This patch modifies __rhashtable_insert_fast() so it returns the
existing element that clashes with the one that you want to insert.
This adds a new rhashtable_lookup_get_insert_key() interface to fetch
this existing element.
nf_tables needs this change to improve handling of EEXIST cases via
honoring the NLM_F_EXCL flag and by checking if the data part of the
mapping matches what we have.
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Thomas Graf <tgraf@xxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/linux/rhashtable.h | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 3eef080..a632cf0 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -566,7 +566,7 @@ restart:
/* Internal function, please use rhashtable_insert_fast() instead */
static inline int __rhashtable_insert_fast(
struct rhashtable *ht, const void *key, struct rhash_head *obj,
- const struct rhashtable_params params)
+ const struct rhashtable_params params, void **data)
{
struct rhashtable_compare_arg arg = {
.ht = ht,
@@ -630,8 +630,11 @@ slow_path:
if (key &&
unlikely(!(params.obj_cmpfn ?
params.obj_cmpfn(&arg, rht_obj(ht, head)) :
- rhashtable_compare(&arg, rht_obj(ht, head)))))
+ rhashtable_compare(&arg, rht_obj(ht, head))))) {
+ if (data)
+ *data = rht_obj(ht, head);
goto out;
+ }
if (!--elasticity)
goto slow_path;
}
@@ -675,7 +678,7 @@ static inline int rhashtable_insert_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
{
- return __rhashtable_insert_fast(ht, NULL, obj, params);
+ return __rhashtable_insert_fast(ht, NULL, obj, params, NULL);
}
/**
@@ -708,7 +711,7 @@ static inline int rhashtable_lookup_insert_fast(
BUG_ON(ht->p.obj_hashfn);
return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj,
- params);
+ params, NULL);
}
/**
@@ -739,7 +742,26 @@ static inline int rhashtable_lookup_insert_key(
{
BUG_ON(!ht->p.obj_hashfn || !key);
- return __rhashtable_insert_fast(ht, key, obj, params);
+ return __rhashtable_insert_fast(ht, key, obj, params, NULL);
+}
+
+/**
+ * rhashtable_lookup_get_insert_key - lookup and insert object into hash table
+ * @ht: hash table
+ * @obj: pointer to hash head inside object
+ * @params: hash table parameters
+ * @data: pointer to element data already in hashes
+ *
+ * Just like rhashtable_lookup_insert_key(), but it returns the matching
+ * element in case that it already exists in the hashes.
+ */
+static inline int rhashtable_lookup_get_insert_key(
+ struct rhashtable *ht, const void *key, struct rhash_head *obj,
+ const struct rhashtable_params params, void **data)
+{
+ BUG_ON(!ht->p.obj_hashfn || !key);
+
+ return __rhashtable_insert_fast(ht, key, obj, params, data);
}
/* Internal function, please use rhashtable_remove_fast() instead */
--
2.1.4
--
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