Am Donnerstag, 24. September 2009 23:32:39 schrieb Johan Hovold:
> > You can, if you wish to hide what's going on, poison the urb. The
> > correct sequence is:
> >
> > 1. poison the urb
> > 2. cancel_delayed_work_sync
> >
> > 3. unpoison the urb
>
> <snip>
>
> > Step 1 sets a flag.
>
> And this is what we generally want to be doing I assume, rather than
> adding an explicit state flag?
If we do this we might just as well do it generically.
Alan, this uses flush_scheduled_work() prone to deadlocks.
I think I used it safely in this patch. Could you check?
Regards
Oliver
--
commit c9a1991c01c7a2650f124cab5c0549743c1e6da4
Author: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Mon Sep 28 13:11:10 2009 +0200
usb:usbserial: safe generic unlinking of all URBs
use usb_poison_urb() and flush_scheduled_work() for
a safe generic unlink of all URBs even if completion
handlers submit other URBs or drivers submit URBs
from work queues
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index aa6b2ae..2797956 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -311,6 +311,7 @@ static void serial_down(struct usb_serial_port *port)
if (drv->close)
drv->close(port);
mutex_unlock(&port->mutex);
+ kill_traffic();
}
static void serial_hangup(struct tty_struct *tty)
@@ -590,21 +591,17 @@ static void usb_serial_port_work(struct work_struct *work)
static void kill_traffic(struct usb_serial_port *port)
{
- usb_kill_urb(port->read_urb);
- usb_kill_urb(port->write_urb);
- /*
- * This is tricky.
- * Some drivers submit the read_urb in the
- * handler for the write_urb or vice versa
- * this order determines the order in which
- * usb_kill_urb() must be used to reliably
- * kill the URBs. As it is unknown here,
- * both orders must be used in turn.
- * The call below is not redundant.
- */
- usb_kill_urb(port->read_urb);
- usb_kill_urb(port->interrupt_in_urb);
- usb_kill_urb(port->interrupt_out_urb);
+ usb_poison_urb(port->read_urb);
+ usb_poison_urb(port->write_urb);
+ usb_poison_urb(port->interrupt_in_urb);
+ usb_poison_urb(port->interrupt_out_urb);
+
+ flush_scheduled_work();
+
+ usb_unpoison_urb(port->read_urb);
+ usb_unpoison_urb(port->write_urb);
+ usb_unpoison_urb(port->interrupt_in_urb);
+ usb_unpoison_urb(port->interrupt_out_urb);
}
static void port_release(struct device *dev)
--
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