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Message-ID: <55DDB4C7.5070709@hurleysoftware.com>
Date: Wed, 26 Aug 2015 08:44:55 -0400
From: Peter Hurley <peter@...leysoftware.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-kernel@...r.kernel.org, nsekhar@...com,
linux-omap@...r.kernel.org, linux-serial@...r.kernel.org,
john.ogness@...utronix.de,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 2/3] serial: 8250_omap: check how many bytes were injected
On 08/14/2015 12:01 PM, Sebastian Andrzej Siewior wrote:
> The function tty_insert_flip_string() returns an int and as such it
> might fail. So the result is that I kindly asked to insert 48 bytes and
> the function only insterted 32.
> I have no idea what to do with the remaining 16 so I think dropping them
> is the only option. I also increase the buf_overrun counter so userpace
> has a clue that we lost bytes.
No objection to the patch but I'm curious whether this is something you've
actually observed and under what circumstances.
Regards,
Peter Hurley
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
> drivers/tty/serial/8250/8250_omap.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
> index 2ac63c8bd946..933f7ef2c004 100644
> --- a/drivers/tty/serial/8250/8250_omap.c
> +++ b/drivers/tty/serial/8250/8250_omap.c
> @@ -738,6 +738,7 @@ static void __dma_rx_do_complete(struct uart_8250_port *p, bool error)
> struct dma_tx_state state;
> int count;
> unsigned long flags;
> + int ret;
>
> dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
> dma->rx_size, DMA_FROM_DEVICE);
> @@ -753,8 +754,10 @@ static void __dma_rx_do_complete(struct uart_8250_port *p, bool error)
>
> count = dma->rx_size - state.residue;
>
> - tty_insert_flip_string(tty_port, dma->rx_buf, count);
> - p->port.icount.rx += count;
> + ret = tty_insert_flip_string(tty_port, dma->rx_buf, count);
> +
> + p->port.icount.rx += ret;
> + p->port.icount.buf_overrun += count - ret;
> unlock:
> spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
>
>
--
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