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authorHaavard Skinnemoen <hskinnemoen@atmel.com>2007-11-14 16:59:27 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-14 18:45:39 -0800
commit348badf1e825323c419dd118f65783db0f7d2ec8 (patch)
tree126cddb26c14233eaff8ddd6a240fe4ac69204ee
parent90d8dabf74179e6615bd4688a118e12ec29ab7aa (diff)
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 <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>
-rw-r--r--drivers/dma/dmaengine.c17
1 files changed, 6 insertions, 11 deletions
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;