[PATCH] uart: mediatek: fix memory corruption issue

Zhiyong Tao
2021-07-10T09:05:20Z

This patch is used to fix memory corruption issue when rx power off.
1. add spin lock in mtk8250_dma_rx_complete function in APDMA mode.
2. add processing mechanism which count value is 0

Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com>
---
drivers/tty/serial/8250/8250_mtk.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index f7d3023f860f..09f7d2166315 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -91,12 +91,15 @@ static void mtk8250_dma_rx_complete(void *param)
struct mtk8250_data *data = up->port.private_data;
struct tty_port *tty_port = &up->port.state->port;
struct dma_tx_state state;
- int copied, total, cnt;
+ unsigned int copied, total, cnt;
unsigned char *ptr;
+ unsigned long flags;

if (data->rx_status == DMA_RX_SHUTDOWN)
return;

+ spin_lock_irqsave(&up->port.lock, flags);
+
dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
total = dma->rx_size - state.residue;
cnt = total;
@@ -104,9 +107,11 @@ static void mtk8250_dma_rx_complete(void *param)
if ((data->rx_pos + cnt) > dma->rx_size)
cnt = dma->rx_size - data->rx_pos;

- ptr = (unsigned char *)(data->rx_pos + dma->rx_buf);
- copied = tty_insert_flip_string(tty_port, ptr, cnt);
- data->rx_pos += cnt;
+ if (cnt != 0) {
+ ptr = (unsigned char *)(data->rx_pos + dma->rx_buf);
+ copied = tty_insert_flip_string(tty_port, ptr, cnt);
+ data->rx_pos += cnt;
+ }

if (total > cnt) {
ptr = (unsigned char *)(dma->rx_buf);
@@ -120,6 +125,8 @@ static void mtk8250_dma_rx_complete(void *param)
tty_flip_buffer_push(tty_port);

mtk8250_rx_dma(up);
+
+ spin_unlock_irqrestore(&up->port.lock, flags);
}

static void mtk8250_rx_dma(struct uart_8250_port *up)
--
2.18.0