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From: "Lilijun (Jerry)" <jerry.lilijun@huawei.com>
To: "'dev@dpdk.org'" <dev@dpdk.org>, "'stable@dpdk.org'" <stable@dpdk.org>
Thread-Topic: rte_hash bug: can't iterate all entries when deleting keys in
 rte_hash iterate loop.
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Date: Sat, 18 Apr 2020 10:00:09 +0000
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Subject: [dpdk-stable] rte_hash bug: can't iterate all entries when deleting
 keys in rte_hash iterate loop.
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Hi all,

    In my test, entries can't be cleanup in rte_hash table when deleting ke=
ys in rte_hash iterate loop. The test steps:
    1.  create a hash table table1 with limit 30000, ext bucket enabled,  a=
nd insert 30000 entries into this hash table.
    2.  create a larger hash table table2 with limit 60000, , ext bucket en=
abled.
    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 ite=
rate loop. But there are still some keys leaked in table2.

    From my analysis, the keys idx are stored in rte_hash main bucket key s=
lots and extend bucket key stots.=20
    We iterate every no empty Keys in h->buckets and h->buckets_ext from st=
art to last.=20
    When deleting keys the function __rte_hash_compact_ll() may move last_b=
kt'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 f=
or users.=20
    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.=20

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

Jerry.