Coherent4.2.10/include/kernel/ddi_lock.h

/* (-lgl
 *	Coherent 386 release 4.2
 *	Copyright (c) 1982, 1993 by Mark Williams Company.
 *	All rights reserved. May not be copied without permission.
 *	For copying permission and licensing info, write licensing@mwc.com
 -lgl) */

#ifndef	__KERNEL_DDI_LOCK_H__
#define	__KERNEL_DDI_LOCK_H__

/*
 * This is an internal header file, not intended for general use.
 *
 * This is a registry of value and constants for the lock hierarchy values
 * recommended for use in internal DDI/DKI basic and read/write locking
 * operations.  Many of these hierarchy values are outside the range that
 * are permitted to DDI/DKI-compliant drivers, and a special value in the
 * "lk_flags" member of the "lkinfop" structure passed to LOCK_ALLOC () is
 * necessary to permit access to this range of hierarchy values.
 *
 * We also specify a recommended minimum priority value here which should be
 * used with the indicated lock whenever a specific value is not indicated.
 */

#define	__LOCK_MIN(a,b)		((a) < (b) ? (a) : (b))


enum {
	INTERNAL_LOCK = 1,		/* access to reserved hierarchies */

	/*
	 * For the defer system.
	 */

	defer_hierarchy = 40,
#define	defer_priority		plhi


	/*
	 * Process-related locks.
	 */

	proc_global_hierarchy = 40,
#define	proc_global_priority	plhi

	/*
	 * For the kmem_... () pool.
	 */

	kmem_heap_hierarchy = 40,
#define	kmem_heap_priority	plhi


	/*
	 * The STREAMS schedule, bufcall event, qprocsoff (), and trace-
	 * sequence locks are all disjoint.
	 */

	stream_schedule_hierarchy = 40,
	stream_event_hierarchy = 40,
	stream_proc_hierarchy = 40,
	stream_seq_hierarchy = 40,


	/*
	 * For the timeout system. The timeout code calls defer_int_cpu (),
	 * so we have to be lower than defer.
	 */

	timeout_global_hierarchy = defer_hierarchy - 1,
#define	timeout_global_priority	plhi


	/*
	 * For streams, the stream directory lock nests outside the stream
	 * head lock, which nests outside STREAMS memory allocation. STREAMS
	 * locks are all at "plstr" by definition *except* for the streams
	 * heap locks, which have a priority conditional on various factors.
	 * Both of the streams heap locks call defer... () routines.
	 */

	stream_heap_hierarchy = kmem_heap_hierarchy - 1,

	/*
	 * For polling, the global lock nests outside the "pollhead" lock
	 * which nests outside the "pollwait" lock.  These must all be lower
	 * than the timeout lock code, since a timeout for a poll is taken out
	 * with the pollwait lock held.
	 */

	pollwait_hierarchy = timeout_global_hierarchy - 1,
#define	pollwait_priority 	plhi

	pollhead_hierarchy = pollwait_hierarchy - 1,
#define	pollhead_priority	plhi

	/*
	 * This has to nest outside the pollwait lock, since there are
	 * occasions when polling conditions are satisfied and pollwakeup()
	 * is called while a stream head is held locked.
	 */

	stream_head_hierarchy = __LOCK_MIN (stream_heap_hierarchy,
					    pollwait_hierarchy) - 1,

	/*
	 * The polling global lock must be lower than the stream head lock
	 * because we hold it around calls to the stream poll entry point to
	 * prevent race conditions.
	 */

	poll_global_hierarchy = __LOCK_MIN (pollhead_hierarchy,
					    stream_head_hierarchy) - 1,
#define	poll_global_priority	plhi


	/*
	 * This needs to be lower than the polling global lock because
	 * phfree () is called with this lock held when a stream is being
	 * deallocated.
	 */

	stream_dir_hierarchy = poll_global_hierarchy - 1
};

#endif	/* ! defined (__KERNEL_DDI_LOCK_H__) */