X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=net%2Ftipc%2Fref.c;h=a101de86824d2b1db6e485775d1d1def6bf2c1b7;hb=8642bd9e04f51980b2b6293c66acf7e388c9a6e7;hp=6704a58c785162e40989711bd061c44e6b8f25e8;hpb=60f29b1e1600d89aee5e529acb4b276a6650cb8b;p=linux-2.6 diff --git a/net/tipc/ref.c b/net/tipc/ref.c index 6704a58c78..a101de8682 100644 --- a/net/tipc/ref.c +++ b/net/tipc/ref.c @@ -2,7 +2,7 @@ * net/tipc/ref.c: TIPC object registry code * * Copyright (c) 1991-2006, Ericsson AB - * Copyright (c) 2004-2005, Wind River Systems + * Copyright (c) 2004-2007, Wind River Systems * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -36,32 +36,60 @@ #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" + +/** + * struct reference - TIPC object reference entry + * @object: pointer to object associated with reference entry + * @lock: spinlock controlling access to object + * @ref: reference value for object (combines instance & array index info) + */ + +struct reference { + void *object; + spinlock_t lock; + u32 ref; +}; + +/** + * struct tipc_ref_table - table of TIPC object reference entries + * @entries: pointer to array of reference entries + * @capacity: array index of first unusable entry + * @init_point: array index of first uninitialized entry + * @first_free: array index of first unused object reference entry + * @last_free: array index of last unused object reference entry + * @index_mask: bitmask for array index portion of reference values + * @start_mask: initial value for instance value portion of reference values + */ + +struct ref_table { + struct reference *entries; + u32 capacity; + u32 init_point; + u32 first_free; + u32 last_free; + u32 index_mask; + u32 start_mask; +}; /* * 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) + * State Object ptr Reference + * ----- ---------- --------- + * In use non-NULL XXXX|own index + * (XXXX changes each time entry is acquired) + * Free NULL YYYY|next free index + * (YYYY is one more than last used XXXX) + * Uninitialized NULL 0 * - * 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. + * Entry 0 is not used; this allows index 0 to denote 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. + * Note that a reference value of 0 does not necessarily indicate that an + * entry is uninitialized, since the last entry in the free list could also + * have a reference value of 0 (although this is unlikely). */ -struct ref_table tipc_ref_table = { NULL }; +static struct ref_table tipc_ref_table = { NULL }; static DEFINE_RWLOCK(ref_table_lock); @@ -72,29 +100,29 @@ static DEFINE_RWLOCK(ref_table_lock); int tipc_ref_table_init(u32 requested_size, u32 start) { struct reference *table; - u32 sz = 1 << 4; - u32 index_mask; - int i; + u32 actual_size; - while (sz < requested_size) { - sz <<= 1; - } - table = vmalloc(sz * sizeof(*table)); + /* account for unused entry, then round up size to a power of 2 */ + + requested_size++; + for (actual_size = 16; actual_size < requested_size; actual_size <<= 1) + /* do nothing */ ; + + /* allocate table & mark all entries as uninitialized */ + + table = __vmalloc(actual_size * sizeof(struct reference), + GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL); 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 = NULL; - spin_lock_init(&table[i].lock); - 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); + tipc_ref_table.capacity = requested_size; + tipc_ref_table.init_point = 1; + tipc_ref_table.first_free = 0; + tipc_ref_table.last_free = 0; + tipc_ref_table.index_mask = actual_size - 1; + tipc_ref_table.start_mask = start & ~tipc_ref_table.index_mask; + return TIPC_OK; } @@ -114,9 +142,13 @@ void tipc_ref_table_stop(void) /** * 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. + * Register an object pointer in reference table and lock the object. + * Returns a unique reference value that is used from then on to retrieve the + * object pointer, or to determine that the object has been deregistered. + * + * Note: The