Fix DMA rx ring buffer handling

Reported-by: Qian Zhang <zhangq@sansitech.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index d7b2716..12b11da 100644 (file)
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -401,9 +401,11 @@ static void bfin_serial_dma_rx_chars(struct bfin_serial_port *uart)
        else
                flg = TTY_NORMAL;
 
-       for (i = uart->rx_dma_buf.tail; i != uart->rx_dma_buf.head; i++) {
+       for (i = uart->rx_dma_buf.tail; ; i++) {
                if (i >= UART_XMIT_SIZE)
                        i = 0;
+               if (i == uart->rx_dma_buf.head)
+                       break;
                if (!uart_handle_sysrq_char(&uart->port, uart->rx_dma_buf.buf[i]))
                        uart_insert_char(&uart->port, status, OE,
                                uart->rx_dma_buf.buf[i], flg);