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Diffstat (limited to 'net/tipc/ref.h')
| -rw-r--r-- | net/tipc/ref.h | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/net/tipc/ref.h b/net/tipc/ref.h new file mode 100644 index 00000000000..429cde57228 --- /dev/null +++ b/net/tipc/ref.h @@ -0,0 +1,131 @@ +/* + * 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 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 ref_table; + +int ref_table_init(u32 requested_size, u32 start); +void ref_table_stop(void); + +u32 ref_acquire(void *object, spinlock_t **lock); +void ref_discard(u32 ref); + + +/** + * ref_lock - lock referenced object and return pointer to it + */ + +static inline void *ref_lock(u32 ref) +{ + if (likely(ref_table.entries)) { + struct reference *r = + &ref_table.entries[ref & ref_table.index_mask]; + + spin_lock_bh(&r->lock); + if (likely(r->data.reference == ref)) + return r->object; + spin_unlock_bh(&r->lock); + } + return 0; +} + +/** + * ref_unlock - unlock referenced object + */ + +static inline void ref_unlock(u32 ref) +{ + if (likely(ref_table.entries)) { + struct reference *r = + &ref_table.entries[ref & ref_table.index_mask]; + + if (likely(r->data.reference == ref)) + spin_unlock_bh(&r->lock); + else + err("ref_unlock() invoked using obsolete reference\n"); + } +} + +/** + * ref_deref - return pointer referenced object (without locking it) + */ + +static inline void *ref_deref(u32 ref) +{ + if (likely(ref_table.entries)) { + struct reference *r = + &ref_table.entries[ref & ref_table.index_mask]; + + if (likely(r->data.reference == ref)) + return r->object; + } + return 0; +} + +#endif |