firewire: Don't set card->irm_node before we have a new valid topology.

In case the topology build fails, we want to retain the old topology
info until another reset finishes and results in a valid new tree.  If
we clear card->irm_node to NULL and the topology build fails, we end up
dereferencing a NULL pointer in a few places.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

diff --git a/drivers/firewire/fw-topology.c b/drivers/firewire/fw-topology.c
index 7923463..bc8a348 100644 (file)
--- a/drivers/firewire/fw-topology.c
+++ b/drivers/firewire/fw-topology.c
@@ -166,7 +166,7 @@ static void update_hop_count(struct fw_node *node)
 static struct fw_node *build_tree(struct fw_card *card,
                                  u32 *sid, int self_id_count)
 {
-       struct fw_node *node, *child, *local_node;
+       struct fw_node *node, *child, *local_node, *irm_node;
        struct list_head stack, *h;
        u32 *next_sid, *end, q;
        int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
@@ -178,7 +178,7 @@ static struct fw_node *build_tree(struct fw_card *card,
        stack_depth = 0;
        end = sid + self_id_count;
        phy_id = 0;
-       card->irm_node = NULL;
+       irm_node = NULL;
        gap_count = self_id_gap_count(*sid);
        topology_type = 0;
 
@@ -218,7 +218,7 @@ static struct fw_node *build_tree(struct fw_card *card,
                        local_node = node;
 
                if (self_id_contender(q))
-                       card->irm_node = node;
+                       irm_node = node;
 
                if (node->phy_speed == SCODE_BETA)
                        topology_type |= FW_TOPOLOGY_B;
@@ -282,6 +282,7 @@ static struct fw_node *build_tree(struct fw_card *card,
        }
 
        card->root_node = node;
+       card->irm_node = irm_node;
        card->gap_count = gap_count;
        card->topology_type = topology_type;