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authorPeter Hurley <peter@hurleysoftware.com>2014-10-16 15:33:26 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-05 16:34:36 -0800
commit54e8e5fcaae109f0303f52efb24f29bfac79ca86 (patch)
treed0d4e39526384367fa195b61a5aa2de686170a7d /drivers/tty/pty.c
parent6054c16e80318d32ee084a0f5620a863ae8cea33 (diff)
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>
Diffstat (limited to 'drivers/tty/pty.c')
-rw-r--r--drivers/tty/pty.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 29b5eeb01856..e554393d5551 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);
}
/**

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