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252 lines
6.3 KiB
252 lines
6.3 KiB
/*
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* $Id$
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*
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* Copyright (C) 2001-2003 FhG Fokus
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*
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* This file is part of ser, a free SIP server.
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*
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* ser is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version
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*
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* For a license to use the ser software under conditions
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* other than those described here, or to purchase support for this
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* software, please contact iptel.org by e-mail at the following addresses:
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* info@iptel.org
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*
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* ser is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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* History:
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* --------
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* 2003-03-17 converted to locking.h (andrei)
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* 2004-07-28 s/lock_set_t/gen_lock_set_t/ because of a type conflict
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* on darwin (andrei)
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* 2006-03-07 removed timer_semaphore, timer_group_lock and related functions
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* since timers are now handled outside tm (andrei)
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*/
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#include "defs.h"
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#include <errno.h>
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#include "lock.h"
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#include "../../dprint.h"
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#ifndef GEN_LOCK_T_PREFERED
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/* semaphore probing limits */
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#define SEM_MIN 16
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#define SEM_MAX 4096
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/* we implement mutex here using lock sets; as the number of
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semaphores may be limited (e.g. sysv) and number of synchronized
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elements high, we partition the synced SER elements and share
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semaphores in each of the partitions; we try to use as many
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semaphores as OS gives us for finest granularity.
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we allocate the locks according to the following plans:
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1) we allocate a semaphore set for hash_entries and
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try to use as many semaphores in it as OS allows;
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we partition the hash_entries by available
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semaphores which are shared in each partition
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2) cells get always the same semaphore as its hash
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entry in which they live
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*/
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/* and the maximum number of semaphores in the entry_semaphore set */
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static int sem_nr;
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gen_lock_set_t* entry_semaphore=0;
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gen_lock_set_t* reply_semaphore=0;
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#endif
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/* initialize the locks; return 0 on success, -1 otherwise
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*/
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int lock_initialize()
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{
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#ifndef GEN_LOCK_T_PREFERED
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int i;
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int probe_run;
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#endif
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/* first try allocating semaphore sets with fixed number of semaphores */
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DBG("DEBUG: lock_initialize: lock initialization started\n");
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#ifndef GEN_LOCK_T_PREFERED
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i=SEM_MIN;
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/* probing phase: 0=initial, 1=after the first failure */
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probe_run=0;
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again:
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do {
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if (entry_semaphore!=0){ /* clean-up previous attempt */
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lock_set_destroy(entry_semaphore);
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lock_set_dealloc(entry_semaphore);
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}
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if (reply_semaphore!=0){
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lock_set_destroy(reply_semaphore);
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lock_set_dealloc(reply_semaphore);
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}
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if (i==0){
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LOG(L_CRIT, "lock_initialize: could not allocate semaphore"
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" sets\n");
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goto error;
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}
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if (((entry_semaphore=lock_set_alloc(i))==0)||
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(lock_set_init(entry_semaphore)==0)) {
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DBG("DEBUG: lock_initialize: entry semaphore "
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"initialization failure: %s\n", strerror( errno ) );
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if (entry_semaphore){
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lock_set_dealloc(entry_semaphore);
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entry_semaphore=0;
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}
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/* first time: step back and try again */
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if (probe_run==0) {
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DBG("DEBUG: lock_initialize: first time "
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"semaphore allocation failure\n");
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i--;
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probe_run=1;
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continue;
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/* failure after we stepped back; give up */
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} else {
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DBG("DEBUG: lock_initialize: second time semaphore"
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" allocation failure\n");
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goto error;
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}
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}
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/* allocation succeeded */
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if (probe_run==1) { /* if ok after we stepped back, we're done */
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break;
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} else { /* if ok otherwise, try again with larger set */
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if (i==SEM_MAX) break;
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else {
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i++;
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continue;
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}
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}
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} while(1);
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sem_nr=i;
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if (((reply_semaphore=lock_set_alloc(i))==0)||
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(lock_set_init(reply_semaphore)==0)){
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if (reply_semaphore){
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lock_set_dealloc(reply_semaphore);
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reply_semaphore=0;
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}
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DBG("DEBUG:lock_initialize: reply semaphore initialization"
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" failure: %s\n", strerror(errno));
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probe_run=1;
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i--;
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goto again;
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}
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/* return success */
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LOG(L_INFO, "INFO: semaphore arrays of size %d allocated\n", sem_nr );
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#endif /* GEN_LOCK_T_PREFERED*/
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return 0;
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#ifndef GEN_LOCK_T_PREFERED
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error:
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lock_cleanup();
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return -1;
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#endif
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}
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#ifdef GEN_LOCK_T_PREFERED
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void lock_cleanup()
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{
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/* must check if someone uses them, for now just leave them allocated*/
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}
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#else
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/* remove the semaphore set from system */
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void lock_cleanup()
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{
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/* that's system-wide; all other processes trying to use
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the semaphore will fail! call only if it is for sure
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no other process lives
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*/
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/* sibling double-check missing here; install a signal handler */
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if (entry_semaphore !=0){
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lock_set_destroy(entry_semaphore);
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lock_set_dealloc(entry_semaphore);
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};
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if (reply_semaphore !=0) {
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lock_set_destroy(reply_semaphore);
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lock_set_dealloc(reply_semaphore);
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};
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entry_semaphore = reply_semaphore = 0;
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}
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#endif /*GEN_LOCK_T_PREFERED*/
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int init_cell_lock( struct cell *cell )
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{
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#ifdef GEN_LOCK_T_PREFERED
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lock_init(&cell->reply_mutex);
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#else
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cell->reply_mutex.semaphore_set=reply_semaphore;
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cell->reply_mutex.semaphore_index = cell->hash_index % sem_nr;
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#endif /* GEN_LOCK_T_PREFERED */
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return 0;
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}
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int init_entry_lock( struct s_table* ht, struct entry *entry )
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{
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#ifdef GEN_LOCK_T_PREFERED
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lock_init(&entry->mutex);
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#else
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/* just advice which of the available semaphores to use;
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specifically, all entries are partitioned into as
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many partitions as number of available semaphores allows
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*/
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entry->mutex.semaphore_set=entry_semaphore;
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entry->mutex.semaphore_index = ( ((char *)entry - (char *)(ht->entries ) )
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/ sizeof(struct entry) ) % sem_nr;
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#endif
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return 0;
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}
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int release_cell_lock( struct cell *cell )
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{
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#ifndef GEN_LOCK_T_PREFERED
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/* don't do anything here -- the init_*_lock procedures
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just advised on usage of shared semaphores but did not
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generate them
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*/
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#endif
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return 0;
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}
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int release_entry_lock( struct entry *entry )
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{
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/* the same as above */
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return 0;
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}
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