batman-adv: Directly print to seq_file in vis

The vis output doesn't need to be buffered in an character buffer before it can
be send to the userspace program that reads from the vis debug file.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
diff --git a/net/batman-adv/vis.c b/net/batman-adv/vis.c
index 6b7a1c0..3095c41 100644
--- a/net/batman-adv/vis.c
+++ b/net/batman-adv/vis.c
@@ -140,72 +140,117 @@
 	hlist_add_head(&entry->list, if_list);
 }
 
-static ssize_t batadv_vis_prim_sec(char *buff, const struct hlist_head *if_list)
+static void batadv_vis_data_read_prim_sec(struct seq_file *seq,
+					  const struct hlist_head *if_list)
 {
 	struct if_list_entry *entry;
 	struct hlist_node *pos;
-	size_t len = 0;
 
 	hlist_for_each_entry(entry, pos, if_list, list) {
 		if (entry->primary)
-			len += sprintf(buff + len, "PRIMARY, ");
+			seq_printf(seq, "PRIMARY, ");
 		else
-			len += sprintf(buff + len,  "SEC %pM, ", entry->addr);
+			seq_printf(seq,  "SEC %pM, ", entry->addr);
 	}
-
-	return len;
-}
-
-static size_t batadv_vis_cnt_prim_sec(struct hlist_head *if_list)
-{
-	struct if_list_entry *entry;
-	struct hlist_node *pos;
-	size_t count = 0;
-
-	hlist_for_each_entry(entry, pos, if_list, list) {
-		if (entry->primary)
-			count += 9;
-		else
-			count += 23;
-	}
-
-	return count;
 }
 
 /* read an entry  */
-static ssize_t batadv_vis_data_read_entry(char *buff,
+static ssize_t batadv_vis_data_read_entry(struct seq_file *seq,
 					  const struct vis_info_entry *entry,
 					  const uint8_t *src, bool primary)
 {
-	/* maximal length: max(4+17+2, 3+17+1+3+2) == 26 */
 	if (primary && entry->quality == 0)
-		return sprintf(buff, "TT %pM, ", entry->dest);
+		return seq_printf(seq, "TT %pM, ", entry->dest);
 	else if (batadv_compare_eth(entry->src, src))
-		return sprintf(buff, "TQ %pM %d, ", entry->dest,
-			       entry->quality);
+		return seq_printf(seq, "TQ %pM %d, ", entry->dest,
+				  entry->quality);
 
 	return 0;
 }
 
+static void batadv_vis_data_insert_interfaces(struct hlist_head *list,
+					      struct vis_packet *packet,
+					      struct vis_info_entry *entries)
+{
+	int i;
+
+	for (i = 0; i < packet->entries; i++) {
+		if (entries[i].quality == 0)
+			continue;
+
+		if (batadv_compare_eth(entries[i].src, packet->vis_orig))
+			continue;
+
+		batadv_vis_data_insert_interface(entries[i].src, list, false);
+	}
+}
+
+static void batadv_vis_data_read_entries(struct seq_file *seq,
+					 struct hlist_head *list,
+					 struct vis_packet *packet,
+					 struct vis_info_entry *entries)
+{
+	int i;
+	struct if_list_entry *entry;
+	struct hlist_node *pos;
+
+	hlist_for_each_entry(entry, pos, list, list) {
+		seq_printf(seq, "%pM,", entry->addr);
+
+		for (i = 0; i < packet->entries; i++)
+			batadv_vis_data_read_entry(seq, &entries[i],
+						   entry->addr, entry->primary);
+
+		/* add primary/secondary records */
+		if (batadv_compare_eth(entry->addr, packet->vis_orig))
+			batadv_vis_data_read_prim_sec(seq, list);
+
+		seq_printf(seq, "\n");
+	}
+}
+
+static void batadv_vis_seq_print_text_bucket(struct seq_file *seq,
+					     const struct hlist_head *head)
+{
+	struct hlist_node *node;
+	struct vis_info *info;
+	struct vis_packet *packet;
+	uint8_t *entries_pos;
+	struct vis_info_entry *entries;
+	struct if_list_entry *entry;
+	struct hlist_node *pos, *n;
+
+	HLIST_HEAD(vis_if_list);
+
+	hlist_for_each_entry_rcu(info, node, head, hash_entry) {
+		packet = (struct vis_packet *)info->skb_packet->data;
+		entries_pos = (uint8_t *)packet + sizeof(*packet);
+		entries = (struct vis_info_entry *)entries_pos;
+
+		batadv_vis_data_insert_interface(packet->vis_orig, &vis_if_list,
+						 true);
+		batadv_vis_data_insert_interfaces(&vis_if_list, packet,
+						  entries);
+		batadv_vis_data_read_entries(seq, &vis_if_list, packet,
+					     entries);
+
+		hlist_for_each_entry_safe(entry, pos, n, &vis_if_list, list) {
+			hlist_del(&entry->list);
+			kfree(entry);
+		}
+	}
+}
+
 int batadv_vis_seq_print_text(struct seq_file *seq, void *offset)
 {
 	struct hard_iface *primary_if;
-	struct hlist_node *node;
 	struct hlist_head *head;
-	struct vis_info *info;
-	struct vis_packet *packet;
-	struct vis_info_entry *entries;
 	struct net_device *net_dev = (struct net_device *)seq->private;
 	struct bat_priv *bat_priv = netdev_priv(net_dev);
 	struct hashtable_t *hash = bat_priv->vis_hash;
-	HLIST_HEAD(vis_if_list);
-	struct if_list_entry *entry;
-	struct hlist_node *pos, *n;
 	uint32_t i;
-	int j, ret = 0;
+	int ret = 0;
 	int vis_server = atomic_read(&bat_priv->vis_mode);
-	size_t buff_pos, buf_size;
-	char *buff;
 
