linux-kernel - Re: [PATCH -next] usb: ftdi-elan: Fix if == else warnings in ftdi_elan_respond

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Date:   Wed, 23 Jan 2019 13:43:19 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     YueHaibing <yuehaibing@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH -next] usb: ftdi-elan: Fix if == else warnings in
 ftdi_elan_respond_engine

On Wed, Jan 23, 2019 at 08:34:42PM +0800, YueHaibing wrote:
> ./drivers/usb/misc/ftdi-elan.c:972:10-12: WARNING: possible condition with no effect (if == else)
> ./drivers/usb/misc/ftdi-elan.c:983:9-11: WARNING: possible condition with no effect (if == else)
> ./drivers/usb/misc/ftdi-elan.c:2052:11-13: WARNING: possible condition with no effect (if == else)
> 
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>

You can not just provide the output of a tool as a changelog text,
sorry.

Please explain what those lines mean, and why you are making the change
that you are.

> ---
>  drivers/usb/misc/ftdi-elan.c | 26 --------------------------
>  1 file changed, 26 deletions(-)
> 
> diff --git a/drivers/usb/misc/ftdi-elan.c b/drivers/usb/misc/ftdi-elan.c
> index 76c718a..257efac 100644
> --- a/drivers/usb/misc/ftdi-elan.c
> +++ b/drivers/usb/misc/ftdi-elan.c
> @@ -915,7 +915,6 @@ static int ftdi_elan_respond_engine(struct usb_ftdi *ftdi)
>  	int bytes_read = 0;
>  	int retry_on_empty = 1;
>  	int retry_on_timeout = 3;
> -	int empty_packets = 0;
>  read:{
>  		int packet_bytes = 0;
>  		int retval = usb_bulk_msg(ftdi->udev,
> @@ -960,31 +959,6 @@ read:{
>  			dev_err(&ftdi->udev->dev, "error = %d with packet_bytes = %d with total %d bytes%s\n",
>  				retval, packet_bytes, bytes_read, diag);
>  			return retval;
> -		} else if (packet_bytes == 2) {
> -			unsigned char s0 = ftdi->bulk_in_buffer[0];
> -			unsigned char s1 = ftdi->bulk_in_buffer[1];
> -			empty_packets += 1;
> -			if (s0 == 0x31 && s1 == 0x60) {
> -				if (retry_on_empty-- > 0) {
> -					goto more;
> -				} else
> -					return 0;
> -			} else if (s0 == 0x31 && s1 == 0x00) {
> -				if (retry_on_empty-- > 0) {
> -					goto more;
> -				} else
> -					return 0;
> -			} else {
> -				if (retry_on_empty-- > 0) {
> -					goto more;
> -				} else
> -					return 0;
> -			}
> -		} else if (packet_bytes == 1) {
> -			if (retry_on_empty-- > 0) {
> -				goto more;
> -			} else
> -				return 0;

Are you _sure_ that these lines are not needed and that the compiler is
not really seeing them?  As it doesn't look that way to me, what am I
missing?

thanks,

greg k-h