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-rw-r--r--lib/rhashtable.c51
1 files changed, 46 insertions, 5 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 2b2b79974b61..9427b5766134 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -668,8 +668,9 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
* For a completely stable walk you should construct your own data
* structure outside the hash table.
*
- * This function may sleep so you must not call it from interrupt
- * context or with spin locks held.
+ * This function may be called from any process context, including
+ * non-preemptable context, but cannot be called from softirq or
+ * hardirq context.
*
* You must call rhashtable_walk_exit after this function returns.
*/
@@ -726,6 +727,7 @@ int rhashtable_walk_start_check(struct rhashtable_iter *iter)
__acquires(RCU)
{
struct rhashtable *ht = iter->ht;
+ bool rhlist = ht->rhlist;
rcu_read_lock();
@@ -734,11 +736,52 @@ int rhashtable_walk_start_check(struct rhashtable_iter *iter)
list_del(&iter->walker.list);
spin_unlock(&ht->lock);
- if (!iter->walker.tbl && !iter->end_of_table) {
+ if (iter->end_of_table)
+ return 0;
+ if (!iter->walker.tbl) {
iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht);
+ iter->slot = 0;
+ iter->skip = 0;
return -EAGAIN;
}
+ if (iter->p && !rhlist) {
+ /*
+ * We need to validate that 'p' is still in the table, and
+ * if so, update 'skip'
+ */
+ struct rhash_head *p;
+ int skip = 0;
+ rht_for_each_rcu(p, iter->walker.tbl, iter->slot) {
+ skip++;
+ if (p == iter->p) {
+ iter->skip = skip;
+ goto found;
+ }
+ }
+ iter->p = NULL;
+ } else if (iter->p && rhlist) {
+ /* Need to validate that 'list' is still in the table, and
+ * if so, update 'skip' and 'p'.
+ */
+ struct rhash_head *p;
+ struct rhlist_head *list;
+ int skip = 0;
+ rht_for_each_rcu(p, iter->walker.tbl, iter->slot) {
+ for (list = container_of(p, struct rhlist_head, rhead);
+ list;
+ list = rcu_dereference(list->next)) {
+ skip++;
+ if (list == iter->list) {
+ iter->p = p;
+ skip = skip;
+ goto found;
+ }
+ }
+ }
+ iter->p = NULL;
+ }
+found:
return 0;
}
EXPORT_SYMBOL_GPL(rhashtable_walk_start_check);
@@ -914,8 +957,6 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
iter->walker.tbl = NULL;
spin_unlock(&ht->lock);
- iter->p = NULL;
-
out:
rcu_read_unlock();
}