linux-kernel - Re: [PATCH v2 06/10] EDAC/ghes: Remove local variable rdr_mask in ghes_edac

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Date:   Mon, 27 Apr 2020 10:24:08 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Robert Richter <rrichter@...vell.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        James Morse <james.morse@....com>,
        Aristeu Rozanski <aris@...hat.com>,
        Matthias Brugger <mbrugger@...e.com>,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/10] EDAC/ghes: Remove local variable rdr_mask in
 ghes_edac_dmidecode()

On Mon, Apr 27, 2020 at 09:08:02AM +0200, Borislav Petkov wrote:
> >  			if (entry->type_detail & BIT(6))
> >  				dimm->mtype = MEM_RMBS;
> > -			else if ((entry->type_detail & rdr_mask) == rdr_mask)
> > +			else if ((entry->type_detail & BIT(7)) &&
> > +				 (entry->type_detail & BIT(13)))
> 
> Well, "checks some bits" doesn't make it more telling than checking a
> descriptive name like "rdr_mask" but ok, since we're assigning MEM_RDR
> here, it is still clear what the check does.
> 
> Btw, please write it like this:
> 
> 			else if (entry->type_detail & (BIT(7) | BIT(13)))

That isn't the same. The previous version checked that BOTH bits
7 and 13 were set. Your version checks for either bit.

Looks like the original with the local variable was checking for both
bits set.

-Tony