linux-kernel - Re: [PATCH] staging: comedi: tio: fix multiple missing break in switch bugs

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Message-ID: <d538f159-bc37-d4e9-3555-144232e361b1@embeddedor.com>
Date:   Fri, 12 Oct 2018 11:06:41 +0200
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Ian Abbott <abbotti@....co.uk>,
        H Hartley Sweeten <hsweeten@...ionengravers.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Spencer E. Olson" <olsonse@...ch.edu>
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: comedi: tio: fix multiple missing break in
 switch bugs



On 10/12/18 11:04 AM, Ian Abbott wrote:
> On 11/10/2018 20:05, Gustavo A. R. Silva wrote:
>> Currently, there are multiple missing break statements in two switch code
>> blocks. This makes the execution path to fall all the way down through
>> to the default cases, which makes the function ni_tio_set_gate_src() to
>> always return -EINVAL.
>>
>> Fix this by adding the missing break statements.
>>
>> Also, notice that due to the absence of the break statements,
>> the following pieces of code are unreachable:
>>
>> 1078    if (ret)
>> 1079            return ret;
>> 1080    /* 3.  reenable & set mode to starts things back up */
>> 1081    ni_tio_set_gate_mode(counter, src);
>>
>> 1098    if (ret)
>> 1099            return ret;
>> 1100    /* 3.  reenable & set mode to starts things back up */
>> 1101    ni_tio_set_gate2_mode(counter, src);
>>
>> So, by adding the missing breaks, this patch also fixes the problem
>> above.
>>
>> Addresses-Coverity-ID: 1474165 ("Missing break in switch")
>> Addresses-Coverity-ID: 1474162 ("Structurally dead code")
>> Fixes: 347e244884c3 ("staging: comedi: tio: implement global tio/ctr routing")
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>> ---
>>   drivers/staging/comedi/drivers/ni_tio.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/staging/comedi/drivers/ni_tio.c b/drivers/staging/comedi/drivers/ni_tio.c
>> index 838614e..0eb388c 100644
>> --- a/drivers/staging/comedi/drivers/ni_tio.c
>> +++ b/drivers/staging/comedi/drivers/ni_tio.c
>> @@ -1070,8 +1070,10 @@ int ni_tio_set_gate_src(struct ni_gpct *counter,
>>           case ni_gpct_variant_e_series:
>>           case ni_gpct_variant_m_series:
>>               ret = ni_m_set_gate(counter, chan);
>> +            break;
>>           case ni_gpct_variant_660x:
>>               ret = ni_660x_set_gate(counter, chan);
>> +            break;
>>           default:
>>               return -EINVAL;
>>           }
>> @@ -1090,8 +1092,10 @@ int ni_tio_set_gate_src(struct ni_gpct *counter,
>>           switch (counter_dev->variant) {
>>           case ni_gpct_variant_m_series:
>>               ret = ni_m_set_gate2(counter, chan);
>> +            break;
>>           case ni_gpct_variant_660x:
>>               ret = ni_660x_set_gate2(counter, chan);
>> +            break;
>>           default:
>>               return -EINVAL;
>>           }
>>
> 
> Thanks for catching that bug!
> 

Glad to help. :)

> Reviewed-by: Ian Abbott <abbotti@....co.uk>
> 

Thanks
--
Gustavo