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Message-Id: <20171201000305.2392-3-tom@quantonium.net>
Date: Thu, 30 Nov 2017 16:03:02 -0800
From: Tom Herbert <tom@...ntonium.net>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, rohit@...ntonium.net,
herbert@...dor.apana.org.au, Tom Herbert <tom@...ntonium.net>
Subject: [PATCH net-next 2/5] 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.
Signed-off-by: Tom Herbert <tom@...ntonium.net>
---
include/linux/rhashtable.h | 1 +
lib/rhashtable.c | 103 ++++++++++++++++++++++++++++++++++++++-------
2 files changed, 88 insertions(+), 16 deletions(-)
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 4c976bf320a8..7f3e674e127a 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -380,6 +380,7 @@ void rhashtable_walk_enter(struct rhashtable *ht,
void rhashtable_walk_exit(struct rhashtable_iter *iter);
void rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU);
void *rhashtable_walk_next(struct rhashtable_iter *iter);
+void *rhashtable_walk_peek(struct rhashtable_iter *iter);
void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
void rhashtable_free_and_destroy(struct rhashtable *ht,
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index eeddfb3199cd..1d58231110af 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -753,18 +753,16 @@ void rhashtable_walk_start(struct rhashtable_iter *iter)
EXPORT_SYMBOL_GPL(rhashtable_walk_start);
/**
- * 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;
@@ -772,14 +770,6 @@ 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;
- }
-
for (; iter->slot < tbl->size; iter->slot++) {
int skip = iter->skip;
@@ -826,9 +816,90 @@ void *rhashtable_walk_next(struct rhashtable_iter *iter)
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 (!iter->walker.tbl)
+ return NULL;
+
+ 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 (!iter->walker.tbl)
+ return NULL;
+
+ 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
*
--
2.11.0
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