Merge with /home/shaggy/git/linus-clean/

1 files changed, 189 insertions, 0 deletions

diff --git a/net/tipc/ref.c b/net/tipc/ref.c
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+/*
+ * net/tipc/ref.c: TIPC object registry code
+ * 
+ * Copyright (c) 1991-2006, Ericsson AB
+ * Copyright (c) 2004-2005, Wind River Systems
+ * 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.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
+ */
+
+#include "core.h"
+#include "ref.h"
+#include "port.h"
+#include "subscr.h"
+#include "name_distr.h"
+#include "name_table.h"
+#include "config.h"
+#include "discover.h"
+#include "bearer.h"
+#include "node.h"
+#include "bcast.h"
+
+/*
+ * Object reference table consists of 2**N entries.
+ *
+ * A used entry has object ptr != 0, reference == XXXX|own index
+ *				     (XXXX changes each time entry is acquired) 
+ * A free entry has object ptr == 0, reference == YYYY|next free index
+ *				     (YYYY is one more than last used XXXX)
+ *
+ * Free list is initially chained from entry (2**N)-1 to entry 1. 
+ * Entry 0 is not used to allow index 0 to indicate the end of the free list.
+ *
+ * Note: Any accidental reference of the form XXXX|0--0 won't match entry 0
+ * because entry 0's reference field has the form XXXX|1--1.
+ */
+
+struct ref_table tipc_ref_table = { 0 };
+
+static rwlock_t ref_table_lock = RW_LOCK_UNLOCKED;
+
+/**
+ * tipc_ref_table_init - create reference table for objects
+ */
+
+int tipc_ref_table_init(u32 requested_size, u32 start)
+{
+	struct reference *table;
+	u32 sz = 1 << 4;
+	u32 index_mask;
+	int i;
+
+	while (sz < requested_size) {
+		sz <<= 1;
+	}
+	table = (struct reference *)vmalloc(sz * sizeof(struct reference));
+	if (table == NULL)
+		return -ENOMEM;
+
+	write_lock_bh(&ref_table_lock);
+	index_mask = sz - 1;
+	for (i = sz - 1; i >= 0; i--) {
+		table[i].object = 0;
+		table[i].lock = SPIN_LOCK_UNLOCKED;
+		table[i].data.next_plus_upper = (start & ~index_mask) + i - 1;
+	}
+	tipc_ref_table.entries = table;
+	tipc_ref_table.index_mask = index_mask;
+	tipc_ref_table.first_free = sz - 1;
+	tipc_ref_table.last_free = 1;
+	write_unlock_bh(&ref_table_lock);
+	return TIPC_OK;
+}
+
+/**
+ * tipc_ref_table_stop - destroy reference table for objects
+ */
+
+void tipc_ref_table_stop(void)
+{
+	if (!tipc_ref_table.entries)
+		return;
+
+	vfree(tipc_ref_table.entries);
+	tipc_ref_table.entries = 0;
+}
+
+/**
+ * tipc_ref_acquire - create reference to an object
+ * 
+ * Return a unique reference value which can be translated back to the pointer
+ * 'object' at a later time.  Also, pass back a pointer to the lock protecting 
+ * the object, but without locking it.
+ */
+
+u32 tipc_ref_acquire(void *object, spinlock_t **lock)
+{
+	struct reference *entry;
+	u32 index;
+	u32 index_mask;
+	u32 next_plus_upper;
+	u32 reference = 0;
+
+	assert(tipc_ref_table.entries && object);
+
+	write_lock_bh(&ref_table_lock);
+	if (tipc_ref_table.first_free) {
+		index = tipc_ref_table.first_free;
+		entry = &(tipc_ref_table.entries[index]);
+		index_mask = tipc_ref_table.index_mask;
+		/* take lock in case a previous user of entry still holds it */ 
+		spin_lock_bh(&entry->lock);  
+		next_plus_upper = entry->data.next_plus_upper;
+		tipc_ref_table.first_free = next_plus_upper & index_mask;
+		reference = (next_plus_upper & ~index_mask) + index;
+		entry->data.reference = reference;
+		entry->object = object;
+                if (lock != 0)
+                        *lock = &entry->lock;
+		spin_unlock_bh(&entry->lock);
+	}
+	write_unlock_bh(&ref_table_lock);
+	return reference;
+}
+
+/**
+ * tipc_ref_discard - invalidate references to an object
+ * 
+ * Disallow future references to an object and free up the entry for re-use.
+ * Note: The entry's spin_lock may still be busy after discard
+ */
+
+void tipc_ref_discard(u32 ref)
+{
+	struct reference *entry;
+	u32 index; 
+	u32 index_mask;
+
+	assert(tipc_ref_table.entries);
+	assert(ref != 0);
+
+	write_lock_bh(&ref_table_lock);
+	index_mask = tipc_ref_table.index_mask;
+	index = ref & index_mask;
+	entry = &(tipc_ref_table.entries[index]);
+	assert(entry->object != 0);
+	assert(entry->data.reference == ref);
+
+	/* mark entry as unused */
+	entry->object = 0;
+	if (tipc_ref_table.first_free == 0)
+		tipc_ref_table.first_free = index;
+	else
+		/* next_plus_upper is always XXXX|0--0 for last free entry */
+		tipc_ref_table.entries[tipc_ref_table.last_free].data.next_plus_upper 
+			|= index;
+	tipc_ref_table.last_free = index;
+
+	/* increment upper bits of entry to invalidate subsequent references */
+	entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1);
+	write_unlock_bh(&ref_table_lock);
+}
+