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path: root/drivers/usb
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Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/serial/usb-serial.c36
1 files changed, 31 insertions, 5 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index bd7581b3a48..99188c92068 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -32,6 +32,7 @@
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/uaccess.h>
+#include <linux/serial.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include "pl2303.h"
@@ -184,6 +185,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
struct usb_serial_port *port;
unsigned int portNumber;
int retval = 0;
+ int first = 0;
dbg("%s", __func__);
@@ -223,7 +225,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
/* If the console is attached, the device is already open */
if (port->port.count == 1 && !port->console) {
-
+ first = 1;
/* lock this module before we call it
* this may fail, which means we must bail out,
* safe because we are called with BKL held */
@@ -246,13 +248,21 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
if (retval)
goto bailout_interface_put;
mutex_unlock(&serial->disc_mutex);
+ set_bit(ASYNCB_INITIALIZED, &port->port.flags);
}
mutex_unlock(&port->mutex);
/* Now do the correct tty layer semantics */
retval = tty_port_block_til_ready(&port->port, tty, filp);
- if (retval == 0)
+ if (retval == 0) {
+ if (!first)
+ usb_serial_put(serial);
return 0;
-
+ }
+ mutex_lock(&port->mutex);
+ if (first == 0)
+ goto bailout_mutex_unlock;
+ /* Undo the initial port actions */
+ mutex_lock(&serial->disc_mutex);
bailout_interface_put:
usb_autopm_put_interface(serial->interface);
bailout_module_put:
@@ -340,6 +350,22 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
dbg("%s - port %d", __func__, port->number);
+ /* FIXME:
+ This leaves a very narrow race. Really we should do the
+ serial_do_free() on tty->shutdown(), but tty->shutdown can
+ be called from IRQ context and serial_do_free can sleep.
+
+ The right fix is probably to make the tty free (which is rare)
+ and thus tty->shutdown() occur via a work queue and simplify all
+ the drivers that use it.
+ */
+ if (tty_hung_up_p(filp)) {
+ /* serial_hangup already called serial_down at this point.
+ Another user may have already reopened the port but
+ serial_do_free is refcounted */
+ serial_do_free(port);
+ return;
+ }
if (tty_port_close_start(&port->port, tty, filp) == 0)
return;
@@ -355,7 +381,8 @@ static void serial_hangup(struct tty_struct *tty)
struct usb_serial_port *port = tty->driver_data;
serial_do_down(port);
tty_port_hangup(&port->port);
- serial_do_free(port);
+ /* We must not free port yet - the USB serial layer depends on it's
+ continued existence */
}
static int serial_write(struct tty_struct *tty, const unsigned char *buf,
@@ -394,7 +421,6 @@ static int serial_chars_in_buffer(struct tty_struct *tty)
struct usb_serial_port *port = tty->driver_data;
dbg("%s = port %d", __func__, port->number);
- WARN_ON(!port->port.count);
/* if the device was unplugged then any remaining characters
fell out of the connector ;) */
if (port->serial->disconnected)