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>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index d7b271656a2d..12b11da40b49 100644
--- 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);