From bafb0bd24d7e0e0124318625b239a55d58c757a2 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 25 Aug 2011 15:12:05 +0200 Subject: [PATCH] TTY: serial, move locking in uart_close So now, when we handle CLOSING flag, there is no point to hold port->mutex over the start of uart_close. Yes, there are still several things to reason about: * port->count etc is and always was protected by a spinlock * ->stop_rx is protected by a spinlock. Otherwise it would race with interrupts. * uart_wait_until_sent -- that one is already called without port->mutex from set_termios and tty_set_ldisc. Should anything be protected there, it would be tx_empty. And by a spinlock. 8250 does this internally... This step is needed to fix system stalls. To not create an AB-BA lock dependency (see next patches). Signed-off-by: Jiri Slaby Acked-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 849bd0d06b2c..0464360781fe 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1253,7 +1253,6 @@ static void uart_close(struct tty_struct *tty, struct file *filp) pr_debug("uart_close(%d) called\n", uport->line); - mutex_lock(&port->mutex); spin_lock_irqsave(&port->lock, flags); if (tty_hung_up_p(filp)) { @@ -1312,6 +1311,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp) uart_wait_until_sent(tty, uport->timeout); } + mutex_lock(&port->mutex); uart_shutdown(tty, state); uart_flush_buffer(tty); -- 2.39.5