wifi: mac80211: simplify multi-link element parsing

We shouldn't assign elems->ml_basic{,len} before defragmentation,
and we don't need elems->ml_reconf{,len} at all since we don't do
defragmentation. Clean that up a bit. This does require always
defragmention even when it may not be needed, but that's easier
to reason about.
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240228094902.e0115da4d2a6.I89a80f7387eabef8df3955485d4a583ed024c5b1@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -1736,7 +1736,6 @@ struct ieee802_11_elems {
 	const struct ieee80211_eht_cap_elem *eht_cap;
 	const struct ieee80211_eht_operation *eht_operation;
 	const struct ieee80211_multi_link_elem *ml_basic;
-	const struct ieee80211_multi_link_elem *ml_reconf;
 	const struct ieee80211_bandwidth_indication *bandwidth_indication;
 	const struct ieee80211_ttlm_elem *ttlm[IEEE80211_TTLM_MAX_CNT];
 
@@ -1764,12 +1763,11 @@ struct ieee802_11_elems {
 
 	/* mult-link element can be de-fragmented and thus u8 is not sufficient */
 	size_t ml_basic_len;
-	size_t ml_reconf_len;
 
-	/* The basic Multi-Link element in the original IEs */
+	/* The basic Multi-Link element in the original elements */
 	const struct element *ml_basic_elem;
 
-	/* The reconfiguration Multi-Link element in the original IEs */
+	/* The reconfiguration Multi-Link element in the original elements */
 	const struct element *ml_reconf_elem;
 
 	u8 ttlm_num;

net/mac80211/mlme.c

@@ -5760,7 +5760,7 @@ static void ieee80211_ml_reconfiguration(struct ieee80211_sub_if_data *sdata,
 	u8 link_id;
 	u32 delay;
 
-	if (!ieee80211_vif_is_mld(&sdata->vif) || !elems->ml_reconf)
+	if (!ieee80211_vif_is_mld(&sdata->vif) || !elems->ml_reconf_elem)
 		return;
 
 	ml_len = cfg80211_defragment_element(elems->ml_reconf_elem,
@@ -5773,9 +5773,7 @@ static void ieee80211_ml_reconfiguration(struct ieee80211_sub_if_data *sdata,
 	if (ml_len < 0)
 		return;
 
-	elems->ml_reconf = (const void *)elems->scratch_pos;
-	elems->ml_reconf_len = ml_len;
-	ml = elems->ml_reconf;
+	ml = (const void *)elems->scratch_pos;
 
 	/* Directly parse the sub elements as the common information doesn't
 	 * hold any useful information.

net/mac80211/parse.c

@@ -129,19 +129,15 @@ ieee80211_parse_extension_element(u32 *crc,
 			switch (le16_get_bits(mle->control,
 					      IEEE80211_ML_CONTROL_TYPE)) {
 			case IEEE80211_ML_CONTROL_TYPE_BASIC:
-				if (elems->ml_basic) {
+				if (elems->ml_basic_elem) {
 					elems->parse_error |=
 						IEEE80211_PARSE_ERR_DUP_NEST_ML_BASIC;
 					break;
 				}
 				elems->ml_basic_elem = (void *)elem;
-				elems->ml_basic = data;
-				elems->ml_basic_len = len;
 				break;
 			case IEEE80211_ML_CONTROL_TYPE_RECONF:
 				elems->ml_reconf_elem = (void *)elem;
-				elems->ml_reconf = data;
-				elems->ml_reconf_len = len;
 				break;
 			default:
 				break;
@@ -776,9 +772,6 @@ static void ieee80211_mle_parse_link(struct ieee802_11_elems *elems,
 	const struct element *non_inherit = NULL;
 	const u8 *end;
 
-	if (params->link_id == -1)
-		return;
-
 	ml_len = cfg80211_defragment_element(elems->ml_basic_elem,
 					     elems->ie_start,
 					     elems->total_len,
@@ -795,6 +788,9 @@ static void ieee80211_mle_parse_link(struct ieee802_11_elems *elems,
 	elems->ml_basic_len = ml_len;
 	elems->scratch_pos += ml_len;
 
+	if (params->link_id == -1)
+		return;
+
 	ieee80211_mle_get_sta_prof(elems, params->link_id);
 	prof = elems->prof;