When max_count is reached, the rx loop exits. However, UART_LSR has
already been read so those char flags are lost, and subsequent rx
status will be for the wrong byte until the rx fifo drains.
Reported-by: George Spelvin <linux@xxxxxxxxxxx>
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 7580d71..4868056 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1478,16 +1478,17 @@ static void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
* value, and returns the remaining LSR bits not handled
* by this Rx routine.
*/
-unsigned char
-serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
+unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
{
struct uart_port *port = &up->port;
int max_count = 256;
do {
serial8250_read_char(up, lsr);
+ if (--max_count == 0)
+ break;
lsr = serial_in(up, UART_LSR);
- } while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (--max_count > 0));
+ } while (lsr & (UART_LSR_DR | UART_LSR_BI));
spin_unlock(&port->lock);
tty_flip_buffer_push(&port->state->port);
spin_lock(&port->lock);
--
2.7.0
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