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authorTom Herbert <tom@quantonium.net>2017-12-04 19:31:42 +0100
committerDavid S. Miller <davem@davemloft.net>2017-12-11 15:58:38 +0100
commit2db54b475ae918d274bfc276416c384ba95e9f94 (patch)
treec5e93acd923da0ed13d64dad38fc9d10ff25a229 /lib
parentrhashtable: Change rhashtable_walk_start to return void (diff)
downloadlinux-2db54b475ae918d274bfc276416c384ba95e9f94.tar.xz
linux-2db54b475ae918d274bfc276416c384ba95e9f94.zip
rhashtable: Add rhastable_walk_peek
This function is like rhashtable_walk_next except that it only returns the current element in the inter and does not advance the iter. This patch also creates __rhashtable_walk_find_next. It finds the next element in the table when the entry cached in iter is NULL or at the end of a slot. __rhashtable_walk_find_next is called from rhashtable_walk_next and rhastable_walk_peek. end_of_table is an added field to the iter structure. This indicates that the end of table was reached (walker.tbl being NULL is not a sufficient condition for end of table). Signed-off-by: Tom Herbert <tom@quantonium.net> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib')
-rw-r--r--lib/rhashtable.c103
1 files changed, 87 insertions, 16 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 1935e86ed477..6fc52d82efe6 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -707,6 +707,7 @@ void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter)
iter->p = NULL;
iter->slot = 0;
iter->skip = 0;
+ iter->end_of_table = 0;
spin_lock(&ht->lock);
iter->walker.tbl =
@@ -761,7 +762,7 @@ int rhashtable_walk_start_check(struct rhashtable_iter *iter)
list_del(&iter->walker.list);
spin_unlock(&ht->lock);
- if (!iter->walker.tbl) {
+ if (!iter->walker.tbl && !iter->end_of_table) {
iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht);
return -EAGAIN;
}
@@ -771,18 +772,16 @@ int rhashtable_walk_start_check(struct rhashtable_iter *iter)
EXPORT_SYMBOL_GPL(rhashtable_walk_start_check);
/**
- * rhashtable_walk_next - Return the next object and advance the iterator
+ * __rhashtable_walk_find_next - Find the next element in a table (or the first
+ * one in case of a new walk).
+ *
* @iter: Hash table iterator
*
- * Note that you must call rhashtable_walk_stop when you are finished
- * with the walk.
+ * Returns the found object or NULL when the end of the table is reached.
*
- * Returns the next object or NULL when the end of the table is reached.
- *
- * Returns -EAGAIN if resize event occured. Note that the iterator
- * will rewind back to the beginning and you may continue to use it.
+ * Returns -EAGAIN if resize event occurred.
*/
-void *rhashtable_walk_next(struct rhashtable_iter *iter)
+static void *__rhashtable_walk_find_next(struct rhashtable_iter *iter)
{
struct bucket_table *tbl = iter->walker.tbl;
struct rhlist_head *list = iter->list;
@@ -790,13 +789,8 @@ void *rhashtable_walk_next(struct rhashtable_iter *iter)
struct rhash_head *p = iter->p;
bool rhlist = ht->rhlist;
- if (p) {
- if (!rhlist || !(list = rcu_dereference(list->next))) {
- p = rcu_dereference(p->next);
- list = container_of(p, struct rhlist_head, rhead);
- }
- goto next;
- }
+ if (!tbl)
+ return NULL;
for (; iter->slot < tbl->size; iter->slot++) {
int skip = iter->skip;
@@ -840,13 +834,90 @@ next:
iter->slot = 0;
iter->skip = 0;
return ERR_PTR(-EAGAIN);
+ } else {
+ iter->end_of_table = true;
}
return NULL;
}
+
+/**
+ * rhashtable_walk_next - Return the next object and advance the iterator
+ * @iter: Hash table iterator
+ *
+ * Note that you must call rhashtable_walk_stop when you are finished
+ * with the walk.
+ *
+ * Returns the next object or NULL when the end of the table is reached.
+ *
+ * Returns -EAGAIN if resize event occurred. Note that the iterator
+ * will rewind back to the beginning and you may continue to use it.
+ */
+void *rhashtable_walk_next(struct rhashtable_iter *iter)
+{
+ struct rhlist_head *list = iter->list;
+ struct rhashtable *ht = iter->ht;
+ struct rhash_head *p = iter->p;
+ bool rhlist = ht->rhlist;
+
+ if (p) {
+ if (!rhlist || !(list = rcu_dereference(list->next))) {
+ p = rcu_dereference(p->next);
+ list = container_of(p, struct rhlist_head, rhead);
+ }
+ if (!rht_is_a_nulls(p)) {
+ iter->skip++;
+ iter->p = p;
+ iter->list = list;
+ return rht_obj(ht, rhlist ? &list->rhead : p);
+ }
+
+ /* At the end of this slot, switch to next one and then find
+ * next entry from that point.
+ */
+ iter->skip = 0;
+ iter->slot++;
+ }
+
+ return __rhashtable_walk_find_next(iter);
+}
EXPORT_SYMBOL_GPL(rhashtable_walk_next);
/**
+ * rhashtable_walk_peek - Return the next object but don't advance the iterator
+ * @iter: Hash table iterator
+ *
+ * Returns the next object or NULL when the end of the table is reached.
+ *
+ * Returns -EAGAIN if resize event occurred. Note that the iterator
+ * will rewind back to the beginning and you may continue to use it.
+ */
+void *rhashtable_walk_peek(struct rhashtable_iter *iter)
+{
+ struct rhlist_head *list = iter->list;
+ struct rhashtable *ht = iter->ht;
+ struct rhash_head *p = iter->p;
+
+ if (p)
+ return rht_obj(ht, ht->rhlist ? &list->rhead : p);
+
+ /* No object found in current iter, find next one in the table. */
+
+ if (iter->skip) {
+ /* A nonzero skip value points to the next entry in the table
+ * beyond that last one that was found. Decrement skip so
+ * we find the current value. __rhashtable_walk_find_next
+ * will restore the original value of skip assuming that
+ * the table hasn't changed.
+ */
+ iter->skip--;
+ }
+
+ return __rhashtable_walk_find_next(iter);
+}
+EXPORT_SYMBOL_GPL(rhashtable_walk_peek);
+
+/**
* rhashtable_walk_stop - Finish a hash table walk
* @iter: Hash table iterator
*