mwifiex: fix hang issue for USB chipsets

Bug 60815 - Interface hangs in mwifiex_usb
https://bugzilla.kernel.org/show_bug.cgi?id=60815

We have 4 bytes of interface header for packets delivered to SDIO
and PCIe, but not for USB interface.

In Tx AMSDU case, currently 4 bytes of garbage data is unnecessarily
appended for USB packets. This sometimes leads to a firmware hang,
because it may not interpret the data packet correctly.

Problem is fixed by removing this redundant headroom for USB.

Cc: <stable@vger.kernel.org> # 3.5+
Tested-by: Dmitry Khromov <icechrome@gmail.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/11n_aggr.c

@@ -150,7 +150,7 @@ mwifiex_11n_form_amsdu_txpd(struct mwifiex_private *priv,
  */
 int
 mwifiex_11n_aggregate_pkt(struct mwifiex_private *priv,
-			  struct mwifiex_ra_list_tbl *pra_list, int headroom,
+			  struct mwifiex_ra_list_tbl *pra_list,
 			  int ptrindex, unsigned long ra_list_flags)
 			  __releases(&priv->wmm.ra_list_spinlock)
 {
@@ -160,6 +160,7 @@ mwifiex_11n_aggregate_pkt(struct mwifiex_private *priv,
 	int pad = 0, ret;
 	struct mwifiex_tx_param tx_param;
 	struct txpd *ptx_pd = NULL;
+	int headroom = adapter->iface_type == MWIFIEX_USB ? 0 : INTF_HEADER_LEN;
 
 	skb_src = skb_peek(&pra_list->skb_head);
 	if (!skb_src) {

drivers/net/wireless/mwifiex/11n_aggr.h

@@ -26,7 +26,7 @@
 int mwifiex_11n_deaggregate_pkt(struct mwifiex_private *priv,
 				struct sk_buff *skb);
 int mwifiex_11n_aggregate_pkt(struct mwifiex_private *priv,
-			      struct mwifiex_ra_list_tbl *ptr, int headroom,
+			      struct mwifiex_ra_list_tbl *ptr,
 			      int ptr_index, unsigned long flags)
 			      __releases(&priv->wmm.ra_list_spinlock);
 

drivers/net/wireless/mwifiex/wmm.c

@@ -1239,8 +1239,7 @@ mwifiex_dequeue_tx_packet(struct mwifiex_adapter *adapter)
 		if (enable_tx_amsdu && mwifiex_is_amsdu_allowed(priv, tid) &&
 		    mwifiex_is_11n_aggragation_possible(priv, ptr,
 							adapter->tx_buf_size))
-			mwifiex_11n_aggregate_pkt(priv, ptr, INTF_HEADER_LEN,
-						  ptr_index, flags);
+			mwifiex_11n_aggregate_pkt(priv, ptr, ptr_index, flags);
 			/* ra_list_spinlock has been freed in
 			   mwifiex_11n_aggregate_pkt() */
 		else