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| -rw-r--r-- | sys/vm/kern_lock.c | 377 |
1 files changed, 0 insertions, 377 deletions
diff --git a/sys/vm/kern_lock.c b/sys/vm/kern_lock.c deleted file mode 100644 index 2dce3b4..0000000 --- a/sys/vm/kern_lock.c +++ /dev/null @@ -1,377 +0,0 @@ -/* - * Copyright (c) 1991, 1993 - * The Regents of the University of California. All rights reserved. - * - * This code is derived from software contributed to Berkeley by - * The Mach Operating System project at Carnegie-Mellon University. - * - * 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. - * 3. All advertising materials mentioning features or use of this software - * must display the following acknowledgement: - * This product includes software developed by the University of - * California, Berkeley and its contributors. - * 4. Neither the name of the University nor the names of its contributors - * may be used to endorse or promote products derived from this software - * without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. - * - * from: @(#)kern_lock.c 8.1 (Berkeley) 6/11/93 - * - * - * Copyright (c) 1987, 1990 Carnegie-Mellon University. - * All rights reserved. - * - * Authors: Avadis Tevanian, Jr., Michael Wayne Young - * - * Permission to use, copy, modify and distribute this software and - * its documentation is hereby granted, provided that both the copyright - * notice and this permission notice appear in all copies of the - * software, derivative works or modified versions, and any portions - * thereof, and that both notices appear in supporting documentation. - * - * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" - * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND - * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. - * - * Carnegie Mellon requests users of this software to return to - * - * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU - * School of Computer Science - * Carnegie Mellon University - * Pittsburgh PA 15213-3890 - * - * any improvements or extensions that they make and grant Carnegie the - * rights to redistribute these changes. - * - * $Id$ - */ - -/* - * Locking primitives implementation - */ - -#include <sys/param.h> -#include <sys/systm.h> - -/* XXX */ -#include <sys/proc.h> - -#include <vm/vm.h> -#include <vm/vm_param.h> -#include <vm/vm_prot.h> -#include <vm/lock.h> - -/* - * Routine: lock_init - * Function: - * Initialize a lock; required before use. - * Note that clients declare the "struct lock" - * variables and then initialize them, rather - * than getting a new one from this module. - */ -void -lock_init(l, can_sleep) - lock_t l; - boolean_t can_sleep; -{ - l->want_write = 0; - l->want_upgrade = 0; - l->waiting = 0; - l->can_sleep = can_sleep; - l->read_count = 0; - l->proc = NULL; - l->recursion_depth = 0; -} - -void -lock_sleepable(l, can_sleep) - lock_t l; - boolean_t can_sleep; -{ - l->can_sleep = can_sleep; -} - - -/* - * Sleep locks. These use the same data structure and algorithm - * as the spin locks, but the process sleeps while it is waiting - * for the lock. These work on uniprocessor systems. - */ - -void -lock_write(l) - register lock_t l; -{ - if (l->proc == curproc) { - /* - * Recursive lock. - */ - l->recursion_depth++; - return; - } - /* - * Try to acquire the want_write bit. - */ - while (l->want_write) { - if (l->can_sleep && l->want_write) { - l->waiting = TRUE; - tsleep(l, PVM, "lckwt1", 0); - } - } - l->want_write = TRUE; - - /* Wait for readers (and upgrades) to finish */ - - while ((l->read_count != 0) || l->want_upgrade) { - if (l->can_sleep && (l->read_count != 0 || l->want_upgrade)) { - l->waiting = TRUE; - tsleep(l, PVM, "lckwt2", 0); - } - } -} - -void -lock_done(l) - register lock_t