linux-kernel - [PATCH] tty: serial: fsl_lpuart: make coverity happy

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Date:   Fri,  3 Apr 2020 19:49:42 +0200
From:   Michael Walle <michael@...le.cc>
To:     linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Colin Ian King <colin.king@...onical.com>,
        NXP Linux Team <linux-imx@....com>,
        Michael Walle <michael@...le.cc>
Subject: [PATCH] tty: serial: fsl_lpuart: make coverity happy

Coverity reports the following:

  var_compare_op: Comparing chan to null implies that chan might be null.

  1234        if (chan)
  1235                dmaengine_terminate_all(chan);
  1236

  Dereference after null check (FORWARD_NULL)
  var_deref_op: Dereferencing null pointer chan.

  1237        dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);

Technically, this is correct. But lpuart_dma_rx_free() is guarded by
lpuart_dma_rx_use which is only true if there is a dma channel, see
lpuart_rx_dma_startup(). In any way, this looks bogus. So remove
the superfluous "if (chan)" check and make coverity happy.

Fixes: a092ab25fdaa ("tty: serial: fsl_lpuart: fix DMA mapping")
Signed-off-by: Michael Walle <michael@...le.cc>
Reported-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/tty/serial/fsl_lpuart.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 4cb04d8bf034..83d803729d23 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1210,9 +1210,7 @@ static void lpuart_dma_rx_free(struct uart_port *port)
 					struct lpuart_port, port);
 	struct dma_chan *chan = sport->dma_rx_chan;
 
-	if (chan)
-		dmaengine_terminate_all(chan);
-
+	dmaengine_terminate_all(chan);
 	dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
 	kfree(sport->rx_ring.buf);
 	sport->rx_ring.tail = 0;
-- 
2.20.1