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Command: usbd_ref_wait | Section: 9 | Source: OpenBSD | File: usbd_ref_wait.9
USBD_REF_WAIT(9) FreeBSD Kernel Developer's Manual 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)
FreeBSD 14.1-RELEASE-p8 June 30, 2016 FreeBSD 14.1-RELEASE-p8