The slave's ctrl_lock serializes updates to the ctrl_status field only, whereas the master's ctrl_lock serializes updates to the packet mode enable (ie., the master does not have ctrl_status and the slave does not have packet mode). Thus, claiming the slave's ctrl_lock to access ->packet is useless.
Unlocked reads of ->packet are already smp-safe. Signed-off-by: Peter Hurley <[email protected]> --- drivers/tty/n_tty.c | 4 ++-- drivers/tty/pty.c | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 53cdfbe..6a42204 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -351,13 +351,13 @@ static void n_tty_packet_mode_flush(struct tty_struct *tty) { unsigned long flags; - spin_lock_irqsave(&tty->ctrl_lock, flags); if (tty->link->packet) { + spin_lock_irqsave(&tty->ctrl_lock, flags); tty->ctrl_status |= TIOCPKT_FLUSHREAD; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); if (waitqueue_active(&tty->link->read_wait)) wake_up_interruptible(&tty->link->read_wait); } - spin_unlock_irqrestore(&tty->ctrl_lock, flags); } /** diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 29b5eeb..e554393 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -339,26 +339,26 @@ static void pty_start(struct tty_struct *tty) { unsigned long flags; - spin_lock_irqsave(&tty->ctrl_lock, flags); if (tty->link && tty->link->packet) { + spin_lock_irqsave(&tty->ctrl_lock, flags); tty->ctrl_status &= ~TIOCPKT_STOP; tty->ctrl_status |= TIOCPKT_START; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); } - spin_unlock_irqrestore(&tty->ctrl_lock, flags); } static void pty_stop(struct tty_struct *tty) { unsigned long flags; - spin_lock_irqsave(&tty->ctrl_lock, flags); if (tty->link && tty->link->packet) { + spin_lock_irqsave(&tty->ctrl_lock, flags); tty->ctrl_status &= ~TIOCPKT_START; tty->ctrl_status |= TIOCPKT_STOP; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); } - spin_unlock_irqrestore(&tty->ctrl_lock, flags); } /** -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
