From 4d90bb147ef6b91f529a21b498ff2b5fdc6785b4 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Wed, 10 Sep 2014 15:06:23 -0400 Subject: serial: core: Document and assert lock requirements for irq helpers The serial core provides two helper functions, uart_handle_dcd_change() and uart_handle_cts_change(), for UART drivers to use at interrupt time. The serial core expects the UART driver to hold the uart port lock when calling these helpers to prevent state corruption. If lockdep enabled, trigger a warning if the uart port lock is not held when calling these helper functions. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 5a78f69..f764de3 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2743,6 +2743,8 @@ EXPORT_SYMBOL(uart_match_port); * uart_handle_dcd_change - handle a change of carrier detect state * @uport: uart_port structure for the open port * @status: new carrier detect status, nonzero if active + * + * Caller must hold uport->lock */ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) { @@ -2750,6 +2752,8 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) struct tty_struct *tty = port->tty; struct tty_ldisc *ld; + lockdep_assert_held_once(&uport->lock); + if (tty) { ld = tty_ldisc_ref(tty); if (ld) { @@ -2774,12 +2778,16 @@ EXPORT_SYMBOL_GPL(uart_handle_dcd_change); * uart_handle_cts_change - handle a change of clear-to-send state * @uport: uart_port structure for the open port * @status: new clear to send status, nonzero if active + * + * Caller must hold uport->lock */ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) { struct tty_port *port = &uport->state->port; struct tty_struct *tty = port->tty; + lockdep_assert_held_once(&uport->lock); + uport->icount.cts++; if (tty_port_cts_enabled(port)) { -- cgit v1.1