1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/net/wireless/ath9k/recv.c b/drivers/net/wireless/ath9k/recv.c
index 4983402af559..504a0444d89f 100644
--- a/drivers/net/wireless/ath9k/recv.c
+++ b/drivers/net/wireless/ath9k/recv.c
@@ -49,10 +49,12 @@ static void ath_rx_buf_link(struct ath_softc *sc, struct ath_buf *bf)
         ASSERT(skb != NULL);
         ds->ds_vdata = skb->data;
 
-        /* setup rx descriptors */
+        /* setup rx descriptors. The sc_rxbufsize here tells the harware
+         * how much data it can DMA to us and that we are prepared
+         * to process */
         ath9k_hw_setuprxdesc(ah,
                              ds,
-                             skb_tailroom(skb),   /* buffer size */
+                             sc->sc_rxbufsize,
                              0);
 
         if (sc->sc_rxlink == NULL)
@@ -398,6 +400,13 @@ static struct sk_buff *ath_rxbuf_alloc(struct ath_softc *sc,
          * in rx'd frames.
          */
 
+        /* Note: the kernel can allocate a value greater than
+         * what we ask it to give us. We really only need 4 KB as that
+         * is this hardware supports and in fact we need at least 3849
+         * as that is the MAX AMSDU size this hardware supports.
+         * Unfortunately this means we may get 8 KB here from the
+         * kernel... and that is actually what is observed on some
+         * systems :( */
         skb = dev_alloc_skb(len + sc->sc_cachelsz - 1);
         if (skb != NULL) {
                 off = ((unsigned long) skb->data) % sc->sc_cachelsz;
@@ -456,7 +465,7 @@ static int ath_rx_indicate(struct ath_softc *sc,
         if (nskb != NULL) {
                 bf->bf_mpdu = nskb;
                 bf->bf_buf_addr = pci_map_single(sc->pdev, nskb->data,
-                                         skb_end_pointer(nskb) - nskb->head,
+                                         sc->sc_rxbufsize,
                                          PCI_DMA_FROMDEVICE);
                 bf->bf_dmacontext = bf->bf_buf_addr;
                 ATH_RX_CONTEXT(nskb)->ctx_rxbuf = bf;
@@ -542,7 +551,7 @@ int ath_rx_init(struct ath_softc *sc, int nbufs)
 
                         bf->bf_mpdu = skb;
                         bf->bf_buf_addr = pci_map_single(sc->pdev, skb->data,
-                                         skb_end_pointer(skb) - skb->head,
+                                         sc->sc_rxbufsize,
                                          PCI_DMA_FROMDEVICE);
                         bf->bf_dmacontext = bf->bf_buf_addr;
                         ATH_RX_CONTEXT(skb)->ctx_rxbuf = bf;
@@ -1007,7 +1016,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
 
                 pci_dma_sync_single_for_cpu(sc->pdev,
                                             bf->bf_buf_addr,
-                                            skb_tailroom(skb),
+                                            sc->sc_rxbufsize,
                                             PCI_DMA_FROMDEVICE);
                 pci_unmap_single(sc->pdev,
                                  bf->bf_buf_addr,