Fix: take RCU read-side lock within hash table functions

[lttng-tools.git] / src / common / hashtable / hashtable.c

diff --git a/src/common/hashtable/hashtable.c b/src/common/hashtable/hashtable.c
index 263df46839d37af58e2efe66770f5e1833c90f0f..d1049d1e2b9dea53b9747a0bcaf8cea4108833cd 100644 (file)
--- a/src/common/hashtable/hashtable.c
+++ b/src/common/hashtable/hashtable.c
@@ -16,6 +16,7 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <assert.h>
 #include <string.h>
 #include <urcu.h>
@@ -32,6 +33,13 @@ unsigned long lttng_ht_seed;
 static unsigned long min_hash_alloc_size = 1;
 static unsigned long max_hash_buckets_size = 0;
 
+/*
+ * Getter/lookup functions need to be called with RCU read-side lock
+ * held. However, modification functions (add, add_unique, replace, del)
+ * take the RCU lock internally, so it does not matter whether the
+ * caller hold the RCU lock or not.
+ */
+
 /*
  * Match function for string node.
  */
@@ -65,6 +73,17 @@ static int match_u64(struct cds_lfht_node *node, const void *key)
        return hash_match_key_u64(&match_node->key, (void *) key);
 }
 
+/*
+ * Match function for two uint64_t node.
+ */
+static int match_two_u64(struct cds_lfht_node *node, const void *key)
+{
+       struct lttng_ht_node_two_u64 *match_node =
+               caa_container_of(node, struct lttng_ht_node_two_u64, node);
+
+       return hash_match_key_two_u64((void *) &match_node->key, (void *) key);
+}
+
 /*
  * Return an allocated lttng hashtable.
  */
@@ -103,8 +122,13 @@ struct lttng_ht *lttng_ht_new(unsigned long size, int type)
                ht->match_fct = match_u64;
                ht->hash_fct = hash_key_u64;
                break;
+       case LTTNG_HT_TYPE_TWO_U64:
+               ht->match_fct = match_two_u64;
+               ht->hash_fct = hash_key_two_u64;
+               break;
        default:
                ERR("Unknown lttng hashtable type %d", type);
+               lttng_ht_destroy(ht);
                goto error;
        }
 
@@ -163,6 +187,19 @@ void lttng_ht_node_init_u64(struct lttng_ht_node_u64 *node,
        cds_lfht_node_init(&node->node);
 }
 
+/*
+ * Init lttng ht node with two uint64_t.
+ */
+void lttng_ht_node_init_two_u64(struct lttng_ht_node_two_u64 *node,
+               uint64_t key1, uint64_t key2)
+{
+       assert(node);
+
+       node->key.key1 = key1;
+       node->key.key2 = key2;
+       cds_lfht_node_init(&node->node);
+}
+
 /*
  * Free lttng ht node string.
  */
@@ -184,7 +221,16 @@ void lttng_ht_node_free_ulong(struct lttng_ht_node_ulong *node)
 /*
  * Free lttng ht node uint64_t.
  */
-void lttng_ht_node_free_u64(struct lttng_ht_node_ulong *node)
+void lttng_ht_node_free_u64(struct lttng_ht_node_u64 *node)
+{
+       assert(node);
+       free(node);
+}
+
+/*
+ * Free lttng ht node two uint64_t.
+ */
+void lttng_ht_node_free_two_u64(struct lttng_ht_node_two_u64 *node)
 {
        assert(node);
        free(node);
@@ -214,11 +260,31 @@ void lttng_ht_add_unique_str(struct lttng_ht *ht,
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        node_ptr = cds_lfht_add_unique(ht->ht, ht->hash_fct(node->key, lttng_ht_seed),
                        ht->match_fct, node->key, &node->node);
+       rcu_read_unlock();
        assert(node_ptr == &node->node);
 }
 
+/*
+ * Add string node to hashtable.
+ */
+void lttng_ht_add_str(struct lttng_ht *ht,
+               struct lttng_ht_node_str *node)
+{
+       assert(ht);
+       assert(ht->ht);
+       assert(node);
+
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
+       cds_lfht_add(ht->ht, ht->hash_fct(node->key, lttng_ht_seed),
+                       &node->node);
+       rcu_read_unlock();
+}
+
 /*
  * Add unsigned long node to hashtable.
  */
@@ -228,8 +294,11 @@ void lttng_ht_add_ulong(struct lttng_ht *ht, struct lttng_ht_node_ulong *node)
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        cds_lfht_add(ht->ht, ht->hash_fct((void *) node->key, lttng_ht_seed),
                        &node->node);
+       rcu_read_unlock();
 }
 
