Copyright 2014 Nexenta Systems, Inc. All rights reserved.
Copyright 2013, Joyent, Inc. All Rights Reserved.
Copyright (c) 2009, Sun Microsystems, Inc. All Rights Reserved
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License. You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
See the License for the specific language governing permissions and limitations under the License. When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with
the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
#include <sys/dditypes.h> #include <sys/sunddi.h> void ddi_periodic_delete(ddi_periodic_t request);
ddi_periodic_t opaque value returned by ddi_periodic_add(9F)
It is not possible to cancel a periodic invocation request from within the periodic callback itself; to do so is a programming error that will panic the system. Instead, requests must be cancelled from some other user or kernel context routine, such as the detach(9E) entry point of a module.
If the callback function is already executing (for instance, on another CPU) when the request is cancelled, ddi_periodic_delete() will block until it finishes executing and is completely unregistered. Because of this, locks acquired by the callback function must not be held across the call to ddi_periodic_delete() or a deadlock may result.
The callback will not be invoked again after the call to ddi_periodic_delete() returns.
In the following example, the device driver cancels the request by calling ddi_periodic_delete() and passing the opaque request identifier returned by a previous call to ddi_periodic_add(9F).
/*
* Stop the periodic timer.
*/
static void
stop_periodic_timer(struct my_state *statep)
{
ddi_periodic_delete(statep->periodic_id);
mutex_destroy(&statep->lock);
}
static void
start_periodic_timer(struct my_state *statep)
{
hrtime_t interval = CHECK_INTERVAL;
mutex_init(&statep->lock, NULL, MUTEX_DRIVER, DDI_IPL_0);
/*
* Register my_callback which is invoked periodically
* in CHECK_INTERVAL in kernel context.
*/
statep->periodic_id = ddi_periodic_add(my_periodic_func,
statep, interval, DDI_IPL_0);
}
static void
my_periodic_func(void *arg)
{
/*
* This handler is invoked periodically.
*/
struct my_state *statep = (struct my_state *)arg;
mutex_enter(&statep->lock);
if (load_unbalanced(statep)) {
balance_tasks(statep);
}
mutex_exit(&statep->lock);
}