8250: Fix tcsetattr to avoid ioctl(TIOCMIWAIT) hang

[karo-tx-linux.git] / drivers / serial / 8250.c

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 4d8e14b7aa931bcf3de11c6e5805005e0bf413ca..dd5e1ac22251a86692ed79162baca4e0f728a4c4 100644 (file)
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2343,8 +2343,11 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 
        /*
         * CTS flow control flag and modem status interrupts
+        * Only disable MSI if no threads are waiting in
+        * serial_core::uart_wait_modem_status
         */
-       up->ier &= ~UART_IER_MSI;
+       if (!waitqueue_active(&up->port.state->port.delta_msr_wait))
+               up->ier &= ~UART_IER_MSI;
        if (!(up->bugs & UART_BUG_NOMSR) &&
                        UART_ENABLE_MS(&up->port, termios->c_cflag))
                up->ier |= UART_IER_MSI;