[ 09/75] rtlwifi: Add missing DMA buffer unmapping for PCI drivers

[Greg KH]

3.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Larry Finger <Larry.Finger@xxxxxxxxxxxx>

commit 673f7786e205c87b5d978c62827b9a66d097bebb upstream.

In https://bugzilla.kernel.org/show_bug.cgi?id=42976, a system with driver
rtl8192se used as an AP suffers from "Out of SW-IOMMU space" errors. These
are caused by the DMA buffers used for beacons never being unmapped.

This bug was also reported at
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/961618

Reported-and-Tested-by: Da Xue <da@xxxxxxxxxxxxxxxx>
Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/wireless/rtlwifi/pci.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/rtlwifi/pci.c
+++ b/drivers/net/wireless/rtlwifi/pci.c
@@ -921,8 +921,13 @@ static void _rtl_pci_prepare_bcn_tasklet
 	memset(&tcb_desc, 0, sizeof(struct rtl_tcb_desc));
 	ring = &rtlpci->tx_ring[BEACON_QUEUE];
 	pskb = __skb_dequeue(&ring->queue);
-	if (pskb)
+	if (pskb) {
+		struct rtl_tx_desc *entry = &ring->desc[ring->idx];
+		pci_unmap_single(rtlpci->pdev, rtlpriv->cfg->ops->get_desc(
+				 (u8 *) entry, true, HW_DESC_TXBUFF_ADDR),
+				 pskb->len, PCI_DMA_TODEVICE);
 		kfree_skb(pskb);
+	}
 
 	/*NB: the beacon data buffer must be 32-bit aligned. */
 	pskb = ieee80211_beacon_get(hw, mac->vif);


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