From: Qiaobin Fu <qiaobinf@bu.edu> To: bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com Cc: dev@dpdk.org, doucette@bu.edu, keith.wiles@intel.com, sameh.gobriel@intel.com, charlie.tai@intel.com, stephen@networkplumber.org, nd@arm.com, honnappa.nagarahalli@arm.com, yipeng1.wang@intel.com, michel@digirati.com.br, qiaobinf@bu.edu Subject: [dpdk-dev] [PATCH v4 1/2] hash table: fix a bug in rte_hash_iterate() Date: Tue, 9 Oct 2018 19:29:06 +0000 Message-ID: <20181009192907.85650-1-qiaobinf@bu.edu> (raw) In-Reply-To: <20180831165101.20026-1-qiaobinf@bu.edu> In current implementation of rte_hash_iterate(), it tries to obtain the lock after the while loop. However, this may lead to a bug. Notice the following racing condition: 1. The while loop above finishes because it finds a not empty slot. But it does so without a lock. 2. Then we get the lock. 3. The position that was once not empty is now empty. BUG because next_key is invalid. This patch fixes this small bug. Signed-off-by: Qiaobin Fu <qiaobinf@bu.edu> Reviewed-by: Michel Machado <michel@digirati.com.br> --- lib/librte_hash/rte_cuckoo_hash.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c index f7b86c8c9..a3e76684d 100644 --- a/lib/librte_hash/rte_cuckoo_hash.c +++ b/lib/librte_hash/rte_cuckoo_hash.c @@ -1317,16 +1317,18 @@ rte_hash_iterate(const struct rte_hash *h, const void **key, void **data, uint32 bucket_idx = *next / RTE_HASH_BUCKET_ENTRIES; idx = *next % RTE_HASH_BUCKET_ENTRIES; + __hash_rw_reader_lock(h); /* If current position is empty, go to the next one */ while (h->buckets[bucket_idx].key_idx[idx] == EMPTY_SLOT) { (*next)++; /* End of table */ - if (*next == total_entries) + if (*next == total_entries) { + __hash_rw_reader_unlock(h); return -ENOENT; + } bucket_idx = *next / RTE_HASH_BUCKET_ENTRIES; idx = *next % RTE_HASH_BUCKET_ENTRIES; } - __hash_rw_reader_lock(h); /* Get position of entry in key table */ position = h->buckets[bucket_idx].key_idx[idx]; next_key = (struct rte_hash_key *) ((char *)h->key_store + -- 2.17.1
next prev parent reply other threads:[~2018-10-09 19:30 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-08-31 16:51 [dpdk-dev] [PATCH v3] hash table: add an iterator over conflicting entries Qiaobin Fu 2018-08-31 22:53 ` Gaëtan Rivet 2018-09-04 18:46 ` Michel Machado 2018-09-02 22:05 ` Honnappa Nagarahalli 2018-09-04 19:36 ` Michel Machado 2018-09-05 22:13 ` Honnappa Nagarahalli 2018-09-06 14:28 ` Michel Machado 2018-09-12 20:37 ` Honnappa Nagarahalli 2018-09-20 19:50 ` Michel Machado 2018-09-04 18:55 ` Wang, Yipeng1 2018-09-04 19:07 ` Michel Machado 2018-09-04 19:51 ` Wang, Yipeng1 2018-09-04 20:26 ` Michel Machado 2018-09-04 20:57 ` Wang, Yipeng1 2018-09-05 17:52 ` Michel Machado 2018-09-05 20:27 ` Wang, Yipeng1 2018-09-06 13:34 ` Michel Machado 2018-10-09 19:29 ` Qiaobin Fu [this message] 2018-10-09 19:29 ` [dpdk-dev] [PATCH v4 2/2] " Qiaobin Fu 2018-10-10 2:54 ` Wang, Yipeng1 2018-10-10 1:55 ` [dpdk-dev] [PATCH v4 1/2] hash table: fix a bug in rte_hash_iterate() Wang, Yipeng1
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