usbd_ref_wait(9)

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.

SEE ALSO

usb(4), tsleep(9), wakeup(9)