ath9k: Check for pci_map_single() errors

pci_map_single() can fail so detect those errors with
pci_dma_mapping_error() and deal with them accordingly.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/beacon.c b/drivers/net/wireless/ath9k/beacon.c
index fe6929d..507299b 100644
--- a/drivers/net/wireless/ath9k/beacon.c
+++ b/drivers/net/wireless/ath9k/beacon.c
@@ -190,6 +190,13 @@
 		pci_map_single(sc->pdev, skb->data,
 			       skb->len,
 			       PCI_DMA_TODEVICE);
+	if (unlikely(pci_dma_mapping_error(sc->pdev, bf->bf_buf_addr))) {
+		dev_kfree_skb_any(skb);
+		bf->bf_mpdu = NULL;
+		DPRINTF(sc, ATH_DBG_CONFIG,
+			"pci_dma_mapping_error() on beaconing\n");
+		return NULL;
+	}
 
 	skb = ieee80211_get_buffered_bc(sc->hw, vif);
 
@@ -392,11 +399,18 @@
 		memcpy(&hdr[1], &val, sizeof(val));
 	}
 
+	bf->bf_mpdu = skb;
 	bf->bf_buf_addr = bf->bf_dmacontext =
 		pci_map_single(sc->pdev, skb->data,
 			       skb->len,
 			       PCI_DMA_TODEVICE);
-	bf->bf_mpdu = skb;
+	if (unlikely(pci_dma_mapping_error(sc->pdev, bf->bf_buf_addr))) {
+		dev_kfree_skb_any(skb);
+		bf->bf_mpdu = NULL;
+		DPRINTF(sc, ATH_DBG_CONFIG,
+			"pci_dma_mapping_error() on beacon alloc\n");
+		return -ENOMEM;
+	}
 
 	return 0;
 }