NTB: correct dmaengine_get/put usage

dmaengine_get() causes the initialization of the per-cpu channel tables.
It needs to be called prior to dma_find_channel().

Initial version by Dan Williams <dan.j.williams@intel.com>

Signed-off-by: Jon Mason <jon.mason@intel.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 7010f23dab18..172501d47600 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1419,11 +1419,12 @@ ntb_transport_create_queue(void *data, struct pci_dev *pdev,
         qp->tx_handler = handlers->tx_handler;
         qp->event_handler = handlers->event_handler;
 
+        dmaengine_get();
         qp->dma_chan = dma_find_channel(DMA_MEMCPY);
-        if (!qp->dma_chan)
+        if (!qp->dma_chan) {
+                dmaengine_put();
                 dev_info(&pdev->dev, "Unable to allocate DMA channel, using CPU instead\n");
-        else
-                dmaengine_get();
+        }
 
         for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
                 entry = kzalloc(sizeof(struct ntb_queue_entry), GFP_ATOMIC);
@@ -1464,6 +1465,8 @@ err2:
 err1:
         while ((entry = ntb_list_rm(&qp->ntb_rx_free_q_lock, &qp->rx_free_q)))
                 kfree(entry);
+        if (qp->dma_chan)
+                dmaengine_put();
         set_bit(free_queue, &nt->qp_bitmap);
 err:
         return NULL;