firewire: fix "kobject_add failed for fw* with -EEXIST"
There is a race between shutdown and creation of devices: fw-core may
attempt to add a device with the same name of an already existing
device. http://bugzilla.kernel.org/show_bug.cgi?id=9828
Impact of the bug: Happens rarely (when shutdown of a device coincides
with creation of another), forces the user to unplug and replug the new
device to get it working.
The fix is obvious: Free the minor number *after* instead of *before*
device_unregister(). This requires to take an additional reference of
the fw_device as long as the IDR tree points to it.
And while we are at it, we fix an additional race condition:
fw_device_op_open() took its reference of the fw_device a little bit too
late, hence was in danger to access an already invalid fw_device.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-cdev.c b/drivers/firewire/fw-cdev.c
index 7e73cba..44ccee2 100644
--- a/drivers/firewire/fw-cdev.c
+++ b/drivers/firewire/fw-cdev.c
@@ -109,15 +109,17 @@
struct client *client;
unsigned long flags;
- device = fw_device_from_devt(inode->i_rdev);
+ device = fw_device_get_by_devt(inode->i_rdev);
if (device == NULL)
return -ENODEV;
client = kzalloc(sizeof(*client), GFP_KERNEL);
- if (client == NULL)
+ if (client == NULL) {
+ fw_device_put(device);
return -ENOMEM;
+ }
- client->device = fw_device_get(device);
+ client->device = device;
INIT_LIST_HEAD(&client->event_list);
INIT_LIST_HEAD(&client->resource_list);
spin_lock_init(&client->lock);