linux-kernel - [PATCH 1/6] serial: 8250: 8250_omap: Terminate DMA before pushing data on RX timeout

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Message-ID: <20200319110344.21348-2-vigneshr@ti.com>
Date:   Thu, 19 Mar 2020 16:33:39 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>
CC:     Vignesh Raghavendra <vigneshr@...com>,
        <linux-serial@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/6] serial: 8250: 8250_omap: Terminate DMA before pushing data on RX timeout

Terminate and flush DMA internal buffers, before pushing RX data to
higher layer. Otherwise, this will lead to data corruption, as driver
would end up pushing stale buffer data to higher layer while actual data
is still stuck inside DMA hardware and has yet not arrived at the
memory.
While at that, replace deprecated dmaengine_terminate_all() with
dmaengine_terminate_async().

Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
---
 drivers/tty/serial/8250/8250_omap.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index f04139923da0..65b6d165df67 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -755,7 +755,10 @@ static void __dma_rx_do_complete(struct uart_8250_port *p)
 	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
 
 	count = dma->rx_size - state.residue;
-
+	if (count < dma->rx_size)
+		dmaengine_terminate_async(dma->rxchan);
+	if (!count)
+		goto unlock;
 	ret = tty_insert_flip_string(tty_port, dma->rx_buf, count);
 
 	p->port.icount.rx += ret;
@@ -817,7 +820,6 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 	spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
 
 	__dma_rx_do_complete(p);
-	dmaengine_terminate_all(dma->rxchan);
 }
 
 static int omap_8250_rx_dma(struct uart_8250_port *p)
-- 
2.25.2