Function sysctl_vmm_destroy

freebsd/amd64/vmm/vmm_dev.c:979–1039

}

static int
sysctl_vmm_destroy(SYSCTL_HANDLER_ARGS)
{
	struct devmem_softc *dsc;
	struct vmmdev_softc *sc;
	struct cdev *cdev;
	char *buf;
	int error, buflen;

	error = vmm_priv_check(req->td->td_ucred);
	if (error)
		return (error);

	buflen = VM_MAX_NAMELEN + 1;
	buf = malloc(buflen, M_VMMDEV, M_WAITOK | M_ZERO);
	strlcpy(buf, "beavis", buflen);
	error = sysctl_handle_string(oidp, buf, buflen, req);
	if (error != 0 || req->newptr == NULL)
		goto out;

	mtx_lock(&vmmdev_mtx);
	sc = vmmdev_lookup(buf);
	if (sc == NULL || sc->cdev == NULL) {
		mtx_unlock(&vmmdev_mtx);
		error = EINVAL;
		goto out;
	}

	/*
	 * The 'cdev' will be destroyed asynchronously when 'si_threadcount'
	 * goes down to 0 so we should not do it again in the callback.
	 *
	 * Setting 'sc->cdev' to NULL is also used to indicate that the VM
	 * is scheduled for destruction.
	 */
	cdev = sc->cdev;
	sc->cdev = NULL;		
	mtx_unlock(&vmmdev_mtx);

	/*
	 * Schedule all cdevs to be destroyed:
	 *
	 * - any new operations on the 'cdev' will return an error (ENXIO).
	 *
	 * - when the 'si_threadcount' dwindles down to zero the 'cdev' will
	 *   be destroyed and the callback will be invoked in a taskqueue
	 *   context.
	 *
	 * - the 'devmem' cdevs are destroyed before the virtual machine 'cdev'
	 */
	SLIST_FOREACH(dsc, &sc->devmem, link) {
		KASSERT(dsc->cdev != NULL, ("devmem cdev already destroyed"));
		destroy_dev_sched_cb(dsc->cdev, devmem_destroy, dsc);
	}
	destroy_dev_sched_cb(cdev, vmmdev_destroy, sc);
	error = 0;

out: