This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / net / tipc / ref.h

diff --git a/net/tipc/ref.h b/net/tipc/ref.h
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+/*
+ * net/tipc/ref.h: Include file for TIPC object registry code
+ * 
+ * Copyright (c) 1991-2006, Ericsson AB
+ * Copyright (c) 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.
+ */
+
+#ifndef _TIPC_REF_H
+#define _TIPC_REF_H
+
+/**
+ * struct reference - TIPC object reference entry
+ * @object: pointer to object associated with reference entry
+ * @lock: spinlock controlling access to object
+ * @data: reference value associated with object (or link to next unused entry)
+ */
+ 
+struct reference {
+       void *object;
+       spinlock_t lock;
+       union {
+               u32 next_plus_upper;
+               u32 reference;
+       } data;
+};
+
+/**
+ * struct tipc_ref_table - table of TIPC object reference entries
+ * @entries: pointer to array of reference entries
+ * @index_mask: bitmask for array index portion of reference values
+ * @first_free: array index of first unused object reference entry
+ * @last_free: array index of last unused object reference entry
+ */
+
+struct ref_table {
+       struct reference *entries;
+       u32 index_mask;
+       u32 first_free;
+       u32 last_free;
+};
+
+extern struct ref_table tipc_ref_table;
+
+int tipc_ref_table_init(u32 requested_size, u32 start);
+void tipc_ref_table_stop(void);
+
+u32 tipc_ref_acquire(void *object, spinlock_t **lock);
+void tipc_ref_discard(u32 ref);
+
+
+/**
+ * tipc_ref_lock - lock referenced object and return pointer to it
+ */
+
+static inline void *tipc_ref_lock(u32 ref)
+{
+       if (likely(tipc_ref_table.entries)) {
+               struct reference *r =
+                       &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
+
+               spin_lock_bh(&r->lock);
+               if (likely(r->data.reference == ref))
+                       return r->object;
+               spin_unlock_bh(&r->lock);
+       }
+       return NULL;
+}
+
+/**
+ * tipc_ref_unlock - unlock referenced object 
+ */
+
+static inline void tipc_ref_unlock(u32 ref)
+{
+       if (likely(tipc_ref_table.entries)) {
+               struct reference *r =
+                       &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
+
+               if (likely(r->data.reference == ref))
+                       spin_unlock_bh(&r->lock);
+               else
+                       err("tipc_ref_unlock() invoked using obsolete reference\n");
+       }
+}
+
+/**
+ * tipc_ref_deref - return pointer referenced object (without locking it)
+ */
+
+static inline void *tipc_ref_deref(u32 ref)
+{
+       if (likely(tipc_ref_table.entries)) {
+               struct reference *r = 
+                       &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
+
+               if (likely(r->data.reference == ref))
+                       return r->object;
+       }
+       return NULL;
+}
+
+#endif