linux-kernel - Re: [PATCH v3 3/3] serial: core: Update uart_poll_timeout() function to return unsigned long

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Message-ID: <2023102712-frolic-bush-3d67@gregkh>
Date:   Fri, 27 Oct 2023 08:43:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Vamshi Gajjela <vamshigajjela@...gle.com>
Cc:     Jiri Slaby <jirislaby@...nel.org>, ilpo.jarvinen@...ux.intel.com,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        manugautam@...gle.com, Subhash Jadavani <sjadavani@...gle.com>,
        Channa Kadabi <kadabi@...gle.com>
Subject: Re: [PATCH v3 3/3] serial: core: Update uart_poll_timeout() function
 to return unsigned long

On Thu, Oct 26, 2023 at 07:26:28PM +0530, Vamshi Gajjela wrote:
> From: VAMSHI GAJJELA <vamshigajjela@...gle.com>

Please use lower case letters like I think you mean to?

Also, where are patches 1/3 and 2/3 of this series?  I can't do anything
without them as well.

> The function uart_fifo_timeout() returns an unsigned long value, which
> is the number of jiffies. Therefore, change the variable timeout in the
> function uart_poll_timeout() from int to unsigned long.
> Change the return type of the function uart_poll_timeout() from int to
> unsigned long to be consistent with the type of timeout values.
> 
> Signed-off-by: VAMSHI GAJJELA <vamshigajjela@...gle.com>
> ---
> v3:
> - updated description
> v2:
> - unsigned long instead of unsigned int
> - added () after function name in short log
> - updated description
> 
>  include/linux/serial_core.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index bb6f073bc159..6916a1d7e477 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -773,9 +773,9 @@ static inline unsigned long uart_fifo_timeout(struct uart_port *port)
>  }
>  
>  /* Base timer interval for polling */
> -static inline int uart_poll_timeout(struct uart_port *port)
> +static inline unsigned long uart_poll_timeout(struct uart_port *port)
>  {
> -	int timeout = uart_fifo_timeout(port);
> +	unsigned long timeout = uart_fifo_timeout(port);
>  
>  	return timeout > 6 ? (timeout / 2 - 2) : 1;

So we are now doing 64bit math?  Did that just make things slower?

What bug is this actually fixing?  How have you tested this to verify it
works?

thanks,

greg k-h