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authorDan Williams <dan.j.williams@intel.com>2008-07-08 22:58:21 +0400
committerDan Williams <dan.j.williams@intel.com>2008-07-08 22:58:21 +0400
commit7cc5bf9a3a84e5a02e23e5739fb894790b37c101 (patch)
treeb526b348ed1b64884bf672924540bb5dc29cb211 /drivers/dma
parent9c402f4e196290692d998b188f9094deb1619e57 (diff)
downloadlinux-7cc5bf9a3a84e5a02e23e5739fb894790b37c101.tar.xz
dmaengine: track the number of clients using a channel
Haavard's dma-slave interface would like to test for exclusive access to a channel. The standard channel refcounting is not sufficient in that it tracks more than just client references, it is also inaccurate as reference counts are percpu until the channel is removed. This change also enables a future fix to deallocate resources when a client declines to use a capable channel. Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/dmaengine.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 99c22b42bada..10de69eb1a3e 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -183,9 +183,10 @@ 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);
- else if (ack == DMA_NAK)
+ chan->client_count++;
+ } else if (ack == DMA_NAK)
return;
}
}
@@ -272,8 +273,10 @@ 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);
+ chan->client_count--;
+ }
}
mutex_unlock(&dma_list_mutex);
@@ -313,8 +316,10 @@ 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);
+ chan->client_count--;
+ }
}
list_del(&client->global_node);
@@ -394,6 +399,7 @@ int dma_async_device_register(struct dma_device *device)
kref_get(&device->refcount);
kref_get(&device->refcount);
kref_init(&chan->refcount);
+ chan->client_count = 0;
chan->slow_ref = 0;
INIT_RCU_HEAD(&chan->rcu);
}