nl80211: move unsplit command advertising to a separate function

When we split the wiphy dump because it got too large, I added a
comment and asked that all new command advertising be done only
for userspace clients capable of receiving split data, in order
to not break older ones (which can't use the new commands anyway)

This mostly worked, and we haven't added many new commands, but
I occasionally get patches that modify the wrong place.

Make this easier to detect and understand by splitting out the
old commands to a separate function that makes it more clear it
should never be modified again.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -1328,6 +1328,95 @@ nl80211_send_mgmt_stypes(struct sk_buff *msg,
 	return 0;
 }
 
+#define CMD(op, n)							\
+	 do {								\
+		if (rdev->ops->op) {					\
+			i++;						\
+			if (nla_put_u32(msg, i, NL80211_CMD_ ## n)) 	\
+				goto nla_put_failure;			\
+		}							\
+	} while (0)
+
+static int nl80211_add_commands_unsplit(struct cfg80211_registered_device *rdev,
+					struct sk_buff *msg)
+{
+	int i = 0;
+
+	/*
+	 * do *NOT* add anything into this function, new things need to be
+	 * advertised only to new versions of userspace that can deal with
+	 * the split (and they can't possibly care about new features...
+	 */
+	CMD(add_virtual_intf, NEW_INTERFACE);
+	CMD(change_virtual_intf, SET_INTERFACE);
+	CMD(add_key, NEW_KEY);
+	CMD(start_ap, START_AP);
+	CMD(add_station, NEW_STATION);
+	CMD(add_mpath, NEW_MPATH);
+	CMD(update_mesh_config, SET_MESH_CONFIG);
+	CMD(change_bss, SET_BSS);
+	CMD(auth, AUTHENTICATE);
+	CMD(assoc, ASSOCIATE);
+	CMD(deauth, DEAUTHENTICATE);
+	CMD(disassoc, DISASSOCIATE);
+	CMD(join_ibss, JOIN_IBSS);
+	CMD(join_mesh, JOIN_MESH);
+	CMD(set_pmksa, SET_PMKSA);
+	CMD(del_pmksa, DEL_PMKSA);
+	CMD(flush_pmksa, FLUSH_PMKSA);
+	if (rdev->wiphy.flags & WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL)
+		CMD(remain_on_channel, REMAIN_ON_CHANNEL);
+	CMD(set_bitrate_mask, SET_TX_BITRATE_MASK);
+	CMD(mgmt_tx, FRAME);
+	CMD(mgmt_tx_cancel_wait, FRAME_WAIT_CANCEL);
+	if (rdev->wiphy.flags & WIPHY_FLAG_NETNS_OK) {
+		i++;
+		if (nla_put_u32(msg, i, NL80211_CMD_SET_WIPHY_NETNS))
+			goto nla_put_failure;
+	}
+	if (rdev->ops->set_monitor_channel || rdev->ops->start_ap ||
+	    rdev->ops->join_mesh) {
+		i++;
+		if (nla_put_u32(msg, i, NL80211_CMD_SET_CHANNEL))
+			goto nla_put_failure;
+	}
+	CMD(set_wds_peer, SET_WDS_PEER);
+	if (rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_TDLS) {
+		CMD(tdls_mgmt, TDLS_MGMT);
+		CMD(tdls_oper, TDLS_OPER);
+	}
+	if (rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN)
+		CMD(sched_scan_start, START_SCHED_SCAN);
+	CMD(probe_client, PROBE_CLIENT);
+	CMD(set_noack_map, SET_NOACK_MAP);
+	if (rdev->wiphy.flags & WIPHY_FLAG_REPORTS_OBSS) {
+		i++;
+		if (nla_put_u32(msg, i, NL80211_CMD_REGISTER_BEACONS))
+			goto nla_put_failure;
+	}
+	CMD(start_p2p_device, START_P2P_DEVICE);
+	CMD(set_mcast_rate, SET_MCAST_RATE);
+#ifdef CONFIG_NL80211_TESTMODE
+	CMD(testmode_cmd, TESTMODE);
+#endif
+
+	if (rdev->ops->connect || rdev->ops->auth) {
+		i++;
+		if (nla_put_u32(msg, i, NL80211_CMD_CONNECT))
+			goto nla_put_failure;
+	}
+
+	if (rdev->ops->disconnect || rdev->ops->deauth) {
+		i++;
+		if (nla_put_u32(msg, i, NL80211_CMD_DISCONNECT))
+			goto nla_put_failure;
+	}
+
+	return i;
+ nla_put_failure:
+	return -ENOBUFS;
+}
+
 struct nl80211_dump_wiphy_state {
 	s64 filter_wiphy;
 	long start;
@@ -1555,68 +1644,9 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev,
 		if (!nl_cmds)
 			goto nla_put_failure;
 
