[PATCH v2] net/mlx5e: Refactor switch statements to avoid using uninitialized variables

From: Nathan Chancellor
Date: Wed Jul 10 2019 - 00:53:59 EST


clang warns:

drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c:251:2:
warning: variable 'rec_seq_sz' is used uninitialized whenever switch
default is taken [-Wsometimes-uninitialized]
default:
^~~~~~~
drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c:255:46: note:
uninitialized use occurs here
skip_static_post = !memcmp(rec_seq, &rn_be, rec_seq_sz);
^~~~~~~~~~
drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c:239:16: note:
initialize the variable 'rec_seq_sz' to silence this warning
u16 rec_seq_sz;
^
= 0
1 warning generated.

The default case statement should return in tx_post_resync_params like
in fill_static_params_ctx. However, as Nick and Leon point out, the
switch statements converted into if statements to clean up the code a
bit since there is only one cipher supported. Do that to clear up the
code.

Fixes: d2ead1f360e8 ("net/mlx5e: Add kTLS TX HW offload support")
Link: https://github.com/ClangBuiltLinux/linux/issues/590
Suggested-by: Leon Romanovsky <leon@xxxxxxxxxx>
Suggested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---

v1 -> v2:

* Refactor switch statements into if statements

.../mellanox/mlx5/core/en_accel/ktls_tx.c | 33 +++++++------------
1 file changed, 11 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
index 3f5f4317a22b..ea032f54197e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
@@ -25,23 +25,17 @@ static void
fill_static_params_ctx(void *ctx, struct mlx5e_ktls_offload_context_tx *priv_tx)
{
struct tls_crypto_info *crypto_info = priv_tx->crypto_info;
+ struct tls12_crypto_info_aes_gcm_128 *info;
char *initial_rn, *gcm_iv;
u16 salt_sz, rec_seq_sz;
char *salt, *rec_seq;
u8 tls_version;

- switch (crypto_info->cipher_type) {
- case TLS_CIPHER_AES_GCM_128: {
- struct tls12_crypto_info_aes_gcm_128 *info =
- (struct tls12_crypto_info_aes_gcm_128 *)crypto_info;
-
- EXTRACT_INFO_FIELDS;
- break;
- }
- default:
- WARN_ON(1);
+ if (WARN_ON(crypto_info->cipher_type != TLS_CIPHER_AES_GCM_128))
return;
- }
+
+ info = (struct tls12_crypto_info_aes_gcm_128 *)crypto_info;
+ EXTRACT_INFO_FIELDS;

gcm_iv = MLX5_ADDR_OF(tls_static_params, ctx, gcm_iv);
initial_rn = MLX5_ADDR_OF(tls_static_params, ctx, initial_record_number);
@@ -234,23 +228,18 @@ tx_post_resync_params(struct mlx5e_txqsq *sq,
u64 rcd_sn)
{
struct tls_crypto_info *crypto_info = priv_tx->crypto_info;
+ struct tls12_crypto_info_aes_gcm_128 *info;
__be64 rn_be = cpu_to_be64(rcd_sn);
bool skip_static_post;
u16 rec_seq_sz;
char *rec_seq;

- switch (crypto_info->cipher_type) {
- case TLS_CIPHER_AES_GCM_128: {
- struct tls12_crypto_info_aes_gcm_128 *info =
- (struct tls12_crypto_info_aes_gcm_128 *)crypto_info;
+ if (WARN_ON(crypto_info->cipher_type != TLS_CIPHER_AES_GCM_128))
+ return;

- rec_seq = info->rec_seq;
- rec_seq_sz = sizeof(info->rec_seq);
- break;
- }
- default:
- WARN_ON(1);
- }
+ info = (struct tls12_crypto_info_aes_gcm_128 *)crypto_info;
+ rec_seq = info->rec_seq;
+ rec_seq_sz = sizeof(info->rec_seq);

skip_static_post = !memcmp(rec_seq, &rn_be, rec_seq_sz);
if (!skip_static_post)
--
2.22.0