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Date:   Tue, 6 Jun 2023 13:13:30 +0200
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Subject: Re: [PATCH v2 1/3] USB: serial: return errors from break handling
To:     Johan Hovold <johan@kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Corey Minyard <minyard@acm.org>
References: <20230604123505.4661-1-johan@kernel.org>
 <20230604123505.4661-2-johan@kernel.org>
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From:   Oliver Neukum <oneukum@suse.com>
In-Reply-To: <20230604123505.4661-2-johan@kernel.org>
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On 04.06.23 14:35, Johan Hovold wrote:
> @@ -1077,15 +1077,19 @@ static void pl2303_set_break(struct usb_serial_port *port, bool enable)
>   	result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
>   				 BREAK_REQUEST, BREAK_REQUEST_TYPE, state,
>   				 0, NULL, 0, 100);
> -	if (result)
> +	if (result) {
>   		dev_err(&port->dev, "error sending break = %d\n", result);
> +		return result;
> +	}
> +
> +	return 0;
>   }

Hi,

this code was always fishy, but I am afraid it worked by accident albeit
spamming the logs.
If I may quote from the kerneldoc of usb_control_msg():

  * usb_control_msg - Builds a control urb, sends it off and waits for completion

[..]

  * Return: If successful, the number of bytes transferred. Otherwise, a negative
  * error number.
  */

You need to test for < 0, not != 0

	Regards
		Oliver