot/compressed/kaslr.c
> > +++ b/arch/x86/boot/compressed/kaslr.c
> > @@ -176,9 +176,6 @@ static void mem_avoid_memmap(char *str)
> >  {
> >  	static int i;
> >  
> > -	if (i >= MAX_MEMMAP_REGIONS)
> > -		return;
> > -
> >  	while (str && (i < MAX_MEMMAP_REGIONS)) {
> >  		int rc;
> >  		unsigned long long start, size;
> > -- 
> > 1.8.3.1
> >