freebsd-dev/lib/libkse/sys/lock.h
Daniel Eischen fd626336fd Add a method of yielding the current thread with the scheduler
lock held (_thr_sched_switch_unlocked()) and use this to avoid
dropping the scheduler lock and having the scheduler retake the
same lock again.

Add a better way of detecting if a low-level lock is in use.

When switching out a thread due to blocking in the UTS, don't
switch to the KSE's scheduler stack only to switch back to
another thread.  If possible switch to the new thread directly
from the old thread and avoid the overhead of the extra
context switch.

Check for pending signals on a thread when entering the scheduler
and add them to the threads signal frame.  This includes some
other minor signal fixes.

Most of this was a joint effor between davidxu and myself.

Reviewed by:	davidxu
Approved by:	re@ (blanket for libpthread)
2003-05-16 19:58:30 +00:00

94 lines
3.6 KiB
C

/*
* Copyright (c) 2001, 2003 Daniel Eischen <deischen@freebsd.org>.
* 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 AUTHOR 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.
*
* $FreeBSD$
*/
#ifndef _LOCK_H_
#define _LOCK_H_
struct lockreq;
struct lockuser;
struct lock;
enum lock_type {
LCK_DEFAULT = 0x0000, /* default is FIFO spin locks */
LCK_PRIORITY = 0x0001,
LCK_ADAPTIVE = 0x0002 /* call user-supplied handlers */
};
typedef void lock_handler_t(struct lock *, struct lockuser *);
struct lock {
struct lockreq *l_head;
struct lockreq *l_tail; /* only used for priority locks */
enum lock_type l_type;
lock_handler_t *l_wait; /* only used for adaptive locks */
lock_handler_t *l_wakeup; /* only used for adaptive locks */
};
/* Try to make this >= CACHELINESIZE */
struct lockreq {
volatile long lr_locked; /* lock granted = 0, busy otherwise */
struct lockuser *lr_watcher; /* only used for priority locks */
struct lockuser *lr_owner; /* only used for priority locks */
long lr_waiting; /* non-zero when wakeup needed */
volatile int lr_active; /* non-zero if the lock is last lock for thread */
};
struct lockuser {
struct lockreq *lu_myreq; /* request to give up/trade */
struct lockreq *lu_watchreq; /* watch this request */
int lu_priority; /* only used for priority locks */
void *lu_private1; /* private{1,2} are initialized to */
void *lu_private2; /* NULL and can be used by caller */
#define lu_private lu_private1
};
#define _LCK_INITIALIZER(lck_req) { &lck_req, NULL, LCK_DEFAULT, \
NULL, NULL }
#define _LCK_REQUEST_INITIALIZER { 0, NULL, NULL, 0 }
#define _LCK_BUSY(lu) ((lu)->lu_watchreq->lr_locked != 0)
#define _LCK_ACTIVE(lu) ((lu)->lu_watchreq->lr_active != 0)
#define _LCK_GRANTED(lu) ((lu)->lu_watchreq->lr_locked == 0)
#define _LCK_SET_PRIVATE(lu, p) (lu)->lu_private = (void *)(p)
#define _LCK_GET_PRIVATE(lu) (lu)->lu_private
#define _LCK_SET_PRIVATE2(lu, p) (lu)->lu_private2 = (void *)(p)
#define _LCK_GET_PRIVATE2(lu) (lu)->lu_private2
void _lock_destroy(struct lock *);
int _lock_init(struct lock *, enum lock_type,
lock_handler_t *, lock_handler_t *);
int _lockuser_init(struct lockuser *lu, void *priv);
void _lockuser_destroy(struct lockuser *lu);
void _lockuser_setactive(struct lockuser *lu, int active);
void _lock_acquire(struct lock *, struct lockuser *, int);
void _lock_release(struct lock *, struct lockuser *);
void _lock_grant(struct lock *, struct lockuser *);
#endif