 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (!primary_if)
@@ -214,120 +259,13 @@
 	if (vis_server == VIS_TYPE_CLIENT_UPDATE)
 		goto out;
 
-	buf_size = 1;
-	/* Estimate length */
 	spin_lock_bh(&bat_priv->vis_hash_lock);
 	for (i = 0; i < hash->size; i++) {
 		head = &hash->table[i];
-
-		rcu_read_lock();
-		hlist_for_each_entry_rcu(info, node, head, hash_entry) {
-			packet = (struct vis_packet *)info->skb_packet->data;
-			entries = (struct vis_info_entry *)
-				((char *)packet + sizeof(*packet));
-
-			batadv_vis_data_insert_interface(packet->vis_orig,
-							 &vis_if_list, true);
-
-			for (j = 0; j < packet->entries; j++) {
-				if (entries[j].quality == 0)
-					continue;
-				if (batadv_compare_eth(entries[j].src,
-						       packet->vis_orig))
-					continue;
-				batadv_vis_data_insert_interface(entries[j].src,
-								 &vis_if_list,
-								 false);
-			}
-
-			hlist_for_each_entry(entry, pos, &vis_if_list, list) {
-				buf_size += 18 + 26 * packet->entries;
-
-				/* add primary/secondary records */
-				if (batadv_compare_eth(entry->addr,
-						       packet->vis_orig))
-					buf_size +=
-					  batadv_vis_cnt_prim_sec(&vis_if_list);
-
-				buf_size += 1;
-			}
-
-			hlist_for_each_entry_safe(entry, pos, n, &vis_if_list,
-						  list) {
-				hlist_del(&entry->list);
-				kfree(entry);
-			}
-		}
-		rcu_read_unlock();
+		batadv_vis_seq_print_text_bucket(seq, head);
 	}
-
-	buff = kmalloc(buf_size, GFP_ATOMIC);
-	if (!buff) {
-		spin_unlock_bh(&bat_priv->vis_hash_lock);
-		ret = -ENOMEM;
-		goto out;
-	}
-	buff[0] = '\0';
-	buff_pos = 0;
-
-	for (i = 0; i < hash->size; i++) {
-		head = &hash->table[i];
-
-		rcu_read_lock();
-		hlist_for_each_entry_rcu(info, node, head, hash_entry) {
-			packet = (struct vis_packet *)info->skb_packet->data;
-			entries = (struct vis_info_entry *)
-				((char *)packet + sizeof(*packet));
-
-			batadv_vis_data_insert_interface(packet->vis_orig,
-							 &vis_if_list, true);
-
-			for (j = 0; j < packet->entries; j++) {
-				if (entries[j].quality == 0)
-					continue;
-				if (batadv_compare_eth(entries[j].src,
-						       packet->vis_orig))
-					continue;
-				batadv_vis_data_insert_interface(entries[j].src,
-								 &vis_if_list,
-								 false);
-			}
-
-			hlist_for_each_entry(entry, pos, &vis_if_list, list) {
-				buff_pos += sprintf(buff + buff_pos, "%pM,",
-						entry->addr);
-
-				for (j = 0; j < packet->entries; j++)
-					buff_pos += batadv_vis_data_read_entry(
-							buff + buff_pos,
-							&entries[j],
-							entry->addr,
-							entry->primary);
-
-				/* add primary/secondary records */
-				if (batadv_compare_eth(entry->addr,
-						       packet->vis_orig))
-					buff_pos +=
-					 batadv_vis_prim_sec(buff + buff_pos,
-							     &vis_if_list);
-
-				buff_pos += sprintf(buff + buff_pos, "\n");
-			}
-
-			hlist_for_each_entry_safe(entry, pos, n, &vis_if_list,
-						  list) {
-				hlist_del(&entry->list);
-				kfree(entry);
-			}
-		}
-		rcu_read_unlock();
-	}
-
 	spin_unlock_bh(&bat_priv->vis_hash_lock);
 
-	seq_printf(seq, "%s", buff);
-	kfree(buff);
-
 out:
 	if (primary_if)
 		batadv_hardif_free_ref(primary_if);