-		i = 0;
-#define CMD(op, n)							\
-		 do {							\
-			if (rdev->ops->op) {				\
-				i++;					\
-				if (nla_put_u32(msg, i, NL80211_CMD_ ## n)) \
-					goto nla_put_failure;		\
-			}						\
-		} while (0)
-
-		CMD(add_virtual_intf, NEW_INTERFACE);
-		CMD(change_virtual_intf, SET_INTERFACE);
-		CMD(add_key, NEW_KEY);
-		CMD(start_ap, START_AP);
-		CMD(add_station, NEW_STATION);
-		CMD(add_mpath, NEW_MPATH);
-		CMD(update_mesh_config, SET_MESH_CONFIG);
-		CMD(change_bss, SET_BSS);
-		CMD(auth, AUTHENTICATE);
-		CMD(assoc, ASSOCIATE);
-		CMD(deauth, DEAUTHENTICATE);
-		CMD(disassoc, DISASSOCIATE);
-		CMD(join_ibss, JOIN_IBSS);
-		CMD(join_mesh, JOIN_MESH);
-		CMD(set_pmksa, SET_PMKSA);
-		CMD(del_pmksa, DEL_PMKSA);
-		CMD(flush_pmksa, FLUSH_PMKSA);
-		if (rdev->wiphy.flags & WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL)
-			CMD(remain_on_channel, REMAIN_ON_CHANNEL);
-		CMD(set_bitrate_mask, SET_TX_BITRATE_MASK);
-		CMD(mgmt_tx, FRAME);
-		CMD(mgmt_tx_cancel_wait, FRAME_WAIT_CANCEL);
-		if (rdev->wiphy.flags & WIPHY_FLAG_NETNS_OK) {
-			i++;
-			if (nla_put_u32(msg, i, NL80211_CMD_SET_WIPHY_NETNS))
-				goto nla_put_failure;
-		}
-		if (rdev->ops->set_monitor_channel || rdev->ops->start_ap ||
-		    rdev->ops->join_mesh) {
-			i++;
-			if (nla_put_u32(msg, i, NL80211_CMD_SET_CHANNEL))
+		i = nl80211_add_commands_unsplit(rdev, msg);
+		if (i < 0)
 			goto nla_put_failure;
-		}
-		CMD(set_wds_peer, SET_WDS_PEER);
-		if (rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_TDLS) {
-			CMD(tdls_mgmt, TDLS_MGMT);
-			CMD(tdls_oper, TDLS_OPER);
-		}
-		if (rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN)
-			CMD(sched_scan_start, START_SCHED_SCAN);
-		CMD(probe_client, PROBE_CLIENT);
-		CMD(set_noack_map, SET_NOACK_MAP);
-		if (rdev->wiphy.flags & WIPHY_FLAG_REPORTS_OBSS) {
-			i++;
-			if (nla_put_u32(msg, i, NL80211_CMD_REGISTER_BEACONS))
-				goto nla_put_failure;
-		}
-		CMD(start_p2p_device, START_P2P_DEVICE);
-		CMD(set_mcast_rate, SET_MCAST_RATE);
-#ifdef CONFIG_NL80211_TESTMODE
-		CMD(testmode_cmd, TESTMODE);
-#endif
 		if (state->split) {
 			CMD(crit_proto_start, CRIT_PROTOCOL_START);
 			CMD(crit_proto_stop, CRIT_PROTOCOL_STOP);
@@ -1627,21 +1657,8 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev,
 					NL80211_FEATURE_SUPPORTS_WMM_ADMISSION)
 				CMD(add_tx_ts, ADD_TX_TS);
 		}
-		/* add into the if now */
 #undef CMD
 
-		if (rdev->ops->connect || rdev->ops->auth) {
-			i++;
-			if (nla_put_u32(msg, i, NL80211_CMD_CONNECT))
-				goto nla_put_failure;
-		}
-
-		if (rdev->ops->disconnect || rdev->ops->deauth) {
-			i++;
-			if (nla_put_u32(msg, i, NL80211_CMD_DISCONNECT))
-				goto nla_put_failure;
-		}
-
 		nla_nest_end(msg, nl_cmds);
 		state->split_start++;
 		if (state->split)