linux-kernel - [PATCH 2/3] serial: 8250_omap: check how many bytes were injected

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Message-Id: <1439568064-7907-2-git-send-email-bigeasy@linutronix.de>
Date:	Fri, 14 Aug 2015 18:01:03 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	peter@...leysoftware.com
Cc:	linux-kernel@...r.kernel.org, nsekhar@...com,
	linux-omap@...r.kernel.org, linux-serial@...r.kernel.org,
	john.ogness@...utronix.de,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 2/3] serial: 8250_omap: check how many bytes were injected

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.

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);
 
-- 
2.5.0

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