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

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Date:   Thu, 11 Apr 2019 13:30:31 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Miquel Raynal <miquel.raynal@...tlin.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 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