[ 03/59] rtlwifi: Add missing DMA buffer unmapping for PCI drivers

From: Greg KH
Date: Thu Apr 19 2012 - 17:52:06 EST

3.0-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

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
@@ -954,8 +954,13 @@ 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);
+ }

/*NB: the beacon data buffer must be 32-bit aligned. */
pskb = ieee80211_beacon_get(hw, mac->vif);

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