linux-kernel - Re: [PATCH] mtd: nuc900_nand: mark expected switch fall-through

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Date:   Thu, 19 Jul 2018 11:09:37 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Wan ZongShun <mcuos.com@...il.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: nuc900_nand: mark expected switch fall-through

Hi Miquel,

On 07/18/2018 03:03 AM, Miquel Raynal wrote:
> Hi Gustavo,
> 
> Prefix should be "mtd: rawnand: nuc900:"
> 

Oh OK. I'll fix it.

> "Gustavo A. R. Silva" <gustavo@...eddedor.com> wrote on Tue, 10 Jul
> 2018 08:29:02 -0500:
> 
>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>> where we are expecting to fall through.
>>
>> Addresses-Coverity-ID: 1471717 ("Missing break in switch")
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>> ---
>>  drivers/mtd/nand/raw/nuc900_nand.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/nand/raw/nuc900_nand.c b/drivers/mtd/nand/raw/nuc900_nand.c
>> index af5b32c9..53a9f6c 100644
>> --- a/drivers/mtd/nand/raw/nuc900_nand.c
>> +++ b/drivers/mtd/nand/raw/nuc900_nand.c
>> @@ -191,8 +191,9 @@ static void nuc900_nand_command_lp(struct mtd_info *mtd, unsigned int command,
>>  		return;
>>  
>>  	case NAND_CMD_READ0:
>> -
>>  		write_cmd_reg(nand, NAND_CMD_READSTART);
>> +		/* fall through */
> 
> Have you checked this is actually the right thing to do?
> 

Actually, no. My first impression was that due to the time this code has been
there, this might be a missing-break false positive. But, now that I'm double
checking, it may well be that this is an actual missing-break bug.

I can send a patch to fix this, but as I'm not familiar with the code, it'd be
of great help if someone could help me to verify this.

Thanks for the feedback.
--
Gustavo