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alistair23-linux
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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>
hifive-unleashed-5.1
Peter Hurley 2014-10-16 15:33:26 -04:00 committed by Greg Kroah-Hartman
parent 6054c16e80
commit 54e8e5fcaa
2 changed files with 6 additions and 6 deletions
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4
drivers/tty/n_tty.c
View File

@ -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);
}
/**

8
drivers/tty/pty.c
View File

@ -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);
}
/**