From 348badf1e825323c419dd118f65783db0f7d2ec8 Mon Sep 17 00:00:00 2001 From: Haavard Skinnemoen Date: Wed, 14 Nov 2007 16:59:27 -0800 Subject: dmaengine: fix broken device refcounting 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 Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/dma/dmaengine.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) (limited to 'drivers/dma/dmaengine.c') diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 82489923af0..d59b2f41730 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -182,10 +182,9 @@ static void dma_client_chan_alloc(struct dma_client *client) /* 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(struct dma_chan *chan) /* 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 dma_client *client) 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_device *device) 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; -- cgit v1.2.3