rculfhash: detect if resize/destroy are called within RCU read-side C.S.

Report errors.

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

diff --git a/rculfhash.c b/rculfhash.c
index 6e12db1013f6c58d70ee3119a67a068fadc3d80e..423609d6c188dd79f6392763ad7b8082f2180def 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -1745,6 +1745,13 @@ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
        was_online = ht->flavor->read_ongoing();
        if (was_online)
                ht->flavor->thread_offline();
+       /* Calling with RCU read-side held is an error. */
+       if (ht->flavor->read_ongoing()) {
+               ret = -EINVAL;
+               if (was_online)
+                       ht->flavor->thread_online();
+               goto end;
+       }
        while (uatomic_read(&ht->in_progress_resize))
                poll(NULL, 0, 100);     /* wait for 100ms */
        if (was_online)
@@ -1756,6 +1763,7 @@ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
        if (attr)
                *attr = ht->resize_attr;
        poison_free(ht);
+end:
        return ret;
 }
 
@@ -1886,14 +1894,26 @@ void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size)
 {
        int was_online;
 
-       resize_target_update_count(ht, new_size);
-       CMM_STORE_SHARED(ht->resize_initiated, 1);
        was_online = ht->flavor->read_ongoing();
        if (was_online)
                ht->flavor->thread_offline();
+       /* Calling with RCU read-side held is an error. */
+       if (ht->flavor->read_ongoing()) {
+               static int print_once;
+
+               if (!CMM_LOAD_SHARED(print_once))
+                       fprintf(stderr, "[error] rculfhash: cds_lfht_resize "
+                               "called with RCU read-side lock held.\n");
+               CMM_STORE_SHARED(print_once, 1);
+               assert(0);
+               goto end;
+       }
+       resize_target_update_count(ht, new_size);
+       CMM_STORE_SHARED(ht->resize_initiated, 1);
        pthread_mutex_lock(&ht->resize_mutex);
        _do_cds_lfht_resize(ht);
        pthread_mutex_unlock(&ht->resize_mutex);
+end:
        if (was_online)
                ht->flavor->thread_online();
 }