l; -{ - if (l->read_count != 0) - l->read_count--; - else if (l->recursion_depth != 0) - l->recursion_depth--; - else if (l->want_upgrade) - l->want_upgrade = FALSE; - else - l->want_write = FALSE; - - if (l->waiting) { - l->waiting = FALSE; - wakeup(l); - } -} - -void -lock_read(l) - register lock_t l; -{ - if (l->proc == curproc) { - /* - * Recursive lock. - */ - l->read_count++; - return; - } - while (l->want_write || l->want_upgrade) { - if (l->can_sleep && (l->want_write || l->want_upgrade)) { - l->waiting = TRUE; - tsleep(l, PVM, "lockrd", 0); - } - } - - l->read_count++; -} - -/* - * Routine: lock_read_to_write - * Function: - * Improves a read-only lock to one with - * write permission. If another reader has - * already requested an upgrade to a write lock, - * no lock is held upon return. - * - * Returns TRUE if the upgrade *failed*. - */ -boolean_t -lock_read_to_write(l) - register lock_t l; -{ - l->read_count--; - - if (l->proc == curproc) { - /* - * Recursive lock. - */ - l->recursion_depth++; - return (FALSE); - } - if (l->want_upgrade) { - /* - * Someone else has requested upgrade. Since we've released a - * read lock, wake him up. - */ - if (l->waiting) { - l->waiting = FALSE; - wakeup(l); - } - return (TRUE); - } - l->want_upgrade = TRUE; - - while (l->read_count != 0) { - if (l->can_sleep && l->read_count != 0) { - l->waiting = TRUE; - tsleep(l, PVM, "lckrw", 0); - } - } - - return (FALSE); -} - -void -lock_write_to_read(l) - register lock_t l; -{ - l->read_count++; - if (l->recursion_depth != 0) - l->recursion_depth--; - else if (l->want_upgrade) - l->want_upgrade = FALSE; - else - l->want_write = FALSE; - - if (l->waiting) { - l->waiting = FALSE; - wakeup(l); - } -} - - -/* - * Routine: lock_try_write - * Function: - * Tries to get a write lock. - * - * Returns FALSE if the lock is not held on return. - */ - -boolean_t -lock_try_write(l) - register lock_t l; -{ - if (l->proc == curproc) { - /* - * Recursive lock - */ - l->recursion_depth++; - return (TRUE); - } - if (l->want_write || l->want_upgrade || l->read_count) { - /* - * Can't get lock. - */ - return (FALSE); - } - /* - * Have lock. - */ - - l->want_write = TRUE; - return (TRUE); -} - -/* - * Routine: lock_try_read - * Function: - * Tries to get a read lock. - * - * Returns FALSE if the lock is not held on return. - */ - -boolean_t -lock_try_read(l) - register lock_t l; -{ - if (l->proc == curproc) { - /* - * Recursive lock - */ - l->read_count++; - return (TRUE); - } - if (l->want_write || l->want_upgrade) { - return (FALSE); - } - l->read_count++; - return (TRUE); -} - -/* - * Routine: lock_try_read_to_write - * Function: - * Improves a read-only lock to one with - * write permission. If another reader has - * already requested an upgrade to a write lock, - * the read lock is still held upon return. - * - * Returns FALSE if the upgrade *failed*. - */ -boolean_t -lock_try_read_to_write(l) - register lock_t l; -{ - if (l->proc == curproc) { - /* - * Recursive lock - */ - l->read_count--; - l->recursion_depth++; - return (TRUE); - } - if (l->want_upgrade) { - return (FALSE); - } - l->want_upgrade = TRUE; - l->read_count--; - - while (l->read_count != 0) { - l->waiting = TRUE; - tsleep(l, PVM, "lcktrw", 0); - } - - return (TRUE); -} - -/* - * Allow a process that has a lock for write to acquire it - * recursively (for read, write, or update). - */ -void -lock_set_recursive(l) - lock_t l; -{ - if (!l->want_write) { - panic("lock_set_recursive: don't have write lock"); - } - l->proc = curproc; -} - -/* - * Prevent a lock from being re-acquired. - */ -void -lock_clear_recursive(l) - lock_t l; -{ - if (l->proc != curproc) { - panic("lock_clear_recursive: wrong proc"); - } - if (l->recursion_depth == 0) - l->proc = NULL; -} |
