pty: Don't claim slave's ctrl_lock for master's packet mode
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 <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index d521058..cd725cc 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -351,13 +351,13 @@
{
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);
}
/**