object is returned in the locked state so that the caller can + * register a partially initialized object, without running the risk that + * the object will be accessed before initialization is complete. */ u32 tipc_ref_acquire(void *object, spinlock_t **lock) @@ -125,7 +157,7 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock) u32 index; u32 index_mask; u32 next_plus_upper; - u32 reference = 0; + u32 ref; if (!object) { err("Attempt to acquire reference to non-existent object\n"); @@ -136,6 +168,8 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock) return 0; } + /* take a free entry, if available; otherwise initialize a new entry */ + write_lock_bh(&ref_table_lock); if (tipc_ref_table.first_free) { index = tipc_ref_table.first_free; @@ -143,17 +177,29 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock) 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; + next_plus_upper = entry->ref; tipc_ref_table.first_free = next_plus_upper & index_mask; - reference = (next_plus_upper & ~index_mask) + index; - entry->data.reference = reference; + ref = (next_plus_upper & ~index_mask) + index; + entry->ref = ref; + entry->object = object; + *lock = &entry->lock; + } + else if (tipc_ref_table.init_point < tipc_ref_table.capacity) { + index = tipc_ref_table.init_point++; + entry = &(tipc_ref_table.entries[index]); + spin_lock_init(&entry->lock); + spin_lock_bh(&entry->lock); + ref = tipc_ref_table.start_mask + index; + entry->ref = ref; entry->object = object; - if (lock != 0) - *lock = &entry->lock; - spin_unlock_bh(&entry->lock); + *lock = &entry->lock; + } + else { + ref = 0; } write_unlock_bh(&ref_table_lock); - return reference; + + return ref; } /** @@ -169,42 +215,99 @@ void tipc_ref_discard(u32 ref) u32 index; u32 index_mask; - if (!ref) { - err("Attempt to discard reference 0\n"); - return; - } if (!tipc_ref_table.entries) { err("Reference table not found during discard attempt\n"); return; } - write_lock_bh(&ref_table_lock); index_mask = tipc_ref_table.index_mask; index = ref & index_mask; entry = &(tipc_ref_table.entries[index]); + write_lock_bh(&ref_table_lock); + if (!entry->object) { err("Attempt to discard reference to non-existent object\n"); goto exit; } - if (entry->data.reference != ref) { + if (entry->ref != ref) { err("Attempt to discard non-existent reference\n"); goto exit; } - /* mark entry as unused */ + /* + * mark entry as unused; increment instance part of entry's reference + * to invalidate any subsequent references + */ + entry->object = NULL; + entry->ref = (ref & ~index_mask) + (index_mask + 1); + + /* append entry to free entry list */ + 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.entries[tipc_ref_table.last_free].ref |= 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); exit: write_unlock_bh(&ref_table_lock); } +/** + * tipc_ref_lock - lock referenced object and return pointer to it + */ + +void *tipc_ref_lock(u32 ref) +{ + if (likely(tipc_ref_table.entries)) { + struct reference *entry; + + entry = &tipc_ref_table.entries[ref & + tipc_ref_table.index_mask]; + if (likely(entry->ref != 0)) { + spin_lock_bh(&entry->lock); + if (likely((entry->ref == ref) && (entry->object))) + return entry->object; + spin_unlock_bh(&entry->lock); + } + } + return NULL; +} + +/** + * tipc_ref_unlock - unlock referenced object + */ + +void tipc_ref_unlock(u32 ref) +{ + if (likely(tipc_ref_table.entries)) { + struct reference *entry; + + entry = &tipc_ref_table.entries[ref & + tipc_ref_table.index_mask]; + if (likely((entry->ref == ref) && (entry->object))) + spin_unlock_bh(&entry->lock); + else + err("Attempt to unlock non-existent reference\n"); + } +} + +/** + * tipc_ref_deref - return pointer referenced object (without locking it) + */ + +void *tipc_ref_deref(u32 ref) +{ + if (likely(tipc_ref_table.entries)) { + struct reference *entry; + + entry = &tipc_ref_table.entries[ref & + tipc_ref_table.index_mask]; + if (likely(entry->ref == ref)) + return entry->object; + } + return NULL; +} +