firewire: cdev: fix fw_cdev_event_bus_reset.bm_node_id

Fix an obscure ABI feature that is a bit of a hassle to implement.
However, somebody put it into the ABI, so let's fill in a sensible
value there.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/core-card.c

@@ -239,7 +239,7 @@ static void fw_card_bm_work(struct work_struct *work)
 	struct fw_card *card = container_of(work, struct fw_card, work.work);
 	struct fw_device *root_device;
 	struct fw_node *root_node;
-	int root_id, new_root_id, irm_id, local_id;
+	int root_id, new_root_id, irm_id, bm_id, local_id;
 	int gap_count, generation, grace, rcode;
 	bool do_reset = false;
 	bool root_device_is_running;
@@ -301,9 +301,15 @@ static void fw_card_bm_work(struct work_struct *work)
 			/* Another bus reset, BM work has been rescheduled. */
 			goto out;
 
-		if (rcode == RCODE_COMPLETE &&
-		    card->bm_transaction_data[0] != cpu_to_be32(0x3f)) {
+		bm_id = be32_to_cpu(card->bm_transaction_data[0]);
 
+		spin_lock_irq(&card->lock);
+		if (rcode == RCODE_COMPLETE && generation == card->generation)
+			card->bm_node_id =
+			    bm_id == 0x3f ? local_id : 0xffc0 | bm_id;
+		spin_unlock_irq(&card->lock);
+
+		if (rcode == RCODE_COMPLETE && bm_id != 0x3f) {
 			/* Somebody else is BM.  Only act as IRM. */
 			if (local_id == irm_id)
 				allocate_broadcast_channel(card, generation);

drivers/firewire/core-cdev.c

@@ -318,7 +318,7 @@ static void fill_bus_reset_event(struct fw_cdev_event_bus_reset *event,
 	event->generation    = client->device->generation;
 	event->node_id       = client->device->node_id;
 	event->local_node_id = card->local_node->node_id;
-	event->bm_node_id    = 0; /* FIXME: We don't track the BM. */
+	event->bm_node_id    = card->bm_node_id;
 	event->irm_node_id   = card->irm_node->node_id;
 	event->root_node_id  = card->root_node->node_id;
 

drivers/firewire/core-topology.c

@@ -552,6 +552,7 @@ void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
 	smp_wmb();
 	card->generation = generation;
 	card->reset_jiffies = jiffies;
+	card->bm_node_id  = 0xffff;
 	card->bm_abdicate = bm_abdicate;
 	fw_schedule_bm_work(card, 0);