The patch titled
dmaengine: fix broken device refcounting
has been added to the -mm tree. Its filename is
dmaengine-fix-broken-device-refcounting.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: dmaengine: fix broken device refcounting
From: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
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@xxxxxxxxx: kill unnecessary client refcounting]
Signed-off-by: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Shannon Nelson <shannon.nelson@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/dma/dmaengine.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
diff -puN drivers/dma/dmaengine.c~dmaengine-fix-broken-device-refcounting drivers/dma/dmaengine.c
--- a/drivers/dma/dmaengine.c~dmaengine-fix-broken-device-refcounting
+++ a/drivers/dma/dmaengine.c
@@ -183,10 +183,9 @@ 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;
}
}
@@ -273,11 +272,8 @@ 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);
@@ -317,11 +313,8 @@ 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);
@@ -398,6 +391,8 @@ 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;
_
Patches currently in -mm which might be from hskinnemoen@xxxxxxxxx are
dmaengine-fix-broken-device-refcounting.patch
git-avr32.patch
git-mtd.patch
read_current_time-cleanups.patch
sanitize-the-type-of-struct-useru_ar0.patch
add-cmpxchg_local-to-avr32.patch
-
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