From 4d676753007f54e45b7e0307244ffc876a953874 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 13 Sep 2011 20:33:15 -0400 Subject: [PATCH] rculfhash: break in-progress resize when target size change (between levels) Signed-off-by: Mathieu Desnoyers --- rculfhash.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) diff --git a/rculfhash.c b/rculfhash.c index ce09a0f..1288c78 100644 --- a/rculfhash.c +++ b/rculfhash.c @@ -959,6 +959,11 @@ void init_table(struct cds_lfht *ht, len = !i ? 1 : 1UL << (i - 1); dbg_printf("init order %lu len: %lu\n", i, len); + + /* Stop expand if the resize target changes under us */ + if (CMM_LOAD_SHARED(ht->t.resize_target) < (!i ? 1 : (1UL << i))) + break; + ht->t.tbl[i] = calloc(1, sizeof(struct rcu_level) + (len * sizeof(struct _cds_lfht_node))); @@ -1040,13 +1045,27 @@ void fini_table(struct cds_lfht *ht, first_order, first_order + len_order); end_order = first_order + len_order; assert(first_order > 0); - assert(ht->t.size == (1UL << (first_order - 1))); for (i = end_order - 1; i >= first_order; i--) { unsigned long len; len = !i ? 1 : 1UL << (i - 1); dbg_printf("fini order %lu len: %lu\n", i, len); + /* Stop shrink if the resize target changes under us */ + if (CMM_LOAD_SHARED(ht->t.resize_target) > (1UL << (i - 1))) + break; + + cmm_smp_wmb(); /* populate data before RCU size */ + CMM_STORE_SHARED(ht->t.size, 1UL << (i - 1)); + + /* + * We need to wait for all add operations to reach Q.S. (and + * thus use the new table for lookups) before we can start + * releasing the old dummy nodes. Otherwise their lookup will + * return a logically removed node as insert position. + */ + ht->cds_lfht_synchronize_rcu(); + /* * Set "removed" flag in dummy nodes about to be removed. * Unlink all now-logically-removed dummy node pointers. @@ -1099,6 +1118,7 @@ struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct, ht->flags = flags; ht->cds_lfht_rcu_thread_offline(); pthread_mutex_lock(&ht->resize_mutex); + ht->t.resize_target = 1UL << (order - 1); init_table(ht, 0, order); pthread_mutex_unlock(&ht->resize_mutex); ht->cds_lfht_rcu_thread_online(); @@ -1327,17 +1347,6 @@ void _do_cds_lfht_shrink(struct cds_lfht *ht, old_size, old_order, new_size, new_order); assert(new_size < old_size); - cmm_smp_wmb(); /* populate data before RCU size */ - CMM_STORE_SHARED(ht->t.size, new_size); - - /* - * We need to wait for all add operations to reach Q.S. (and - * thus use the new table for lookups) before we can start - * releasing the old dummy nodes. Otherwise their lookup will - * return a logically removed node as insert position. - */ - ht->cds_lfht_synchronize_rcu(); - /* Remove and unlink all dummy nodes to remove. */ fini_table(ht, new_order, old_order - new_order); } @@ -1363,7 +1372,7 @@ void _do_cds_lfht_resize(struct cds_lfht *ht) ht->t.resize_initiated = 0; /* write resize_initiated before read resize_target */ cmm_smp_mb(); - } while (new_size != CMM_LOAD_SHARED(ht->t.resize_target)); + } while (ht->t.size != CMM_LOAD_SHARED(ht->t.resize_target)); } static -- 2.34.1