211 lines
6.2 KiB
C
211 lines
6.2 KiB
C
/*
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* net/tipc/ref.c: TIPC object registry code
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*
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* Copyright (c) 1991-2006, Ericsson AB
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* Copyright (c) 2004-2005, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "core.h"
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#include "ref.h"
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#include "port.h"
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#include "subscr.h"
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#include "name_distr.h"
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#include "name_table.h"
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#include "config.h"
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#include "discover.h"
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#include "bearer.h"
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#include "node.h"
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#include "bcast.h"
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/*
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* Object reference table consists of 2**N entries.
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*
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* A used entry has object ptr != 0, reference == XXXX|own index
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* (XXXX changes each time entry is acquired)
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* A free entry has object ptr == 0, reference == YYYY|next free index
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* (YYYY is one more than last used XXXX)
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*
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* Free list is initially chained from entry (2**N)-1 to entry 1.
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* Entry 0 is not used to allow index 0 to indicate the end of the free list.
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*
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* Note: Any accidental reference of the form XXXX|0--0 won't match entry 0
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* because entry 0's reference field has the form XXXX|1--1.
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*/
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struct ref_table tipc_ref_table = { NULL };
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static DEFINE_RWLOCK(ref_table_lock);
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/**
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* tipc_ref_table_init - create reference table for objects
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*/
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int tipc_ref_table_init(u32 requested_size, u32 start)
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{
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struct reference *table;
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u32 sz = 1 << 4;
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u32 index_mask;
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int i;
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while (sz < requested_size) {
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sz <<= 1;
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}
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table = vmalloc(sz * sizeof(*table));
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if (table == NULL)
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return -ENOMEM;
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write_lock_bh(&ref_table_lock);
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index_mask = sz - 1;
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for (i = sz - 1; i >= 0; i--) {
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table[i].object = NULL;
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spin_lock_init(&table[i].lock);
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table[i].data.next_plus_upper = (start & ~index_mask) + i - 1;
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}
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tipc_ref_table.entries = table;
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tipc_ref_table.index_mask = index_mask;
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tipc_ref_table.first_free = sz - 1;
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tipc_ref_table.last_free = 1;
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write_unlock_bh(&ref_table_lock);
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return TIPC_OK;
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}
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/**
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* tipc_ref_table_stop - destroy reference table for objects
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*/
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void tipc_ref_table_stop(void)
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{
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if (!tipc_ref_table.entries)
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return;
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vfree(tipc_ref_table.entries);
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tipc_ref_table.entries = NULL;
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}
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/**
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* tipc_ref_acquire - create reference to an object
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*
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* Return a unique reference value which can be translated back to the pointer
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* 'object' at a later time. Also, pass back a pointer to the lock protecting
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* the object, but without locking it.
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*/
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u32 tipc_ref_acquire(void *object, spinlock_t **lock)
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{
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struct reference *entry;
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u32 index;
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u32 index_mask;
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u32 next_plus_upper;
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u32 reference = 0;
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if (!object) {
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err("Attempt to acquire reference to non-existent object\n");
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return 0;
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}
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if (!tipc_ref_table.entries) {
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err("Reference table not found during acquisition attempt\n");
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return 0;
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}
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write_lock_bh(&ref_table_lock);
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if (tipc_ref_table.first_free) {
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index = tipc_ref_table.first_free;
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entry = &(tipc_ref_table.entries[index]);
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index_mask = tipc_ref_table.index_mask;
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/* take lock in case a previous user of entry still holds it */
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spin_lock_bh(&entry->lock);
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next_plus_upper = entry->data.next_plus_upper;
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tipc_ref_table.first_free = next_plus_upper & index_mask;
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reference = (next_plus_upper & ~index_mask) + index;
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entry->data.reference = reference;
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entry->object = object;
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if (lock != 0)
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*lock = &entry->lock;
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spin_unlock_bh(&entry->lock);
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}
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write_unlock_bh(&ref_table_lock);
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return reference;
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}
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/**
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* tipc_ref_discard - invalidate references to an object
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*
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* Disallow future references to an object and free up the entry for re-use.
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* Note: The entry's spin_lock may still be busy after discard
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*/
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void tipc_ref_discard(u32 ref)
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{
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struct reference *entry;
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u32 index;
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u32 index_mask;
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if (!ref) {
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err("Attempt to discard reference 0\n");
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return;
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}
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if (!tipc_ref_table.entries) {
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err("Reference table not found during discard attempt\n");
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return;
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}
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write_lock_bh(&ref_table_lock);
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index_mask = tipc_ref_table.index_mask;
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index = ref & index_mask;
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entry = &(tipc_ref_table.entries[index]);
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if (!entry->object) {
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err("Attempt to discard reference to non-existent object\n");
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goto exit;
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}
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if (entry->data.reference != ref) {
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err("Attempt to discard non-existent reference\n");
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goto exit;
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}
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/* mark entry as unused */
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entry->object = NULL;
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if (tipc_ref_table.first_free == 0)
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tipc_ref_table.first_free = index;
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else
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/* next_plus_upper is always XXXX|0--0 for last free entry */
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tipc_ref_table.entries[tipc_ref_table.last_free].data.next_plus_upper
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|= index;
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tipc_ref_table.last_free = index;
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/* increment upper bits of entry to invalidate subsequent references */
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entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1);
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exit:
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write_unlock_bh(&ref_table_lock);
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}
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