 /*
@@ -242,8 +311,11 @@ void lttng_ht_add_u64(struct lttng_ht *ht, struct lttng_ht_node_u64 *node)
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        cds_lfht_add(ht->ht, ht->hash_fct(&node->key, lttng_ht_seed),
                        &node->node);
+       rcu_read_unlock();
 }
 
 /*
@@ -257,9 +329,12 @@ void lttng_ht_add_unique_ulong(struct lttng_ht *ht,
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        node_ptr = cds_lfht_add_unique(ht->ht,
                        ht->hash_fct((void *) node->key, lttng_ht_seed), ht->match_fct,
                        (void *) node->key, &node->node);
+       rcu_read_unlock();
        assert(node_ptr == &node->node);
 }
 
@@ -274,9 +349,32 @@ void lttng_ht_add_unique_u64(struct lttng_ht *ht,
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        node_ptr = cds_lfht_add_unique(ht->ht,
                        ht->hash_fct(&node->key, lttng_ht_seed), ht->match_fct,
                        &node->key, &node->node);
+       rcu_read_unlock();
+       assert(node_ptr == &node->node);
+}
+
+/*
+ * Add unique two uint64_t node to hashtable.
+ */
+void lttng_ht_add_unique_two_u64(struct lttng_ht *ht,
+               struct lttng_ht_node_two_u64 *node)
+{
+       struct cds_lfht_node *node_ptr;
+       assert(ht);
+       assert(ht->ht);
+       assert(node);
+
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
+       node_ptr = cds_lfht_add_unique(ht->ht,
+                       ht->hash_fct((void *) &node->key, lttng_ht_seed), ht->match_fct,
+                       (void *) &node->key, &node->node);
+       rcu_read_unlock();
        assert(node_ptr == &node->node);
 }
 
@@ -291,9 +389,12 @@ struct lttng_ht_node_ulong *lttng_ht_add_replace_ulong(struct lttng_ht *ht,
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        node_ptr = cds_lfht_add_replace(ht->ht,
                        ht->hash_fct((void *) node->key, lttng_ht_seed), ht->match_fct,
                        (void *) node->key, &node->node);
+       rcu_read_unlock();
        if (!node_ptr) {
                return NULL;
        } else {
@@ -313,9 +414,12 @@ struct lttng_ht_node_u64 *lttng_ht_add_replace_u64(struct lttng_ht *ht,
        assert(ht->ht);
        assert(node);
 
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
        node_ptr = cds_lfht_add_replace(ht->ht,
                        ht->hash_fct(&node->key, lttng_ht_seed), ht->match_fct,
                        &node->key, &node->node);
+       rcu_read_unlock();
        if (!node_ptr) {
                return NULL;
        } else {
@@ -329,11 +433,17 @@ struct lttng_ht_node_u64 *lttng_ht_add_replace_u64(struct lttng_ht *ht,
  */
 int lttng_ht_del(struct lttng_ht *ht, struct lttng_ht_iter *iter)
 {
+       int ret;
+
        assert(ht);
        assert(ht->ht);
        assert(iter);
 
-       return cds_lfht_del(ht->ht, iter->iter.node);
+       /* RCU read lock protects from ABA. */
+       rcu_read_lock();
+       ret = cds_lfht_del(ht->ht, iter->iter.node);
+       rcu_read_unlock();
+       return ret;
 }
 
 /*
@@ -371,7 +481,10 @@ unsigned long lttng_ht_get_count(struct lttng_ht *ht)
        assert(ht);
        assert(ht->ht);
 
+       /* RCU read lock protects from ABA and allows RCU traversal. */
+       rcu_read_lock();
        cds_lfht_count_nodes(ht->ht, &scb, &count, &sca);
+       rcu_read_unlock();
 
        return count;
 }
@@ -424,6 +537,22 @@ struct lttng_ht_node_u64 *lttng_ht_iter_get_node_u64(
        return caa_container_of(node, struct lttng_ht_node_u64, node);
 }
 
+/*
+ * Return lttng ht stream and index id node from iterator.
+ */
+struct lttng_ht_node_two_u64 *lttng_ht_iter_get_node_two_u64(
+               struct lttng_ht_iter *iter)
+{
+       struct cds_lfht_node *node;
+
+       assert(iter);
+       node = cds_lfht_iter_get_node(&iter->iter);
+       if (!node) {
+               return NULL;
+       }
+       return caa_container_of(node, struct lttng_ht_node_two_u64, node);
+}
+
 /*
  * lib constructor
  */