diff options
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 53e6db8b0330..bcfdaf6ddbb2 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -195,10 +195,15 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, if (!state->xmit.buf) { state->xmit.buf = (unsigned char *) page; uart_circ_clear(&state->xmit); + uart_port_unlock(uport, flags); } else { + uart_port_unlock(uport, flags); + /* + * Do not free() the page under the port lock, see + * uart_shutdown(). + */ free_page(page); } - uart_port_unlock(uport, flags); retval = uport->ops->startup(uport); if (retval == 0) { @@ -258,6 +263,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) struct uart_port *uport = uart_port_check(state); struct tty_port *port = &state->port; unsigned long flags = 0; + char *xmit_buf = NULL; /* * Set the TTY IO error marker @@ -288,14 +294,18 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) tty_port_set_suspended(port, 0); /* - * Free the transmit buffer page. + * Do not free() the transmit buffer page under the port lock since + * this can create various circular locking scenarios. For instance, + * console driver may need to allocate/free a debug object, which + * can endup in printk() recursion. */ uart_port_lock(state, flags); - if (state->xmit.buf) { - free_page((unsigned long)state->xmit.buf); - state->xmit.buf = NULL; - } + xmit_buf = state->xmit.buf; + state->xmit.buf = NULL; uart_port_unlock(uport, flags); + + if (xmit_buf) + free_page((unsigned long)xmit_buf); } /** |