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wfcqueue: remove ancient comment
[urcu.git]
/
rculfhash.c
diff --git
a/rculfhash.c
b/rculfhash.c
index 827c2956b217e6bf00c839744f057142deade1cf..b8fbb6481d9291a6226f2200f8374b810ffd34af 100644
(file)
--- a/
rculfhash.c
+++ b/
rculfhash.c
@@
-110,7
+110,7
@@
* each the same number of buckets.
* - The RCU "mmap" memory backend uses a single memory map to hold
* all buckets.
* each the same number of buckets.
* - The RCU "mmap" memory backend uses a single memory map to hold
* all buckets.
- * - synchron
zi
e_rcu is used to garbage-collect the old bucket node table.
+ * - synchron
iz
e_rcu is used to garbage-collect the old bucket node table.
*
* Ordering Guarantees:
*
*
* Ordering Guarantees:
*
@@
-734,12
+734,6
@@
int is_removed(struct cds_lfht_node *node)
return ((unsigned long) node) & REMOVED_FLAG;
}
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)
{
static
int is_bucket(struct cds_lfht_node *node)
{
@@
-764,6
+758,12
@@
struct cds_lfht_node *flag_removal_owner(struct cds_lfht_node *node)
return (struct cds_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG);
}
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)
{
static
struct cds_lfht_node *get_end(void)
{
@@
-894,6
+894,12
@@
int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
}
assert(old_next == clear_flag(old_next));
assert(new_node != old_next);
}
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
new_node->next = old_next;
/*
* Here is the whole trick for lock-free replace: we add
@@
-906,10
+912,12
@@
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
* 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,
*/
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;
if (ret_next == old_next)
break; /* We performed the replacement. */
old_next = ret_next;
@@
-923,7
+931,7
@@
int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash));
_cds_lfht_gc_bucket(bucket, new_node);
bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash));
_cds_lfht_gc_bucket(bucket, new_node);
- assert(is_removed(
rcu_dereference
(old_node->next)));
+ assert(is_removed(
CMM_LOAD_SHARED
(old_node->next)));
return 0;
}
return 0;
}
@@
-1061,10
+1069,15
@@
int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
* logical removal flag). Return -ENOENT if the node had
* previously been removed.
*/
* logical removal flag). Return -ENOENT if the node had
* previously been removed.
*/
- next =
rcu_dereference(node->next);
+ next =
CMM_LOAD_SHARED(node->next); /* next is not dereferenced */
if (caa_unlikely(is_removed(next)))
return -ENOENT;
assert(!is_bucket(next));
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.
/*
* We set the REMOVED_FLAG unconditionally. Note that there may
* be more than one concurrent thread setting this flag.
@@
-1082,7
+1095,7
@@
int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
_cds_lfht_gc_bucket(bucket, node);
bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
_cds_lfht_gc_bucket(bucket, node);
- assert(is_removed(
rcu_dereference
(node->next)));
+ assert(is_removed(
CMM_LOAD_SHARED
(node->next)));
/*
* Last phase: atomically exchange node->next with a version
* having "REMOVAL_OWNER_FLAG" set. If the returned node->next
/*
* Last phase: atomically exchange node->next with a version
* having "REMOVAL_OWNER_FLAG" set. If the returned node->next
@@
-1510,7
+1523,7
@@
void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
}
node = clear_flag(next);
}
}
node = clear_flag(next);
}
- assert(!node || !is_bucket(
rcu_dereference
(node->next)));
+ assert(!node || !is_bucket(
CMM_LOAD_SHARED
(node->next)));
iter->node = node;
iter->next = next;
}
iter->node = node;
iter->next = next;
}
@@
-1543,7
+1556,7
@@
void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
}
node = clear_flag(next);
}
}
node = clear_flag(next);
}
- assert(!node || !is_bucket(
rcu_dereference
(node->next)));
+ assert(!node || !is_bucket(
CMM_LOAD_SHARED
(node->next)));
iter->node = node;
iter->next = next;
}
iter->node = node;
iter->next = next;
}
@@
-1565,7
+1578,7
@@
void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter)
}
node = clear_flag(next);
}
}
node = clear_flag(next);
}
- assert(!node || !is_bucket(
rcu_dereference
(node->next)));
+ assert(!node || !is_bucket(
CMM_LOAD_SHARED
(node->next)));
iter->node = node;
iter->next = next;
}
iter->node = node;
iter->next = next;
}
@@
-1668,7
+1681,7
@@
int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node)
int cds_lfht_is_node_deleted(struct cds_lfht_node *node)
{
int cds_lfht_is_node_deleted(struct cds_lfht_node *node)
{
- return is_removed(
rcu_dereference
(node->next));
+ return is_removed(
CMM_LOAD_SHARED
(node->next));
}
static
}
static
@@
-1715,8
+1728,10
@@
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 */
/* 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 */
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;
ret = cds_lfht_delete_bucket(ht);
if (ret)
return ret;
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