[dpdk-dev] [PATCH] hash: fix gcc 10 maybe-uninitialized warning

[Kevin Traynor <ktraynor@redhat.com>]

gcc 10.1.1 reports a warning for the ext_bkt_id variable:

../lib/librte_hash/rte_cuckoo_hash.c:
In function ‘__rte_hash_add_key_with_hash’:
../lib/librte_hash/rte_cuckoo_hash.c:1104:29:
warning: ‘ext_bkt_id’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
 1104 |  (h->buckets_ext[ext_bkt_id - 1]).sig_current[0] = short_sig;
      |                  ~~~~~~~~~~~^~~

The return value of rte_ring_sc_dequeue_elem() is already checked,
but also initialize ext_bkt_id to zero (invalid value) and check
that it also overwritten.

Fixes: fbfe568103b0 ("hash: use 32-bit elements rings to save memory")
Cc: stable@dpdk.org

Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 38767a8a1..90cb99b0e 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -940,6 +940,6 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 	struct rte_hash_bucket *prim_bkt, *sec_bkt, *cur_bkt;
 	struct rte_hash_key *new_k, *keys = h->key_store;
+	uint32_t ext_bkt_id = 0;
 	uint32_t slot_id;
-	uint32_t ext_bkt_id;
 	int ret;
 	unsigned n_slots;
@@ -1096,5 +1096,6 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 	 */
 	if (rte_ring_sc_dequeue_elem(h->free_ext_bkts, &ext_bkt_id,
-						sizeof(uint32_t)) != 0) {
+						sizeof(uint32_t)) != 0 ||
+					ext_bkt_id == 0) {
 		ret = -ENOSPC;
 		goto failure;
-- 
2.21.3