firewire: fill_bus_reset_event needs lock protection
Callers of fill_bus_reset_event() have to take card->lock. Otherwise
access to node data may oops if node removal is in progress.
A lockless alternative would be
- event->local_node_id = card->local_node->node_id;
+ tmp = fw_node_get(card->local_node);
+ event->local_node_id = tmp->node_id;
+ fw_node_put(tmp);
and ditto with the other node pointers which fill_bus_reset_event()
accesses. But I went the locked route because one of the two callers
already holds the lock. As a bonus, we don't need the memory barrier
anymore because device->generation and device->node_id are written in
a card->lock protected section.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
diff --git a/drivers/firewire/fw-cdev.c b/drivers/firewire/fw-cdev.c
index dda1401..c639915 100644
--- a/drivers/firewire/fw-cdev.c
+++ b/drivers/firewire/fw-cdev.c
@@ -205,6 +205,7 @@
return dequeue_event(client, buffer, count);
}
+/* caller must hold card->lock so that node pointers can be dereferenced here */
static void
fill_bus_reset_event(struct fw_cdev_event_bus_reset *event,
struct client *client)
@@ -214,7 +215,6 @@
event->closure = client->bus_reset_closure;
event->type = FW_CDEV_EVENT_BUS_RESET;
event->generation = client->device->generation;
- smp_rmb(); /* node_id must not be older than 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. */
@@ -274,6 +274,7 @@
{
struct fw_cdev_get_info *get_info = buffer;
struct fw_cdev_event_bus_reset bus_reset;
+ struct fw_card *card = client->device->card;
unsigned long ret = 0;
client->version = get_info->version;
@@ -299,13 +300,17 @@
client->bus_reset_closure = get_info->bus_reset_closure;
if (get_info->bus_reset != 0) {
void __user *uptr = u64_to_uptr(get_info->bus_reset);
+ unsigned long flags;
+ spin_lock_irqsave(&card->lock, flags);
fill_bus_reset_event(&bus_reset, client);
+ spin_unlock_irqrestore(&card->lock, flags);
+
if (copy_to_user(uptr, &bus_reset, sizeof(bus_reset)))
return -EFAULT;
}
- get_info->card = client->device->card->index;
+ get_info->card = card->index;
return 0;
}