Spelling cleanups within comments and documentation

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index b26a69085c35cbbf86d173193920c9e51f3b9e68..8c3d6218d1501cb567a3270b2db17c3ed9bc14b0 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -129,7 +129,7 @@
  *  - cds_lfht_first followed iteration with cds_lfht_next (and/or
  *    cds_lfht_next_duplicate, although less common).
  *
- * We define "write" operations as any of cds_lfht_add,
+ * We define "write" operations as any of cds_lfht_add, cds_lfht_replace,
  * cds_lfht_add_unique (success), cds_lfht_add_replace, cds_lfht_del.
  *
  * When cds_lfht_add_unique succeeds (returns the node passed as
@@ -281,7 +281,7 @@
  * Split-counters lazily update the global counter each 1024
  * addition/removal. It automatically keeps track of resize required.
  * We use the bucket length as indicator for need to expand for small
- * tables and machines lacking per-cpu data suppport.
+ * tables and machines lacking per-cpu data support.
  */
 #define COUNT_COMMIT_ORDER             10
 #define DEFAULT_SPLIT_COUNT_MASK       0xFUL
@@ -381,7 +381,8 @@ uint8_t bit_reverse_u8(uint8_t v)
        return BitReverseTable256[v];
 }
 
-static __attribute__((unused))
+#if (CAA_BITS_PER_LONG == 32)
+static
 uint32_t bit_reverse_u32(uint32_t v)
 {
        return ((uint32_t) bit_reverse_u8(v) << 24) | 
@@ -389,8 +390,8 @@ uint32_t bit_reverse_u32(uint32_t v)
                ((uint32_t) bit_reverse_u8(v >> 16) << 8) | 
                ((uint32_t) bit_reverse_u8(v >> 24));
 }
-
-static __attribute__((unused))
+#else
+static
 uint64_t bit_reverse_u64(uint64_t v)
 {
        return ((uint64_t) bit_reverse_u8(v) << 56) | 
@@ -402,6 +403,7 @@ uint64_t bit_reverse_u64(uint64_t v)
                ((uint64_t) bit_reverse_u8(v >> 48) << 8) |
                ((uint64_t) bit_reverse_u8(v >> 56));
 }
+#endif
 
 static
 unsigned long bit_reverse_ulong(unsigned long v)
@@ -589,8 +591,6 @@ static void ht_init_nr_cpus_mask(void)
 static
 void alloc_split_items_count(struct cds_lfht *ht)
 {
-       struct ht_items_count *count;
-
        if (nr_cpus_mask == -1) {
                ht_init_nr_cpus_mask();
                if (nr_cpus_mask < 0)
@@ -602,7 +602,8 @@ void alloc_split_items_count(struct cds_lfht *ht)
        assert(split_count_mask >= 0);
 
        if (ht->flags & CDS_LFHT_ACCOUNTING) {
-               ht->split_count = calloc(split_count_mask + 1, sizeof(*count));
+               ht->split_count = calloc(split_count_mask + 1,
+                                       sizeof(struct ht_items_count));
                assert(ht->split_count);
        } else {
                ht->split_count = NULL;
@@ -734,12 +735,6 @@ int is_removed(struct cds_lfht_node *node)
        return ((unsigned long) node) & REMOVED_FLAG;
 }
 
-static
-struct cds_lfht_node *flag_removed(struct cds_lfht_node *node)
-{
-       return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG);
-}
-
 static
 int is_bucket(struct cds_lfht_node *node)
 {
@@ -764,6 +759,12 @@ struct cds_lfht_node *flag_removal_owner(struct cds_lfht_node *node)
        return (struct cds_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG);
 }
 
+static
+struct cds_lfht_node *flag_removed_or_removal_owner(struct cds_lfht_node *node)
+{
+       return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG | REMOVAL_OWNER_FLAG);
+}
+
 static
 struct cds_lfht_node *get_end(void)
 {
@@ -894,6 +895,12 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
                }
                assert(old_next == clear_flag(old_next));
                assert(new_node != old_next);
+               /*
+                * REMOVAL_OWNER flag is _NEVER_ set before the REMOVED
+                * flag. It is either set atomically at the same time
+                * (replace) or after (del).
+                */
+               assert(!is_removal_owner(old_next));
                new_node->next = old_next;
                /*
                 * Here is the whole trick for lock-free replace: we add
@@ -906,10 +913,12 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
                 * the old node, but will not see the new one.
                 * This is a replacement of a node with another node
                 * that has the same value: we are therefore not
-                * removing a value from the hash table.
+                * removing a value from the hash table. We set both the
+                * REMOVED and REMOVAL_OWNER flags atomically so we own
+                * the node after successful cmpxchg.
                 */
                ret_next = uatomic_cmpxchg(&old_node->next,
-                             old_next, flag_removed(new_node));
+                       old_next, flag_removed_or_removal_owner(new_node));
                if (ret_next == old_next)
                        break;          /* We performed the replacement. */
                old_next = ret_next;
@@ -1065,6 +1074,11 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
        if (caa_unlikely(is_removed(next)))
                return -ENOENT;
        assert(!is_bucket(next));
+       /*
+        * The del operation semantic guarantees a full memory barrier
+        * before the uatomic_or atomic commit of the deletion flag.
+        */
+       cmm_smp_mb__before_uatomic_or();
        /*
         * We set the REMOVED_FLAG unconditionally. Note that there may
         * be more than one concurrent thread setting this flag.
@@ -1654,12 +1668,14 @@ int cds_lfht_replace(struct cds_lfht *ht,
 
 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node)
 {
-       unsigned long size, hash;
+       unsigned long size;
        int ret;
 
        size = rcu_dereference(ht->size);
        ret = _cds_lfht_del(ht, size, node);
        if (!ret) {
+               unsigned long hash;
+
                hash = bit_reverse_ulong(node->reverse_hash);
                ht_count_del(ht, size, hash);
        }
@@ -1715,8 +1731,10 @@ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
        /* Wait for in-flight resize operations to complete */
        _CMM_STORE_SHARED(ht->in_progress_destroy, 1);
        cmm_smp_mb();   /* Store destroy before load resize */
+       ht->flavor->thread_offline();
        while (uatomic_read(&ht->in_progress_resize))
                poll(NULL, 0, 100);     /* wait for 100ms */
+       ht->flavor->thread_online();
        ret = cds_lfht_delete_bucket(ht);
        if (ret)
                return ret;