[PATCH] tty: serial: fsl_lpuart: make coverity happy

From: Michael Walle
Date: Fri Apr 03 2020 - 13:49:55 EST


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@xxxxxxxx>
Reported-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
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