USB: serial: ti_usb_3410_5052: Avoid goto in bulk in callback

[Johan Hovold <johan@kernel.org>]

On Mon, Dec 11, 2017 at 12:09:19AM +0100, Ladislav Michl wrote:
> Make status handling in bulk in callback function more compact,
> which renders goto pointless.
> 
> Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> ---
>  drivers/usb/serial/ti_usb_3410_5052.c | 36 ++++++++++++++---------------------
>  1 file changed, 14 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
> index 6b22857f6e52..2786ec7bbca2 100644
> --- a/drivers/usb/serial/ti_usb_3410_5052.c
> +++ b/drivers/usb/serial/ti_usb_3410_5052.c
> @@ -1219,29 +1219,10 @@ static void ti_bulk_in_callback(struct urb *urb)
>  
>  	switch (status) {
>  	case 0:
> -		break;
> -	case -ECONNRESET:
> -	case -ENOENT:
> -	case -ESHUTDOWN:
> -		dev_dbg(dev, "%s - urb shutting down, %d\n", __func__, status);
> -		return;
> -	default:
> -		dev_err(dev, "%s - nonzero urb status, %d\n",
> -			__func__, status);
> -	}
> -
> -	if (status == -EPIPE)
> -		goto exit;
> -
> -	if (status) {
> -		dev_err(dev, "%s - stopping read!\n", __func__);
> -		return;
> -	}
> -
> -	if (urb->actual_length) {
> +		if (!urb->actual_length)
> +			break;
>  		usb_serial_debug_data(dev, __func__, urb->actual_length,
>  				      urb->transfer_buffer);
> -
>  		if (!tport->tp_is_open)
>  			dev_dbg(dev, "%s - port closed, dropping data\n",
>  				__func__);
> @@ -1250,9 +1231,20 @@ static void ti_bulk_in_callback(struct urb *urb)
>  		spin_lock(&tport->tp_lock);
>  		port->icount.rx += urb->actual_length;
>  		spin_unlock(&tport->tp_lock);
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +		dev_dbg(dev, "%s - urb shutting down, %d\n", __func__, status);
> +		return;
> +	case -EPIPE:
> +		break;
> +	default:
> +		dev_err(dev, "%s - nonzero urb status, %d\n",
> +			__func__, status);
> +		return;

I'm afraid I don't consider this an improvement. I prefer using gotos
for error paths, while keeping the success path out of the status
switch.

Furthermore, this isn't functionally equivalent as we'd not longer log
an error for -EPIPE.

In fact, that -EPIPE is already on my TODO list as we really should not
be resubmitting URBs for a stalled endpoint in the first place. That in
turn should allow for some clean up of this callback.

Thanks,
Johan
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