linux-kernel - Re: [PATCH v2] mtd: rawnand: mark expected switch fall-throughs

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Message-ID: <20190412001009.2db358b7@xps13>
Date:   Fri, 12 Apr 2019 00:10:09 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Kyungmin Park <kyungmin.park@...sung.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Wan ZongShun <mcuos.com@...il.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2] mtd: rawnand: mark expected switch fall-throughs

Hi Gustavo,

"Gustavo A. R. Silva" <gustavo@...eddedor.com> wrote on Thu, 11 Apr
2019 13:30:31 -0500:

> Hi Miquel,
> 
> On 2/5/19 6:55 AM, Miquel Raynal wrote:
> [..]
> >> @@ -3280,12 +3280,14 @@ static void onenand_check_features(struct mtd_info *mtd)
> >>  			if ((this->version_id & 0xf) == 0xe)
> >>  				this->options |= ONENAND_HAS_NOP_1;
> >>  		}
> >> +		/* fall through */
> >>  
> >>  	case ONENAND_DEVICE_DENSITY_2Gb:
> >>  		/* 2Gb DDP does not have 2 plane */
> >>  		if (!ONENAND_IS_DDP(this))
> >>  			this->options |= ONENAND_HAS_2PLANE;
> >>  		this->options |= ONENAND_HAS_UNLOCK_ALL;
> >> +		/* fall through */  
> > 
> > This looks strange.
> > 
> > In ONENAND_DEVICE_DENSITY_2Gb:
> > ONENAND_HAS_UNLOCK_ALL is set unconditionally.
> > 
> > But then, under ONENAND_DEVICE_DENSITY_1Gb, the same option is set only
> > if process is evaluated to true.
> > 
> > Same problem with ONENAND_HAS_2PLANE:
> > - it is set in ONENAND_DEVICE_DENSITY_4Gb only if ONENAND_IS_DDP()
> > - it is unset in ONENAND_DEVICE_DENSITY_2Gb only if !ONENAND_IS_DDP()
> > 
> > Maybe this portion should be reworked because I am unsure if this is a
> > missing fall through or a bug.
> >   
> 
> I wonder if you had the chance to take a look into this piece of code.
> 
> Thanks
> --
> Gustavo

What do you mean?


Thanks,
Miquèl