[PATCH 03/18] Blackfin Serial Driver: fix a bug in dma circle rx buffer handling - v2

[sonic zhang <sonic.adi@gmail.com>]

The rx buffer tail index may increase to UART_XMIT_SIZE, which is not a valid
index, at the beginning of the Loop. The exit check should happen after this
index is adjusted properly.

Reported-by: Qian Zhang <zhangq@sansitech.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
---
 drivers/serial/bfin_5xx.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 350bfc4..1e027e3 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -402,9 +402,11 @@ 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);
-- 
1.6.0