NAME
usbd_ref_incr,
usbd_ref_decr, usbd_ref_wait
— wait for all USB device
references to complete
SYNOPSIS
#include
<dev/usb/usb.h>
#include <dev/usb/usbdi.h>
void
usbd_ref_incr(struct
usbd_device *dev);
void
usbd_ref_decr(struct
usbd_device *dev);
void
usbd_ref_wait(struct
usbd_device *dev);
DESCRIPTION
The
usbd_ref_wait()
function is used on a device level to tsleep(9) until the reference counter has reached zero.
To increase the reference counter use
usbd_ref_incr().
To decrease the reference counter use
usbd_ref_decr().
Once the reference counter has been decreased to zero,
usbd_ref_decr() will call
wakeup()
to interrupt the
tsleep()
at the point where usbd_ref_wait() was previously
set.
Typical use cases to wait for tasks to complete is at device closing or detachment.
CONTEXT
usbd_ref_incr(),
usbd_ref_decr(), and
usbd_ref_wait() can be called during autoconf or
from process context.