linux-kernel - Re: [PATCH V3] tty: serial: fsl_lpuart: count tty buffer overruns

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Date:   Thu, 13 Jan 2022 08:23:41 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Sherry Sun <sherry.sun@....com>, gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-imx@....com
Subject: Re: [PATCH V3] tty: serial: fsl_lpuart: count tty buffer overruns

On 11. 01. 22, 9:51, Sherry Sun wrote:
> Added support for counting the tty buffer overruns in fsl_lpuart driver
> like other uart drivers.
> 
> Signed-off-by: Sherry Sun <sherry.sun@....com>

Reviewed-by: Jiri Slaby <jirislaby@...nel.org>

> ---
> changes in V3
> 
> 1. Remove the initialization for copied as it is not necessary.
> ---
>   drivers/tty/serial/fsl_lpuart.c | 20 +++++++++++++-------
>   1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index ce3e26144689..7d90c5a530ee 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -931,7 +931,8 @@ static void lpuart_rxint(struct lpuart_port *sport)
>   			sport->port.sysrq = 0;
>   		}
>   
> -		tty_insert_flip_char(port, rx, flg);
> +		if (tty_insert_flip_char(port, rx, flg) == 0)
> +			sport->port.icount.buf_overrun++;
>   	}
>   
>   out:
> @@ -1024,7 +1025,8 @@ static void lpuart32_rxint(struct lpuart_port *sport)
>   				flg = TTY_OVERRUN;
>   		}
>   
> -		tty_insert_flip_char(port, rx, flg);
> +		if (tty_insert_flip_char(port, rx, flg) == 0)
> +			sport->port.icount.buf_overrun++;
>   	}
>   
>   out:
> @@ -1116,7 +1118,7 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
>   	struct dma_chan *chan = sport->dma_rx_chan;
>   	struct circ_buf *ring = &sport->rx_ring;
>   	unsigned long flags;
> -	int count = 0;
> +	int count = 0, copied;
>   
>   	if (lpuart_is_32(sport)) {
>   		unsigned long sr = lpuart32_read(&sport->port, UARTSTAT);
> @@ -1218,20 +1220,24 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
>   	if (ring->head < ring->tail) {
>   		count = sport->rx_sgl.length - ring->tail;
>   
> -		tty_insert_flip_string(port, ring->buf + ring->tail, count);
> +		copied = tty_insert_flip_string(port, ring->buf + ring->tail, count);
> +		if (copied != count)
> +			sport->port.icount.buf_overrun++;
>   		ring->tail = 0;
> -		sport->port.icount.rx += count;
> +		sport->port.icount.rx += copied;
>   	}
>   
>   	/* Finally we read data from tail to head */
>   	if (ring->tail < ring->head) {
>   		count = ring->head - ring->tail;
> -		tty_insert_flip_string(port, ring->buf + ring->tail, count);
> +		copied = tty_insert_flip_string(port, ring->buf + ring->tail, count);
> +		if (copied != count)
> +			sport->port.icount.buf_overrun++;
>   		/* Wrap ring->head if needed */
>   		if (ring->head >= sport->rx_sgl.length)
>   			ring->head = 0;
>   		ring->tail = ring->head;
> -		sport->port.icount.rx += count;
> +		sport->port.icount.rx += copied;
>   	}
>   
>   exit:


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