firewire: core: use more outbound tlabels

Tlabel is a 6 bits wide datum.  Wrap it after 63 rather than 31 for more
safety against transaction label exhaustion and potential responders'
transaction layer bugs.  (As noted by Guus Sliepen, this change requires
an expansion of tlabel_mask to 64 bits.)
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/core-transaction.c

@@ -82,7 +82,7 @@ static int close_transaction(struct fw_transaction *transaction,
 	list_for_each_entry(t, &card->transaction_list, link) {
 		if (t == transaction) {
 			list_del(&t->link);
-			card->tlabel_mask &= ~(1 << t->tlabel);
+			card->tlabel_mask &= ~(1ULL << t->tlabel);
 			break;
 		}
 	}
@@ -288,14 +288,14 @@ void fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode,
 	spin_lock_irqsave(&card->lock, flags);
 
 	tlabel = card->current_tlabel;
-	if (card->tlabel_mask & (1 << tlabel)) {
+	if (card->tlabel_mask & (1ULL << tlabel)) {
 		spin_unlock_irqrestore(&card->lock, flags);
 		callback(card, RCODE_SEND_ERROR, NULL, 0, callback_data);
 		return;
 	}
 
-	card->current_tlabel = (card->current_tlabel + 1) & 0x1f;
-	card->tlabel_mask |= (1 << tlabel);
+	card->current_tlabel = (card->current_tlabel + 1) & 0x3f;
+	card->tlabel_mask |= (1ULL << tlabel);
 
 	t->node_id = destination_id;
 	t->tlabel = tlabel;

include/linux/firewire.h

@@ -98,7 +98,8 @@ struct fw_card {
 
 	int node_id;
 	int generation;
-	int current_tlabel, tlabel_mask;
+	int current_tlabel;
+	u64 tlabel_mask;
 	struct list_head transaction_list;
 	struct timer_list flush_timer;
 	unsigned long reset_jiffies;