Am Samstag, 18. Juli 2009 00:19:51 schrieb Matthew Garrett:
> I've finally got a bit further with this. The usb_submit_urb() call in
> usb_serial_generic_open fails because urb->hcpriv is set. Race between
> the resume call and the open occuring?
No, this looks like a big fat logic bug, not a race. The resume handler
has to resubmit the reading URBs if the device is resumed while opened.
But the open() method bumps the counter before it resumes a device.
The fix is to increment the counter only after the resumption or if no
resumption is attempted. Does this patch fix the problem?
Regards
Oliver
--
commit af2a33e9c9df3aec136d9ccaac4a803bed5c6020
Author: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Sat Jul 18 07:19:04 2009 +0200
usb: fix counter logic in opening serial converters
the usage counter must be increased only after autoresumption
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index bd7581b..c6f69c0 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -214,15 +214,13 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
goto bailout_port_put;
}
- ++port->port.count;
-
/* set up our port structure making the tty driver
* remember our port object, and us it */
tty->driver_data = port;
tty_port_tty_set(&port->port, tty);
/* If the console is attached, the device is already open */
- if (port->port.count == 1 && !port->console) {
+ if (!port->port.count && !port->console) {
/* lock this module before we call it
* this may fail, which means we must bail out,
@@ -240,12 +238,16 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
if (retval)
goto bailout_module_put;
+ ++port->port.count;
+
/* only call the device specific open if this
* is the first time the port is opened */
retval = serial->type->open(tty, port, filp);
if (retval)
goto bailout_interface_put;
mutex_unlock(&serial->disc_mutex);
+ } else {
+ ++port->port.count;
}
mutex_unlock(&port->mutex);
/* Now do the correct tty layer semantics */
--
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