net/mlx5e: Fix no rewrite fields with the same match

With commit 27c11b6 ("net/mlx5e: Do not rewrite fields with the
same match") there are no rewrites if the rewrite value is the same as
the matched value. However, if the field is not matched, the rewrite is
also wrongly skipped. Fix it.

Fixes: 27c11b6 ("net/mlx5e: Do not rewrite fields with the same match")
Signed-off-by: Eli Britstein <elibr@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -1916,23 +1916,33 @@ struct mlx5_fields {
 		 offsetof(struct pedit_headers, field) + (off), \
 		 MLX5_BYTE_OFF(fte_match_set_lyr_2_4, match_field)}
 
+/* masked values are the same and there are no rewrites that do not have a
+ * match.
+ */
+#define SAME_VAL_MASK(type, valp, maskp, matchvalp, matchmaskp) ({ \
+	type matchmaskx = *(type *)(matchmaskp); \
+	type matchvalx = *(type *)(matchvalp); \
+	type maskx = *(type *)(maskp); \
+	type valx = *(type *)(valp); \
+	\
+	(valx & maskx) == (matchvalx & matchmaskx) && !(maskx & (maskx ^ \
+								 matchmaskx)); \
+})
+
 static bool cmp_val_mask(void *valp, void *maskp, void *matchvalp,
 			 void *matchmaskp, int size)
 {
 	bool same = false;
 
 	switch (size) {
 	case sizeof(u8):
-		same = ((*(u8 *)valp) & (*(u8 *)maskp)) ==
-		       ((*(u8 *)matchvalp) & (*(u8 *)matchmaskp));
+		same = SAME_VAL_MASK(u8, valp, maskp, matchvalp, matchmaskp);
 		break;
 	case sizeof(u16):
-		same = ((*(u16 *)valp) & (*(u16 *)maskp)) ==
-		       ((*(u16 *)matchvalp) & (*(u16 *)matchmaskp));
+		same = SAME_VAL_MASK(u16, valp, maskp, matchvalp, matchmaskp);
 		break;
 	case sizeof(u32):
-		same = ((*(u32 *)valp) & (*(u32 *)maskp)) ==
-		       ((*(u32 *)matchvalp) & (*(u32 *)matchmaskp));
+		same = SAME_VAL_MASK(u32, valp, maskp, matchvalp, matchmaskp);
 		break;
 	}