dmaengine: protect 'id' from concurrent registrations

There is a possibility to have two devices registered with the same id.

Cc: <stable@kernel.org>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 5317e08..6579965 100644 (file)
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -388,7 +388,10 @@ int dma_async_device_register(struct dma_device *device)
 
        init_completion(&device->done);
        kref_init(&device->refcount);
+
+       mutex_lock(&dma_list_mutex);
        device->dev_id = id++;
+       mutex_unlock(&dma_list_mutex);
 
        /* represent channels in sysfs. Probably want devs too */
        list_for_each_entry(chan, &device->channels, device_node) {