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, forces the user to unplug and replug
the new device to get it working.
The fix moves deregistration of the minor number and device_unregister()
into a common rw_sem protected section.
We also move the ref count increment from fw_device_op_open into an
rw_sem protected section with the lookup of the device, so that the
device pointer can't become invalid between lookup and usage.
Signed-off-by: Stefan Richter <[EMAIL PROTECTED]>
---
drivers/firewire/fw-cdev.c | 6 ++++--
drivers/firewire/fw-device.c | 10 ++++++----
2 files changed, 10 insertions(+), 6 deletions(-)
Index: linux/drivers/firewire/fw-device.c
===================================================================
--- linux.orig/drivers/firewire/fw-device.c
+++ linux/drivers/firewire/fw-device.c
@@ -614,10 +614,12 @@ struct fw_device *fw_device_from_devt(de
{
struct fw_device *device;
down_read(&idr_rwsem);
device = idr_find(&fw_device_idr, MINOR(devt));
+ if (device)
+ fw_device_get(device);
up_read(&idr_rwsem);
return device;
}
@@ -625,17 +627,17 @@ static void fw_device_shutdown(struct wo
{
struct fw_device *device =
container_of(work, struct fw_device, work.work);
int minor = MINOR(device->device.devt);
- down_write(&idr_rwsem);
- idr_remove(&fw_device_idr, minor);
- up_write(&idr_rwsem);
-
fw_device_cdev_remove(device);
device_for_each_child(&device->device, NULL, shutdown_unit);
+
+ down_write(&idr_rwsem);
device_unregister(&device->device);
+ idr_remove(&fw_device_idr, minor);
+ up_write(&idr_rwsem);
}
static struct device_type fw_device_type = {
.release = fw_device_release,
};
Index: linux/drivers/firewire/fw-cdev.c
===================================================================
--- linux.orig/drivers/firewire/fw-cdev.c
+++ linux/drivers/firewire/fw-cdev.c
@@ -112,14 +112,16 @@ static int fw_device_op_open(struct inod
device = fw_device_from_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);
init_waitqueue_head(&client->wait);
--
Stefan Richter
-=====-==--- ---= ==-==
http://arcgraph.de/sr/
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