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

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Message-ID: <ad24ee3a-0212-0762-87c4-9a93faecbeef@embeddedor.com>
Date:   Thu, 19 Jul 2018 11:20:08 -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. Thanks.

> "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 long time this code has been there,
this might be a missing-break-in-switch false positive. But, due to your comments and a
double check at the code, it may well be that this is an actual bug and that a return
statement should be added after calling write_cmd_reg. Similar to the cases above.

I can send a patch to fix this, but it would be great if someone could help me to verify
this first. :)

Thanks for the feedback!
--
Gustavo