From 7cc5bf9a3a84e5a02e23e5739fb894790b37c101 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 8 Jul 2008 11:58:21 -0700 Subject: 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 Signed-off-by: Dan Williams --- drivers/dma/dmaengine.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'drivers/dma') diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 99c22b42bad..10de69eb1a3 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); } -- cgit v1.2.3