wifi: mac80211: limit A-MSDU subframes for client too

In AP/mesh where the stations are added by userspace, we
limit the number of A-MSDU subframes according to the
extended capabilities.

Refactor the code and extend that also to client-side.

Fixes: 506bcfa8 ("mac80211: limit the A-MSDU Tx based on peer's capabilities")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -1776,33 +1776,8 @@ static int sta_apply_parameters(struct ieee80211_local *local,
 		sta->sta.max_sp = params->max_sp;
 	}
 
-	/* The sender might not have sent the last bit, consider it to be 0 */
-	if (params->ext_capab_len >= 8) {
-		u8 val = (params->ext_capab[7] &
-			  WLAN_EXT_CAPA8_MAX_MSDU_IN_AMSDU_LSB) >> 7;
-
-		/* we did get all the bits, take the MSB as well */
-		if (params->ext_capab_len >= 9) {
-			u8 val_msb = params->ext_capab[8] &
-				WLAN_EXT_CAPA9_MAX_MSDU_IN_AMSDU_MSB;
-			val_msb <<= 1;
-			val |= val_msb;
-		}
-
-		switch (val) {
-		case 1:
-			sta->sta.max_amsdu_subframes = 32;
-			break;
-		case 2:
-			sta->sta.max_amsdu_subframes = 16;
-			break;
-		case 3:
-			sta->sta.max_amsdu_subframes = 8;
-			break;
-		default:
-			sta->sta.max_amsdu_subframes = 0;
-		}
-	}
+	ieee80211_sta_set_max_amsdu_subframes(sta, params->ext_capab,
+					      params->ext_capab_len);
 
 	/*
 	 * cfg80211 validates this (1-2007) and allows setting the AID

net/mac80211/mlme.c

@@ -4488,6 +4488,9 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 		sta->sta.mfp = false;
 	}
 
+	ieee80211_sta_set_max_amsdu_subframes(sta, elems->ext_capab,
+					      elems->ext_capab_len);
+
 	sta->sta.wme = (elems->wmm_param || elems->s1g_capab) &&
 		       local->hw.queues >= IEEE80211_NUM_ACS;
 

net/mac80211/sta_info.c

@@ -2761,3 +2761,26 @@ void ieee80211_sta_remove_link(struct sta_info *sta, unsigned int link_id)
 
 	sta_remove_link(sta, link_id, true);
 }
+
+void ieee80211_sta_set_max_amsdu_subframes(struct sta_info *sta,
+					   const u8 *ext_capab,
+					   unsigned int ext_capab_len)
+{
+	u8 val;
+
+	sta->sta.max_amsdu_subframes = 0;
+
+	if (ext_capab_len < 8)
+		return;
+
+	/* The sender might not have sent the last bit, consider it to be 0 */
+	val = u8_get_bits(ext_capab[7], WLAN_EXT_CAPA8_MAX_MSDU_IN_AMSDU_LSB);
+
+	/* we did get all the bits, take the MSB as well */
+	if (ext_capab_len >= 9)
+		val |= u8_get_bits(ext_capab[8],
+				   WLAN_EXT_CAPA9_MAX_MSDU_IN_AMSDU_MSB) << 1;
+
+	if (val)
+		sta->sta.max_amsdu_subframes = 4 << val;
+}

net/mac80211/sta_info.h

@@ -910,6 +910,10 @@ void ieee80211_sta_ps_deliver_uapsd(struct sta_info *sta);
 
 unsigned long ieee80211_sta_last_active(struct sta_info *sta);
 
+void ieee80211_sta_set_max_amsdu_subframes(struct sta_info *sta,
+					   const u8 *ext_capab,
+					   unsigned int ext_capab_len);
+
 enum sta_stats_type {
 	STA_STATS_RATE_TYPE_INVALID = 0,
 	STA_STATS_RATE_TYPE_LEGACY,