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Subject: Re: [PATCH] block: t10-pi: fix -Wswitch warning
To:     Nathan Chancellor <natechancellor@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>
CC:     Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
        <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <clang-built-linux@googlegroups.com>
References: <20190919135725.1287963-1-arnd@arndb.de>
 <20190920060503.GA130425@archlinux-threadripper>
From:   Max Gurtovoy <maxg@mellanox.com>
Message-ID: <f279edcb-1d54-2333-8aa1-1af8c91bbc95@mellanox.com>
Date:   Sun, 22 Sep 2019 01:05:42 +0300
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On 9/20/2019 9:05 AM, Nathan Chancellor wrote:
> On Thu, Sep 19, 2019 at 03:57:19PM +0200, Arnd Bergmann wrote:
>> Changing the switch() statement to symbolic constants made
>> the compiler (at least clang-9, did not check gcc) notice that
>> there is one enum value that is not handled here:
>>
>> block/t10-pi.c:62:11: error: enumeration value 'T10_PI_TYPE0_PROTECTION' not handled in switch [-Werror,-Wswitch]
>>
>> Add another case for the missing value and do nothing there
>> based on the assumption that the code was working correctly
>> already.
>>
>> Fixes: 9b2061b1a262 ("block: use symbolic constants for t10_pi type")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>>   block/t10-pi.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/block/t10-pi.c b/block/t10-pi.c
>> index 0c0120a672f9..055fac923946 100644
>> --- a/block/t10-pi.c
>> +++ b/block/t10-pi.c
>> @@ -60,6 +60,8 @@ static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
>>   		__be16 csum;
>>   
>>   		switch (type) {
>> +		case T10_PI_TYPE0_PROTECTION:
>> +			break;
>>   		case T10_PI_TYPE1_PROTECTION:
>>   		case T10_PI_TYPE2_PROTECTION:
>>   			if (pi->app_tag == T10_PI_APP_ESCAPE)
>> -- 
>> 2.20.0
> I didn't have the break in my local patch but I think this is more
> correct based on the description of the enums. Like Nick pointed out,
> there is no functional change because this value is not used in this
> file.
>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

Hi,

we had a thread with Martin regarding this issue and we decided to set a 
default clause and add a BUG() in case we get there.

I've sent a patch with this fix.

-Max.