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>

5 files changed, 17 insertions, 4 deletions

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 11fc81500f82..6c316cfe70c4 100644
--- a/drivers/firewire/core-card.c
+++ b/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);
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 9b8df2039155..d8ac0ce2d6bf 100644
--- a/drivers/firewire/core-cdev.c
+++ b/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;
 
diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
index 56e908ba43f1..88d5133ae702 100644
--- a/drivers/firewire/core-topology.c
+++ b/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);
 
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index 8b9b27373219..d31022b05bd9 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -66,6 +66,10 @@ struct fw_cdev_event_common {
  * This event is sent when the bus the device belongs to goes through a bus
  * reset.  It provides information about the new bus configuration, such as
  * new node ID for this device, new root ID, and others.
+ *
+ * If @bm_node_id is 0xffff right after bus reset it can be reread by an
+ * %FW_CDEV_IOC_GET_INFO ioctl after bus manager selection was finished.
+ * Kernels with ABI version < 4 do not set @bm_node_id.
  */
 struct fw_cdev_event_bus_reset {
         __u64 closure;
@@ -348,6 +352,7 @@ union fw_cdev_event {
  *  3  (2.6.34)  - made &fw_cdev_get_cycle_timer reliable
  *               - added %FW_CDEV_IOC_GET_CYCLE_TIMER2
  *  4  (2.6.36)  - added %FW_CDEV_EVENT_REQUEST2
+ *               - implemented &fw_cdev_event_bus_reset.bm_node_id
  */
 #define FW_CDEV_VERSION 3 /* Meaningless; don't use this macro. */
 
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index e44b502c8341..db30a752a87a 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -119,6 +119,7 @@ struct fw_card {
         int bm_retries;
         int bm_generation;
         __be32 bm_transaction_data[2];
+        int bm_node_id;
         bool bm_abdicate;
 
         bool priority_budget_implemented;       /* controller feature */