firewire: core: improve check for local node

My recently added test for a device being local in fw-cdev.c got it
slightly wrong:  Comparisons of node IDs are only valid if the
generation is current, which I forgot to check.  Normally, serialization
by card->lock takes care of this, but a device in FW_DEVICE_GONE state
will necessarily have a wrong generation and invalid node_id.

The "is it local?" check is made 100% correct and simpler now by means
of a struct fw_device flag which is set at fw_device creation.

Besides the fw-cdev site which was to be fixed, there is another site
which can make use of the new flag, and an RFC-2734 driver will benefit
from it too.

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

3 files changed, 4 insertions, 6 deletions

diff --git a/drivers/firewire/fw-cdev.c b/drivers/firewire/fw-cdev.c
index 7eb6594cc3e5..8a5e6ae2552c 100644
--- a/drivers/firewire/fw-cdev.c
+++ b/drivers/firewire/fw-cdev.c
@@ -739,15 +739,11 @@ static void release_descriptor(struct client *client,
 static int ioctl_add_descriptor(struct client *client, void *buffer)
 {
         struct fw_cdev_add_descriptor *request = buffer;
-        struct fw_card *card = client->device->card;
         struct descriptor_resource *r;
         int ret;
 
         /* Access policy: Allow this ioctl only on local nodes' device files. */
-        spin_lock_irq(&card->lock);
-        ret = client->device->node_id != card->local_node->node_id;
-        spin_unlock_irq(&card->lock);
-        if (ret)
+        if (!client->device->is_local)
                 return -ENOSYS;
 
         if (request->length > 256)
diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index a47e2129d83d..a38a68b97b58 100644
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -1042,6 +1042,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
                 device->node = fw_node_get(node);
                 device->node_id = node->node_id;
                 device->generation = card->generation;
+                device->is_local = node == card->local_node;
                 mutex_init(&device->client_list_mutex);
                 INIT_LIST_HEAD(&device->client_list);
 
@@ -1075,7 +1076,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
                             FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
                         PREPARE_DELAYED_WORK(&device->work, fw_device_refresh);
                         schedule_delayed_work(&device->work,
-                                node == card->local_node ? 0 : INITIAL_DELAY);
+                                device->is_local ? 0 : INITIAL_DELAY);
                 }
                 break;
 
diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 97588937c018..623cfee289bd 100644
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -80,6 +80,7 @@ struct fw_device {
         u32 *config_rom;
         size_t config_rom_length;
         int config_rom_retries;
+        unsigned is_local:1;
         unsigned cmc:1;
         unsigned bc_implemented:2;