rculfhash: wait for call_rcu quiescence before destroy

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/rculfhash.c b/rculfhash.c
index 556ec36ddab261625d3c3b412496718c790d0c0b..a3223f37f046021cb6c3c0119e107e2e4dde4fd0 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -67,6 +67,7 @@ struct rcu_ht {
        ht_compare_fct compare_fct;
        unsigned long hash_seed;
        pthread_mutex_t resize_mutex;   /* resize mutex: add/del mutex */
+       unsigned int in_progress_resize;
        void (*ht_call_rcu)(struct rcu_head *head,
                      void (*func)(struct rcu_head *head));
 };
@@ -373,6 +374,7 @@ struct rcu_ht *ht_new(ht_hash_fct hash_fct,
        ht->compare_fct = compare_fct;
        ht->hash_seed = hash_seed;
        ht->ht_call_rcu = ht_call_rcu;
+       ht->in_progress_resize = 0;
        /* this mutex should not nest in read-side C.S. */
        pthread_mutex_init(&ht->resize_mutex, NULL);
        ht->t = calloc(1, sizeof(struct rcu_table)
@@ -477,6 +479,9 @@ int ht_destroy(struct rcu_ht *ht)
 {
        int ret;
 
+       /* Wait for in-flight resize operations to complete */
+       while (uatomic_read(&ht->in_progress_resize))
+               poll(NULL, 0, 100);     /* wait for 100ms */
        ret = ht_delete_dummy(ht);
        if (ret)
                return ret;
@@ -576,6 +581,8 @@ void do_resize_cb(struct rcu_head *head)
        _do_ht_resize(ht);
        pthread_mutex_unlock(&ht->resize_mutex);
        free(work);
+       cmm_smp_mb();   /* finish resize before decrement */
+       uatomic_dec(&ht->in_progress_resize);
 }
 
 static
@@ -586,6 +593,8 @@ void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth)
 
        target_size = resize_target_update(t, growth);
        if (!CMM_LOAD_SHARED(t->resize_initiated) && t->size < target_size) {
+               uatomic_inc(&ht->in_progress_resize);
+               cmm_smp_mb();   /* increment resize count before calling it */
                work = malloc(sizeof(*work));
                work->ht = ht;
                ht->ht_call_rcu(&work->head, do_resize_cb);