Hi Andre,

From: Konstantin Ananyev <konstantin.ananyev@huawei.com>

1) ./lib/hash/rte_thash.c:774:9
    : warning: ISO C90 forbids variable length array ‘tmp_tuple’

From my understanding, tuple size here should never exceed
sizeof(union rte_thash_tuple), so it should be safe to replace VLA with
fixed size array.

The tuple can exceed this size, for example if you use any tunneling header in RSS hash calculation.

Here I suggest using as a limit the size of the longest RSS hash key currently supported, which is 52 bytes. Technically, the longest tuple with such a key should be (52 - sizeof(uint32_t)), so you can use this as a size of the tmp_tuple array

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
---
 lib/hash/rte_thash.c | 2 +-
 lib/hash/rte_thash.h | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/hash/rte_thash.c b/lib/hash/rte_thash.c
index 336c228e64..842e3ad85d 100644
--- a/lib/hash/rte_thash.c
+++ b/lib/hash/rte_thash.c
@@ -761,7 +761,7 @@ rte_thash_adjust_tuple(struct rte_thash_ctx *ctx,
 	uint32_t desired_value,	unsigned int attempts,
 	rte_thash_check_tuple_t fn, void *userdata)
 {
-	uint32_t tmp_tuple[tuple_len / sizeof(uint32_t)];
+	uint32_t tmp_tuple[RTE_THASH_MAX_L4_LEN];
 	unsigned int i, j, ret = 0;
 	uint32_t hash, adj_bits;
 	const uint8_t *hash_key;
diff --git a/lib/hash/rte_thash.h b/lib/hash/rte_thash.h
index c0af5968df..427246ad2e 100644
--- a/lib/hash/rte_thash.h
+++ b/lib/hash/rte_thash.h
@@ -121,6 +121,14 @@ __rte_internal
 uint32_t
 thash_get_rand_poly(uint32_t poly_degree);
 
+/**
+ * maximum length in dwords of input tuple to
+ * calculate hash of ipv(4|6) header +
+ * transport header
+ */
+#define RTE_THASH_MAX_L4_LEN	\
+	((sizeof(union rte_thash_tuple)) / sizeof(uint32_t))
+
 /**
  * Prepare special converted key to use with rte_softrss_be()
  * @param orig

-- 
Regards,
Vladimir