#!/usr/sbin/dtrace -s
/*-
 * Copyright (c) 2015 Pawel Jakub Dawidek <pawel@dawidek.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: head/share/dtrace/blocking 288644 2015-10-04 00:40:12Z pjd $
 *
 * This little script is for use with programs that use event loop and should
 * sleep only when waiting for events (eg. via kevent(2)). When a program is
 * going to sleep in the kernel, the script will show its name, PID, kernel
 * stack trace and userland stack trace. Sleeping in kevent(2) is ignored.
 *
 * usage: blocking <execname>
 */

#pragma D option quiet

syscall::kevent:entry
/execname == $$1/
{
	self->inkevent = 1;
}

fbt::sleepq_add:entry
/!self->inkevent && execname == $$1/
{
	printf("\n%s(%d) is blocking...\n", execname, pid);
	stack();
	ustack();
}

syscall::kevent:return
/execname == $$1/
{
	self->inkevent = 0;
}