static DEFINE_XARRAY_FLAGS(clients, XA_FLAGS_ALLOC);
static DECLARE_RWSEM(clients_rwsem);
+static void ib_client_put(struct ib_client *client)
+{
+ if (refcount_dec_and_test(&client->uses))
+ complete(&client->uses_zero);
+}
+
/*
* If client_data is registered then the corresponding client must also still
* be registered.
return 0;
down_write(&device->client_data_rwsem);
+ /*
+ * So long as the client is registered hold both the client and device
+ * unregistration locks.
+ */
+ if (!refcount_inc_not_zero(&client->uses))
+ goto out_unlock;
+ refcount_inc(&device->refcount);
+
/*
* Another caller to add_client_context got here first and has already
* completely initialized context.
return 0;
out:
+ ib_device_put(device);
+ ib_client_put(client);
+out_unlock:
up_write(&device->client_data_rwsem);
return ret;
}
client_data = xa_load(&device->client_data, client_id);
xa_clear_mark(&device->client_data, client_id, CLIENT_DATA_REGISTERED);
client = xa_load(&clients, client_id);
- downgrade_write(&device->client_data_rwsem);
+ up_write(&device->client_data_rwsem);
/*
* Notice we cannot be holding any exclusive locks when calling the
*
* For this reason clients and drivers should not call the
* unregistration functions will holdling any locks.
- *
- * It tempting to drop the client_data_rwsem too, but this is required
- * to ensure that unregister_client does not return until all clients
- * are completely unregistered, which is required to avoid module
- * unloading races.
*/
if (client->remove)
client->remove(device, client_data);
xa_erase(&device->client_data, client_id);
- up_read(&device->client_data_rwsem);
+ ib_device_put(device);
+ ib_client_put(client);
}
static int alloc_port_data(struct ib_device *device)
unsigned long index;
int ret;
+ refcount_set(&client->uses, 1);
+ init_completion(&client->uses_zero);
ret = assign_client_id(client);
if (ret)
return ret;
unsigned long index;
down_write(&clients_rwsem);
+ ib_client_put(client);
xa_clear_mark(&clients, client->client_id, CLIENT_REGISTERED);
up_write(&clients_rwsem);
+
+ /* We do not want to have locks while calling client->remove() */
+ rcu_read_lock();
+ xa_for_each (&devices, index, device) {
+ if (!ib_device_try_get(device))
+ continue;
+ rcu_read_unlock();
+
+ remove_client_context(device, client->client_id);
+
+ ib_device_put(device);
+ rcu_read_lock();
+ }
+ rcu_read_unlock();
+
/*
- * Every device still known must be serialized to make sure we are
- * done with the client callbacks before we return.
+ * remove_client_context() is not a fence, it can return even though a
+ * removal is ongoing. Wait until all removals are completed.
*/
- down_read(&devices_rwsem);
- xa_for_each (&devices, index, device)
- remove_client_context(device, client->client_id);
- up_read(&devices_rwsem);
+ wait_for_completion(&client->uses_zero);
down_write(&clients_rwsem);
list_del(&client->list);