[dpdk-dev] [PATCH] lib/librte_hash: add rte_hash_del_key_fixed without compact

["Lilijun (Jerry)" <jerry.lilijun@huawei.com>]

The keys idx are stored in rte_hash main bucket key slots and extend bucket key stots. 
We iterate every no empty Keys in h->buckets and h->buckets_ext from start to last. 
When deleting keys the function __rte_hash_compact_ll() may move last_bkt's key to previous bucket in order to compact extend bucket list.
If the previous bucket has been iterated, the moved key may be missed for users. 
Then those missed keys are leaked and rte_hash table can't be cleanup.
So we add a new API rte_hash_del_key_fixed() used in iterate loop to avoid this bugs.

---
 lib/librte_hash/rte_cuckoo_hash.c    | 19 ++++++++++++++-----
 lib/librte_hash/rte_hash.h           |  5 +++++
 lib/librte_hash/rte_hash_version.map |  1 +
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index b52630b..2da3c1d 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1523,7 +1523,7 @@ search_and_remove(const struct rte_hash *h, const void *key,
 
 static inline int32_t
 __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
-						hash_sig_t sig)
+						hash_sig_t sig, uint8_t compact)
 {
 	uint32_t prim_bucket_idx, sec_bucket_idx;
 	struct rte_hash_bucket *prim_bkt, *sec_bkt, *prev_bkt, *last_bkt;
@@ -1541,7 +1541,8 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
 	/* look for key in primary bucket */
 	ret = search_and_remove(h, key, prim_bkt, short_sig, &pos);
 	if (ret != -1) {
-		__rte_hash_compact_ll(h, prim_bkt, pos);
+		if (compact)
+			__rte_hash_compact_ll(h, prim_bkt, pos);
 		last_bkt = prim_bkt->next;
 		prev_bkt = prim_bkt;
 		goto return_bkt;
@@ -1553,7 +1554,8 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
 	FOR_EACH_BUCKET(cur_bkt, sec_bkt) {
 		ret = search_and_remove(h, key, cur_bkt, short_sig, &pos);
 		if (ret != -1) {
-			__rte_hash_compact_ll(h, cur_bkt, pos);
+			if (compact)
+				__rte_hash_compact_ll(h, cur_bkt, pos);
 			last_bkt = sec_bkt->next;
 			prev_bkt = sec_bkt;
 			goto return_bkt;
@@ -1607,14 +1609,21 @@ rte_hash_del_key_with_hash(const struct rte_hash *h,
 			const void *key, hash_sig_t sig)
 {
 	RETURN_IF_TRUE(((h == NULL) || (key == NULL)), -EINVAL);
-	return __rte_hash_del_key_with_hash(h, key, sig);
+	return __rte_hash_del_key_with_hash(h, key, sig, 1);
 }
 
 int32_t
 rte_hash_del_key(const struct rte_hash *h, const void *key)
 {
 	RETURN_IF_TRUE(((h == NULL) || (key == NULL)), -EINVAL);
-	return __rte_hash_del_key_with_hash(h, key, rte_hash_hash(h, key));
+	return __rte_hash_del_key_with_hash(h, key, rte_hash_hash(h, key), 1);
+}
+
+int32_t
+rte_hash_del_key_fixed(const struct rte_hash *h, const void *key)
+{
+	RETURN_IF_TRUE(((h == NULL) || (key == NULL)), -EINVAL);
+	return __rte_hash_del_key_with_hash(h, key, rte_hash_hash(h, key), 0);
 }
 
 int
diff --git a/lib/librte_hash/rte_hash.h b/lib/librte_hash/rte_hash.h
index eceb365..9b71d8a 100644
--- a/lib/librte_hash/rte_hash.h
+++ b/lib/librte_hash/rte_hash.h
@@ -297,6 +297,11 @@ rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key, hash_sig_t
 int32_t
 rte_hash_del_key(const struct rte_hash *h, const void *key);
 
+
+/* for without compact */
+int32_t
+rte_hash_del_key_fixed(const struct rte_hash *h, const void *key);
+
 /**
  * Remove a key from an existing hash table.
  * This operation is not multi-thread safe
diff --git a/lib/librte_hash/rte_hash_version.map b/lib/librte_hash/rte_hash_version.map
index 30cc086..1941d17 100644
--- a/lib/librte_hash/rte_hash_version.map
+++ b/lib/librte_hash/rte_hash_version.map
@@ -11,6 +11,7 @@ DPDK_20.0 {
 	rte_hash_count;
 	rte_hash_create;
 	rte_hash_del_key;
+	rte_hash_del_key_fixed;
 	rte_hash_del_key_with_hash;
 	rte_hash_find_existing;
 	rte_hash_free;
-- 
2.19.1

-----邮件原件-----
发件人: Lilijun (Jerry) 
发送时间: 2020年4月18日 18:00
收件人: 'dev@dpdk.org' <dev@dpdk.org>; 'stable@dpdk.org' <stable@dpdk.org>
主题: rte_hash bug: can't iterate all entries when deleting keys in rte_hash iterate loop.

Hi all,

    In my test, entries can't be cleanup in rte_hash table when deleting keys in rte_hash iterate loop. The test steps:
    1.  create a hash table table1 with limit 30000, ext bucket enabled,  and insert 30000 entries into this hash table.
    2.  create a larger hash table table2 with limit 60000, , ext bucket enabled.
    3.  iterate all entries of table1 and insert them to the table2. Insert new 10000 entries to this table2.
    4.  Then flush all entries from table2 by deleting keys in rte_hash iterate loop. But there are still some keys leaked in table2.

    From my analysis, the keys idx are stored in rte_hash main bucket key slots and extend bucket key stots. 
    We iterate every no empty Keys in h->buckets and h->buckets_ext from start to last. 
    When deleting keys the function __rte_hash_compact_ll() may move last_bkt's key to previous bucket in order to compact extend bucket list.
    If the previous bucket has been iterated, the moved key may be missed for users. 
    Then those missed keys are leaked and rte_hash table can't be cleanup.

    Now I retry the iterate and delete keys, that can avoid this bug. 

    Is there any ideas or solutions on this bug?   Thanks.

Jerry.