From: Yipeng Wang Date: Tue, 10 Jul 2018 16:59:55 +0000 (-0700) Subject: hash: fix a multi-writer race condition X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=eb067d431d9411a0054bc3ec084b0e9eadbb0a16;p=dpdk.git hash: fix a multi-writer race condition Current multi-writer implementation uses Intel TSX to protect the cuckoo path moving but not the cuckoo path searching. After searching, we need to verify again if the same empty slot still exists at the beginning of the TSX region. Otherwise another writer could occupy the empty slot before the TSX region. Current code does not verify. Fixes: be856325cba3 ("hash: add scalable multi-writer insertion with Intel TSX") Cc: stable@dpdk.org Signed-off-by: Yipeng Wang Acked-by: Pablo de Lara --- diff --git a/lib/librte_hash/rte_cuckoo_hash_x86.h b/lib/librte_hash/rte_cuckoo_hash_x86.h index 2c5b017e36..981d7bdd60 100644 --- a/lib/librte_hash/rte_cuckoo_hash_x86.h +++ b/lib/librte_hash/rte_cuckoo_hash_x86.h @@ -66,6 +66,9 @@ rte_hash_cuckoo_move_insert_mw_tm(const struct rte_hash *h, while (try < RTE_HASH_TSX_MAX_RETRY) { status = rte_xbegin(); if (likely(status == RTE_XBEGIN_STARTED)) { + /* In case empty slot was gone before entering TSX */ + if (curr_bkt->key_idx[curr_slot] != EMPTY_SLOT) + rte_xabort(RTE_XABORT_CUCKOO_PATH_INVALIDED); while (likely(curr_node->prev != NULL)) { prev_node = curr_node->prev; prev_bkt = prev_node->bkt;