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

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Date:   Fri, 12 Oct 2018 10:04:02 +0100
From:   Ian Abbott <abbotti@....co.uk>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        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 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!

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

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