2.6.23-stable review patch. If anyone has any objections, please let us know. ------------------ From: Haavard Skinnemoen patch 348badf1e825323c419dd118f65783db0f7d2ec8 in mainline. When a DMA device is unregistered, its reference count is decremented twice for each channel: Once dma_class_dev_release() and once in dma_chan_cleanup(). This may result in the DMA device driver's remove() function completing before all channels have been cleaned up, causing lots of use-after-free fun. Fix it by incrementing the device's reference count twice for each channel during registration. [dan.j.williams@intel.com: kill unnecessary client refcounting] Signed-off-by: Haavard Skinnemoen Signed-off-by: Dan Williams Signed-off-by: Shannon Nelson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/dma/dmaengine.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -182,10 +182,9 @@ static void dma_client_chan_alloc(struct /* we are done once this client rejects * an available resource */ - if (ack == DMA_ACK) { + if (ack == DMA_ACK) dma_chan_get(chan); - kref_get(&device->refcount); - } else if (ack == DMA_NAK) + else if (ack == DMA_NAK) return; } } @@ -272,11 +271,8 @@ static void dma_clients_notify_removed(s /* client was holding resources for this channel so * free it */ - if (ack == DMA_ACK) { + if (ack == DMA_ACK) dma_chan_put(chan); - kref_put(&chan->device->refcount, - dma_async_device_cleanup); - } } mutex_unlock(&dma_list_mutex); @@ -316,11 +312,8 @@ void dma_async_client_unregister(struct ack = client->event_callback(client, chan, DMA_RESOURCE_REMOVED); - if (ack == DMA_ACK) { + if (ack == DMA_ACK) dma_chan_put(chan); - kref_put(&chan->device->refcount, - dma_async_device_cleanup); - } } list_del(&client->global_node); @@ -397,6 +390,8 @@ int dma_async_device_register(struct dma goto err_out; } + /* One for the channel, one of the class device */ + kref_get(&device->refcount); kref_get(&device->refcount); kref_init(&chan->refcount); chan->slow_ref = 0; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/