Hi, Mathieu, Does any path need to be resent/respinned in previous round? Don't forgot the two patches followed by this round.
Thank, Lai On 10/27/2011 12:31 PM, Mathieu Desnoyers wrote: > I merged a significantly re-worked version of this patch. Thanks for > pointing out that the replacement could re-use the uniquify code path! > > Mathieu > > commit 83beee94416bdffdec505bc33cfd79859f6aa243 > Author: Mathieu Desnoyers <[email protected]> > Date: Thu Oct 27 06:30:49 2011 +0200 > > Move replace code out from _cds_lfht_add() > > Original patch from Lai Jiangshan, reworked significantly to keep the > iterator semantic, where a "next" node is never re-read after being > looked up within a RCU read-side critical section after it has been > validated. > > Although strictly speaking the "replace" code re-checks that the next > node is not logically removed with a cmpxchg, I prefer to ensure that > all lookup paths behave similarly. It will make it easier to track > behavior later on if they all follow the same rules. > > Reported-by: Lai Jiangshan <[email protected]> > Signed-off-by: Mathieu Desnoyers <[email protected]> > > diff --git a/rculfhash.c b/rculfhash.c > index be995df..b9c184f 100644 > --- a/rculfhash.c > +++ b/rculfhash.c > @@ -262,17 +262,12 @@ struct partition_resize_work { > unsigned long start, unsigned long len); > }; > > -enum add_mode { > - ADD_DEFAULT = 0, > - ADD_UNIQUE = 1, > - ADD_REPLACE = 2, > -}; > - > static > -struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, > - unsigned long size, > - struct cds_lfht_node *node, > - enum add_mode mode, int dummy); > +void _cds_lfht_add(struct cds_lfht *ht, > + unsigned long size, > + struct cds_lfht_node *node, > + struct cds_lfht_iter *unique_ret, > + int dummy); > > /* > * Algorithm to reverse bits in a word by lookup table, extended to > @@ -855,11 +850,16 @@ end: > } > } > > +/* > + * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add > + * mode. A NULL unique_ret allows creation of duplicate keys. > + */ > static > -struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, > - unsigned long size, > - struct cds_lfht_node *node, > - enum add_mode mode, int dummy) > +void _cds_lfht_add(struct cds_lfht *ht, > + unsigned long size, > + struct cds_lfht_node *node, > + struct cds_lfht_iter *unique_ret, > + int dummy) > { > struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next, > *return_node; > @@ -869,8 +869,9 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, > assert(!is_removed(node)); > if (!size) { > assert(dummy); > + assert(!unique_ret); > node->p.next = flag_dummy(get_end()); > - return node; /* Initial first add (head) */ > + return; /* Initial first add (head) */ > } > lookup = lookup_bucket(ht, size, > bit_reverse_ulong(node->p.reverse_hash)); > for (;;) { > @@ -895,16 +896,15 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, > next = rcu_dereference(clear_flag(iter)->p.next); > if (unlikely(is_removed(next))) > goto gc_node; > - if ((mode == ADD_UNIQUE || mode == ADD_REPLACE) > + if (unique_ret > && !is_dummy(next) > && clear_flag(iter)->p.reverse_hash == > node->p.reverse_hash > && !ht->compare_fct(node->key, node->key_len, > clear_flag(iter)->key, > clear_flag(iter)->key_len)) { > - if (mode == ADD_UNIQUE) > - return clear_flag(iter); > - else /* mode == ADD_REPLACE */ > - goto replace; > + unique_ret->node = clear_flag(iter); > + unique_ret->next = next; > + return; > } > /* Only account for identical reverse hash once */ > if (iter_prev->p.reverse_hash != > clear_flag(iter)->p.reverse_hash > @@ -931,23 +931,10 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, > new_node) != iter) { > continue; /* retry */ > } else { > - if (mode == ADD_REPLACE) > - return_node = NULL; > - else /* ADD_DEFAULT and ADD_UNIQUE */ > - return_node = node; > + return_node = node; > goto end; > } > > - replace: > - > - if (!_cds_lfht_replace(ht, size, clear_flag(iter), next, > - node)) { > - return_node = clear_flag(iter); > - goto end; /* gc already done */ > - } else { > - continue; /* retry */ > - } > - > gc_node: > assert(!is_removed(iter)); > if (is_dummy(iter)) > @@ -958,7 +945,10 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, > /* retry */ > } > end: > - return return_node; > + if (unique_ret) { > + unique_ret->node = return_node; > + /* unique_ret->next left unset, never used. */ > + } > } > > static > @@ -1094,8 +1084,8 @@ void init_table_populate_partition(struct cds_lfht *ht, > unsigned long i, > i, j, !i ? 0 : (1UL << (i - 1)) + j); > new_node->p.reverse_hash = > bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); > - (void) _cds_lfht_add(ht, !i ? 0 : (1UL << (i - 1)), > - new_node, ADD_DEFAULT, 1); > + _cds_lfht_add(ht, !i ? 0 : (1UL << (i - 1)), > + new_node, NULL, 1); > } > ht->cds_lfht_rcu_read_unlock(); > } > @@ -1437,7 +1427,7 @@ void cds_lfht_add(struct cds_lfht *ht, struct > cds_lfht_node *node) > node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); > > size = rcu_dereference(ht->t.size); > - (void) _cds_lfht_add(ht, size, node, ADD_DEFAULT, 0); > + _cds_lfht_add(ht, size, node, NULL, 0); > ht_count_add(ht, size); > } > > @@ -1445,32 +1435,38 @@ struct cds_lfht_node *cds_lfht_add_unique(struct > cds_lfht *ht, > struct cds_lfht_node *node) > { > unsigned long hash, size; > - struct cds_lfht_node *ret; > + struct cds_lfht_iter iter; > > hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); > node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); > > size = rcu_dereference(ht->t.size); > - ret = _cds_lfht_add(ht, size, node, ADD_UNIQUE, 0); > - if (ret == node) > + _cds_lfht_add(ht, size, node, &iter, 0); > + if (iter.node == node) > ht_count_add(ht, size); > - return ret; > + return iter.node; > } > > struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, > struct cds_lfht_node *node) > { > unsigned long hash, size; > - struct cds_lfht_node *ret; > + struct cds_lfht_iter iter; > > hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); > node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); > > size = rcu_dereference(ht->t.size); > - ret = _cds_lfht_add(ht, size, node, ADD_REPLACE, 0); > - if (ret == NULL) > - ht_count_add(ht, size); > - return ret; > + for (;;) { > + _cds_lfht_add(ht, size, node, &iter, 0); > + if (iter.node == node) { > + ht_count_add(ht, size); > + return NULL; > + } > + > + if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node)) > + return iter.node; > + } > } > > int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
