[dpdk-dev] [PATCH] net/mlx4: fix undefined behavior of RSS conversion

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

As reported by ICC, an array initializer that uses values found in the
array being initialized, although semantically correct (GCC and clang do
not complain and generate correct code), results in undefined behavior
since initialization order is itself undefined.

This patch restores the static keyword and initializes array entries with
constant expressions as a safety measure.

Fixes: f76ccd763422 ("net/mlx4: refactor RSS conversion functions")

Reported-by: Ferruh Yigit <ferruh.yigit@intel.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

--

Shahaf, Ferruh, please remove the "Note the loss of the [...]" paragraph of
the original commit if this patch gets squashed in it, as it is no longer
relevant in that case.
---
 drivers/net/mlx4/mlx4_flow.c | 38 ++++++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/drivers/net/mlx4/mlx4_flow.c b/drivers/net/mlx4/mlx4_flow.c
index ddb7108dc..b40e7e5c3 100644
--- a/drivers/net/mlx4/mlx4_flow.c
+++ b/drivers/net/mlx4/mlx4_flow.c
@@ -103,6 +103,12 @@ mlx4_conv_rss_types(struct priv *priv, uint64_t types, int verbs_to_dpdk)
 		TCP, UDP,
 		IPV4_TCP, IPV4_UDP, IPV6_TCP, IPV6_TCP_1, IPV6_UDP, IPV6_UDP_1,
 	};
+	enum {
+		VERBS_IPV4 = IBV_RX_HASH_SRC_IPV4 | IBV_RX_HASH_DST_IPV4,
+		VERBS_IPV6 = IBV_RX_HASH_SRC_IPV6 | IBV_RX_HASH_DST_IPV6,
+		VERBS_TCP = IBV_RX_HASH_SRC_PORT_TCP | IBV_RX_HASH_DST_PORT_TCP,
+		VERBS_UDP = IBV_RX_HASH_SRC_PORT_UDP | IBV_RX_HASH_DST_PORT_UDP,
+	};
 	static const uint64_t dpdk[] = {
 		[INNER] = 0,
 		[IPV4] = ETH_RSS_IPV4,
@@ -121,23 +127,23 @@ mlx4_conv_rss_types(struct priv *priv, uint64_t types, int verbs_to_dpdk)
 		[IPV6_UDP] = ETH_RSS_NONFRAG_IPV6_UDP,
 		[IPV6_UDP_1] = ETH_RSS_IPV6_UDP_EX,
 	};
-	const uint64_t verbs[RTE_DIM(dpdk)] = {
+	static const uint64_t verbs[RTE_DIM(dpdk)] = {
 		[INNER] = IBV_RX_HASH_INNER,
-		[IPV4] = IBV_RX_HASH_SRC_IPV4 | IBV_RX_HASH_DST_IPV4,
-		[IPV4_1] = verbs[IPV4],
-		[IPV4_2] = verbs[IPV4],
-		[IPV6] = IBV_RX_HASH_SRC_IPV6 | IBV_RX_HASH_DST_IPV6,
-		[IPV6_1] = verbs[IPV6],
-		[IPV6_2] = verbs[IPV6],
-		[IPV6_3] = verbs[IPV6],
-		[TCP] = IBV_RX_HASH_SRC_PORT_TCP | IBV_RX_HASH_DST_PORT_TCP,
-		[UDP] = IBV_RX_HASH_SRC_PORT_UDP | IBV_RX_HASH_DST_PORT_UDP,
-		[IPV4_TCP] = verbs[IPV4] | verbs[TCP],
-		[IPV4_UDP] = verbs[IPV4] | verbs[UDP],
-		[IPV6_TCP] = verbs[IPV6] | verbs[TCP],
-		[IPV6_TCP_1] = verbs[IPV6_TCP],
-		[IPV6_UDP] = verbs[IPV6] | verbs[UDP],
-		[IPV6_UDP_1] = verbs[IPV6_UDP],
+		[IPV4] = VERBS_IPV4,
+		[IPV4_1] = VERBS_IPV4,
+		[IPV4_2] = VERBS_IPV4,
+		[IPV6] = VERBS_IPV6,
+		[IPV6_1] = VERBS_IPV6,
+		[IPV6_2] = VERBS_IPV6,
+		[IPV6_3] = VERBS_IPV6,
+		[TCP] = VERBS_TCP,
+		[UDP] = VERBS_UDP,
+		[IPV4_TCP] = VERBS_IPV4 | VERBS_TCP,
+		[IPV4_UDP] = VERBS_IPV4 | VERBS_UDP,
+		[IPV6_TCP] = VERBS_IPV6 | VERBS_TCP,
+		[IPV6_TCP_1] = VERBS_IPV6 | VERBS_TCP,
+		[IPV6_UDP] = VERBS_IPV6 | VERBS_UDP,
+		[IPV6_UDP_1] = VERBS_IPV6 | VERBS_UDP,
 	};
 	const uint64_t *in = verbs_to_dpdk ? verbs : dpdk;
 	const uint64_t *out = verbs_to_dpdk ? dpdk : verbs;
-- 
2.11.0