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authorJohan Hovold <jhovold@gmail.com>2013-03-07 15:55:51 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-18 16:27:53 -0700
commit957dacaee56d18e5c2cbe722429de5a746a3cf44 (patch)
treed3043274b963ecf5c127bc6b77c94662ef056fd6
parente584a02cf517537a3d13c7f85ced45fd07ab85cd (diff)
downloadlinux-957dacaee56d18e5c2cbe722429de5a746a3cf44.tar.bz2
TTY: fix DTR not being dropped on hang up
Move HUPCL handling to port shutdown so that DTR is dropped also on hang up (tty_port_close is a noop for hung-up ports). Also do not try to drop DTR for uninitialised ports where it has never been raised (e.g. after a failed open). Note that this is also the current behaviour of serial-core. Nine drivers currently call tty_port_close_start directly (rather than through tty_port_close) and seven of them lower DTR as part of their close (if the port has been initialised). Fixup the remaining two drivers so that it continues to be lowered also on normal (non-HUP) close. [ Note that most of those other seven drivers did not expect DTR to have been dropped by tty_port_close_start in the first place. ] Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/mxser.c4
-rw-r--r--drivers/tty/n_gsm.c4
-rw-r--r--drivers/tty/tty_port.c27
3 files changed, 23 insertions, 12 deletions
diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 484b6a3c9b03..d996038eacfd 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -1084,6 +1084,10 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
mutex_lock(&port->mutex);
mxser_close_port(port);
mxser_flush_buffer(tty);
+ if (test_bit(ASYNCB_INITIALIZED, &port->flags)) {
+ if (C_HUPCL(tty))
+ tty_port_lower_dtr_rts(port);
+ }
mxser_shutdown_port(port);
clear_bit(ASYNCB_INITIALIZED, &port->flags);
mutex_unlock(&port->mutex);
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 74d9a0258d7c..642239015b46 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2964,6 +2964,10 @@ static void gsmtty_close(struct tty_struct *tty, struct file *filp)
if (tty_port_close_start(&dlci->port, tty, filp) == 0)
goto out;
gsm_dlci_begin_close(dlci);
+ if (test_bit(ASYNCB_INITIALIZED, &dlci->port.flags)) {
+ if (C_HUPCL(tty))
+ tty_port_lower_dtr_rts(&dlci->port);
+ }
tty_port_close_end(&dlci->port, tty);
tty_port_tty_set(&dlci->port, NULL);
out:
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 7e3eaf4eb9fe..0af8d9aa5b02 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -196,13 +196,20 @@ void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
}
EXPORT_SYMBOL(tty_port_tty_set);
-static void tty_port_shutdown(struct tty_port *port)
+static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
{
mutex_lock(&port->mutex);
if (port->console)
goto out;
if (test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags)) {
+ /*
+ * Drop DTR/RTS if HUPCL is set. This causes any attached
+ * modem to hang up the line.
+ */
+ if (tty && C_HUPCL(tty))
+ tty_port_lower_dtr_rts(port);
+
if (port->ops->shutdown)
port->ops->shutdown(port);
}
@@ -220,18 +227,19 @@ out:
void tty_port_hangup(struct tty_port *port)
{
+ struct tty_struct *tty;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
port->count = 0;
port->flags &= ~ASYNC_NORMAL_ACTIVE;
- if (port->tty) {
- set_bit(TTY_IO_ERROR, &port->tty->flags);
- tty_kref_put(port->tty);
- }
+ tty = port->tty;
+ if (tty)
+ set_bit(TTY_IO_ERROR, &tty->flags);
port->tty = NULL;
spin_unlock_irqrestore(&port->lock, flags);
- tty_port_shutdown(port);
+ tty_port_shutdown(port, tty);
+ tty_kref_put(tty);
wake_up_interruptible(&port->open_wait);
wake_up_interruptible(&port->delta_msr_wait);
}
@@ -485,11 +493,6 @@ int tty_port_close_start(struct tty_port *port,
/* Flush the ldisc buffering */
tty_ldisc_flush(tty);
- /* Drop DTR/RTS if HUPCL is set. This causes any attached modem to
- hang up the line */
- if (tty->termios.c_cflag & HUPCL)
- tty_port_lower_dtr_rts(port);
-
/* Don't call port->drop for the last reference. Callers will want
to drop the last active reference in ->shutdown() or the tty
shutdown path */
@@ -524,7 +527,7 @@ void tty_port_close(struct tty_port *port, struct tty_struct *tty,
{
if (tty_port_close_start(port, tty, filp) == 0)
return;
- tty_port_shutdown(port);
+ tty_port_shutdown(port, tty);
set_bit(TTY_IO_ERROR, &tty->flags);
tty_port_close_end(port, tty);
tty_port_tty_set(port, NULL);