ath9k: Synchronize DMA transfer with CPU at right place

This patch does pci_dma_sync_single_for_cpu() before accessing
the header of the frame and queueing the same buffer into h/w.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/net/wireless/ath9k/recv.c b/drivers/net/wireless/ath9k/recv.c
index cc160fe9f817..462e08c3d09d 100644
--- a/drivers/net/wireless/ath9k/recv.c
+++ b/drivers/net/wireless/ath9k/recv.c
@@ -520,6 +520,15 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
                         continue;
 
                 /*
+                 * Synchronize the DMA transfer with CPU before
+                 * 1. accessing the frame
+                 * 2. requeueing the same buffer to h/w
+                 */
+                pci_dma_sync_single_for_cpu(sc->pdev, bf->bf_buf_addr,
+                                sc->rx.bufsize,
+                                PCI_DMA_FROMDEVICE);
+
+                /*
                  * If we're asked to flush receive queue, directly
                  * chain it back at the queue without processing it.
                  */
@@ -547,10 +556,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
                 if (!requeue_skb)
                         goto requeue;
 
-                /* Sync and unmap the frame */
-                pci_dma_sync_single_for_cpu(sc->pdev, bf->bf_buf_addr,
-                                            sc->rx.bufsize,
-                                            PCI_DMA_FROMDEVICE);
+                /* Unmap the frame */
                 pci_unmap_single(sc->pdev, bf->bf_buf_addr,
                                  sc->rx.bufsize,
                                  PCI_DMA_FROMDEVICE);