ice: switch: add and use u16[] aliases to ice_adv_lkup_elem::{h, m}_u

ice_adv_lkup_elem fields h_u and m_u are being accessed as raw u16
arrays in several places.
To reduce cast and braces burden, add permanent array-of-u16 aliases
with the same size as the `union ice_prot_hdr` itself via anonymous
unions to the actual struct declaration, and just access them
directly.

This:
 - removes the need to cast the union to u16[] and then dereference
   it each time -> reduces the horizon for potential bugs;
 - improves -Warray-bounds coverage -- the array size is now known
   at compilation time;
 - addresses cppcheck complaints.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_switch.c

@@ -5811,12 +5811,12 @@ ice_fill_adv_dummy_packet(struct ice_adv_lkup_elem *lkups, u16 lkups_cnt,
 		 * over any significant packet data.
 		 */
 		for (j = 0; j < len / sizeof(u16); j++)
-			if (((u16 *)&lkups[i].m_u)[j])
+			if (lkups[i].m_raw[j])
 				((u16 *)(pkt + offset))[j] =
 					(((u16 *)(pkt + offset))[j] &
-					 ~((u16 *)&lkups[i].m_u)[j]) |
-					(((u16 *)&lkups[i].h_u)[j] &
-					 ((u16 *)&lkups[i].m_u)[j]);
+					 ~lkups[i].m_raw[j]) |
+					(lkups[i].h_raw[j] &
+					 lkups[i].m_raw[j]);
 	}
 
 	s_rule->pdata.lkup_tx_rx.hdr_len = cpu_to_le16(pkt_len);
@@ -6065,11 +6065,10 @@ ice_add_adv_rule(struct ice_hw *hw, struct ice_adv_lkup_elem *lkups,
 	/* get # of words we need to match */
 	word_cnt = 0;
 	for (i = 0; i < lkups_cnt; i++) {
-		u16 j, *ptr;
+		u16 j;
 
-		ptr = (u16 *)&lkups[i].m_u;
-		for (j = 0; j < sizeof(lkups->m_u) / sizeof(u16); j++)
-			if (ptr[j] != 0)
+		for (j = 0; j < ARRAY_SIZE(lkups->m_raw); j++)
+			if (lkups[i].m_raw[j])
 				word_cnt++;
 	}
 

drivers/net/ethernet/intel/ice/ice_switch.h

@@ -138,8 +138,16 @@ struct ice_update_recipe_lkup_idx_params {
 
 struct ice_adv_lkup_elem {
 	enum ice_protocol_type type;
-	union ice_prot_hdr h_u;	/* Header values */
-	union ice_prot_hdr m_u;	/* Mask of header values to match */
+	union {
+		union ice_prot_hdr h_u;	/* Header values */
+		/* Used to iterate over the headers */
+		u16 h_raw[sizeof(union ice_prot_hdr) / sizeof(u16)];
+	};
+	union {
+		union ice_prot_hdr m_u;	/* Mask of header values to match */
+		/* Used to iterate over header mask */
+		u16 m_raw[sizeof(union ice_prot_hdr) / sizeof(u16)];
+	};
 };
 
 struct ice_sw_act_ctrl {