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dmaengine: fix broken device refcounting

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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 <hskinnemoen@atmel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Haavard Skinnemoen 2007-11-14 16:59:27 -08:00 committed by Linus Torvalds
parent 90d8dabf74
commit 348badf1e8
1 changed files with 6 additions and 11 deletions
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17
drivers/dma/dmaengine.c
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@ -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;