X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=rculfhash.c;h=c3a032e20d26a35c09d1f1b3c466432206ecbd32;hb=01dbfa62037e08aa2d08ab0e721267ccdd99b947;hp=ee4bea24c11340e5253612c51fad50c891020622;hpb=98808fb1581997fc7c9ff1bd6a486ceb27932be1;p=urcu.git

diff --git a/rculfhash.c b/rculfhash.c
index ee4bea2..c3a032e 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -220,6 +220,8 @@ struct cds_lfht {
 	void (*cds_lfht_call_rcu)(struct rcu_head *head,
 		      void (*func)(struct rcu_head *head));
 	void (*cds_lfht_synchronize_rcu)(void);
+	void (*cds_lfht_rcu_read_lock)(void);
+	void (*cds_lfht_rcu_read_unlock)(void);
 	unsigned long count;		/* global approximate item count */
 	struct ht_items_count *percpu_count;	/* per-cpu item count */
 };
@@ -675,15 +677,20 @@ static
 void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node)
 {
 	struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
+	struct cds_lfht_node *iter_trace[64];
+	unsigned long trace_idx = 0;
 
+	memset(iter_trace, 0, sizeof(iter_trace));
 	assert(!is_dummy(dummy));
 	assert(!is_removed(dummy));
 	assert(!is_dummy(node));
 	assert(!is_removed(node));
 	for (;;) {
+		iter_trace[trace_idx++ & (64 - 1)] = (void *) 0x1;
 		iter_prev = dummy;
 		/* We can always skip the dummy node initially */
 		iter = rcu_dereference(iter_prev->p.next);
+		iter_trace[trace_idx++ & (64 - 1)] = iter;
 		assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
 		/*
 		 * We should never be called with dummy (start of chain)
@@ -702,6 +709,7 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node
 				break;
 			iter_prev = clear_flag(iter);
 			iter = next;
+			iter_trace[trace_idx++ & (64 - 1)] = iter;
 		}
 		assert(!is_removed(iter));
 		if (is_dummy(iter))
@@ -709,6 +717,7 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node
 		else
 			new_next = clear_flag(next);
 		(void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
+		iter_trace[trace_idx++ & (64 - 1)] = (void *) 0x2;
 	}
 }
 
@@ -855,6 +864,11 @@ end:
 		return -ENOENT;
 }
 
+/*
+ * Holding RCU read lock to protect _cds_lfht_add against memory
+ * reclaim that could be performed by other call_rcu worker threads (ABA
+ * problem).
+ */
 static
 void init_table(struct cds_lfht *ht, struct rcu_table *t,
 		unsigned long first_order, unsigned long len_order)
@@ -872,6 +886,7 @@ void init_table(struct cds_lfht *ht, struct rcu_table *t,
 		dbg_printf("init order %lu len: %lu\n", i, len);
 		t->tbl[i] = calloc(1, sizeof(struct rcu_level)
 				+ (len * sizeof(struct _cds_lfht_node)));
+		ht->cds_lfht_rcu_read_lock();
 		for (j = 0; j < len; j++) {
 			struct cds_lfht_node *new_node =
 				(struct cds_lfht_node *) &t->tbl[i]->nodes[j];
@@ -884,6 +899,7 @@ void init_table(struct cds_lfht *ht, struct rcu_table *t,
 			if (CMM_LOAD_SHARED(ht->in_progress_destroy))
 				break;
 		}
+		ht->cds_lfht_rcu_read_unlock();
 		/* Update table size */
 		t->size = !i ? 1 : (1UL << i);
 		dbg_printf("init new size: %lu\n", t->size);
@@ -894,6 +910,11 @@ void init_table(struct cds_lfht *ht, struct rcu_table *t,
 	t->resize_initiated = 0;
 }
 
+/*
+ * Holding RCU read lock to protect _cds_lfht_remove against memory
+ * reclaim that could be performed by other call_rcu worker threads (ABA
+ * problem).
+ */
 static
 void fini_table(struct cds_lfht *ht, struct rcu_table *t,
 		unsigned long first_order, unsigned long len_order)
@@ -917,6 +938,7 @@ void fini_table(struct cds_lfht *ht, struct rcu_table *t,
 		 */
 		t->size = 1UL << (i - 1);
 		/* Unlink */
+		ht->cds_lfht_rcu_read_lock();
 		for (j = 0; j < len; j++) {
 			struct cds_lfht_node *fini_node =
 				(struct cds_lfht_node *) &t->tbl[i]->nodes[j];
@@ -929,6 +951,7 @@ void fini_table(struct cds_lfht *ht, struct rcu_table *t,
 			if (CMM_LOAD_SHARED(ht->in_progress_destroy))
 				break;
 		}
+		ht->cds_lfht_rcu_read_unlock();
 		ht->cds_lfht_call_rcu(&t->tbl[i]->head, cds_lfht_free_level);
 		dbg_printf("fini new size: %lu\n", t->size);
 		if (CMM_LOAD_SHARED(ht->in_progress_destroy))
@@ -945,7 +968,9 @@ struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
 			int flags,
 			void (*cds_lfht_call_rcu)(struct rcu_head *head,
 					void (*func)(struct rcu_head *head)),
-			void (*cds_lfht_synchronize_rcu)(void))
+			void (*cds_lfht_synchronize_rcu)(void),
+			void (*cds_lfht_rcu_read_lock)(void),
+			void (*cds_lfht_rcu_read_unlock)(void))
 {
 	struct cds_lfht *ht;
 	unsigned long order;
@@ -959,6 +984,8 @@ struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
 	ht->hash_seed = hash_seed;
 	ht->cds_lfht_call_rcu = cds_lfht_call_rcu;
 	ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu;
+	ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock;
+	ht->cds_lfht_rcu_read_unlock = cds_lfht_rcu_read_unlock;
 	ht->in_progress_resize = 0;
 	ht->percpu_count = alloc_per_cpu_items_count();
 	/* this mutex should not nest in read-side C.S. */