Greg --
Here is a new version of the patch to usb-serial.c to fix
the unbalanced kref and module get/put in serial_open and
serial_close when there are errors. This version works
correctly when try_module_get fails and now "rmmod --wait"
works correctly.
This patch applies to 2.6.10-rc1-bk20.
Please apply.
Thanks,
-- Al
Change Log
* If the low level usb serial open fails, the kref and
module use counts are decremented once in open. Before,
they were mistakenly decremented again in close.
* If try_module_get fails, the module use count is not
changed. Before, the module use count was mistakenly
decremented. Now "rmmod --wait" works correctly.
* The tty->driver_data pointer is never set to NULL once
the port is open. Before there was a small window when
it was mistakenly set to NULL for an already open port.
Signed-off-by: Al Borchers <[EMAIL PROTECTED]>
--- linux-2.6.10-rc1-bk20.orig/drivers/usb/serial/usb-serial.c 2004-11-10
09:30:10.000000000 -0600
+++ linux-2.6.10-rc1-bk20.new/drivers/usb/serial/usb-serial.c 2004-11-11
01:33:52.000000000 -0600
@@ -480,45 +480,51 @@
struct usb_serial *serial;
struct usb_serial_port *port;
unsigned int portNumber;
- int retval = -ENODEV;
+ int retval;
dbg("%s", __FUNCTION__);
- /* initialize the pointer incase something fails */
- tty->driver_data = NULL;
-
/* get the serial object associated with this tty pointer */
serial = usb_serial_get_by_index(tty->index);
- if (!serial)
- goto bailout;
+ if (!serial) {
+ tty->driver_data = NULL;
+ return -ENODEV;
+ }
- /* set up our port structure making the tty driver remember our port
object, and us it */
portNumber = tty->index - serial->minor;
port = serial->port[portNumber];
- tty->driver_data = port;
-
- port->tty = tty;
- /* lock this module before we call it,
- this may, which means we must bail out, safe because we are called
with BKL held */
- if (!try_module_get(serial->type->owner)) {
- kref_put(&serial->kref, destroy_serial);
- goto bailout;
- }
-
- retval = 0;
++port->open_count;
+
if (port->open_count == 1) {
+
+ /* set up our port structure making the tty driver
+ * remember our port object, and us it */
+ tty->driver_data = port;
+ port->tty = tty;
+
+ /* lock this module before we call it
+ * this may fail, which means we must bail out,
+ * safe because we are called with BKL held */
+ if (!try_module_get(serial->type->owner)) {
+ retval = -ENODEV;
+ goto bailout_kref_put;
+ }
+
/* only call the device specific open if this
* is the first time the port is opened */
retval = serial->type->open(port, filp);
- if (retval) {
- port->open_count = 0;
- module_put(serial->type->owner);
- kref_put(&serial->kref, destroy_serial);
- }
+ if (retval)
+ goto bailout_module_put;
}
-bailout:
+
+ return 0;
+
+bailout_module_put:
+ module_put(serial->type->owner);
+bailout_kref_put:
+ kref_put(&serial->kref, destroy_serial);
+ port->open_count = 0;
return retval;
}
@@ -531,21 +537,24 @@
dbg("%s - port %d", __FUNCTION__, port->number);
+ if (port->open_count == 0)
+ return;
+
--port->open_count;
- if (port->open_count <= 0) {
+ if (port->open_count == 0) {
/* only call the device specific close if this
* port is being closed by the last owner */
port->serial->type->close(port, filp);
- port->open_count = 0;
if (port->tty) {
if (port->tty->driver_data)
port->tty->driver_data = NULL;
port->tty = NULL;
}
+
+ module_put(port->serial->type->owner);
}
- module_put(port->serial->type->owner);
kref_put(&port->serial->kref, destroy_serial);
}
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