mwifiex: correct AMSDU aggregation check

The commit "mwifiex: remove list traversal.."(fcf2176c87..)
wrongly modifies AMSDU aggregation check. Due to this even though
packet size for iperf traffic is already large, we unnecessarily
try to aggregate them which adds some delay. If Tx iperf is started
on UUT for 30 seconds, UUT keeps sending Tx packets for few more
seconds.

That commit is reverted to fix the problem.
Also, MIN_NUM_AMSDU check is moved inside the loop to optimize the
loop.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/mwifiex/11n_aggr.c b/drivers/net/wireless/mwifiex/11n_aggr.c
index 1a453a6..9e63d16 100644
--- a/drivers/net/wireless/mwifiex/11n_aggr.c
+++ b/drivers/net/wireless/mwifiex/11n_aggr.c
@@ -193,7 +193,6 @@
 		skb_src = skb_dequeue(&pra_list->skb_head);
 
 		pra_list->total_pkts_size -= skb_src->len;
-		pra_list->total_pkts--;
 
 		atomic_dec(&priv->wmm.tx_pkts_queued);
 
@@ -269,7 +268,6 @@
 		skb_queue_tail(&pra_list->skb_head, skb_aggr);
 
 		pra_list->total_pkts_size += skb_aggr->len;
-		pra_list->total_pkts++;
 
 		atomic_inc(&priv->wmm.tx_pkts_queued);
 
diff --git a/drivers/net/wireless/mwifiex/11n_aggr.h b/drivers/net/wireless/mwifiex/11n_aggr.h
index 9c6dca7..900e1c6 100644
--- a/drivers/net/wireless/mwifiex/11n_aggr.h
+++ b/drivers/net/wireless/mwifiex/11n_aggr.h
@@ -21,6 +21,7 @@
 #define _MWIFIEX_11N_AGGR_H_
 
 #define PKT_TYPE_AMSDU	0xE6
+#define MIN_NUM_AMSDU 2
 
 int mwifiex_11n_deaggregate_pkt(struct mwifiex_private *priv,
 				struct sk_buff *skb);
diff --git a/drivers/net/wireless/mwifiex/main.h b/drivers/net/wireless/mwifiex/main.h
index 4f40428..907ab74 100644
--- a/drivers/net/wireless/mwifiex/main.h
+++ b/drivers/net/wireless/mwifiex/main.h
@@ -173,7 +173,6 @@
 	struct sk_buff_head skb_head;
 	u8 ra[ETH_ALEN];
 	u32 total_pkts_size;
-	u32 total_pkts;
 	u32 is_11n_enabled;
 };
 
diff --git a/drivers/net/wireless/mwifiex/wmm.c b/drivers/net/wireless/mwifiex/wmm.c
index 69e260b..eda2447 100644
--- a/drivers/net/wireless/mwifiex/wmm.c
+++ b/drivers/net/wireless/mwifiex/wmm.c
@@ -121,7 +121,6 @@
 	memcpy(ra_list->ra, ra, ETH_ALEN);
 
 	ra_list->total_pkts_size = 0;
-	ra_list->total_pkts = 0;
 
 	dev_dbg(adapter->dev, "info: allocated ra_list %p\n", ra_list);
 
@@ -648,7 +647,6 @@
 	skb_queue_tail(&ra_list->skb_head, skb);
 
 	ra_list->total_pkts_size += skb->len;
-	ra_list->total_pkts++;
 
 	atomic_inc(&priv->wmm.tx_pkts_queued);
 
@@ -975,6 +973,28 @@
 }
 
 /*
+ * This function checks if 11n aggregation is possible.
+ */
+static int
+mwifiex_is_11n_aggragation_possible(struct mwifiex_private *priv,
+				    struct mwifiex_ra_list_tbl *ptr,
+				    int max_buf_size)
+{
+	int count = 0, total_size = 0;
+	struct sk_buff *skb, *tmp;
+
+	skb_queue_walk_safe(&ptr->skb_head, skb, tmp) {
+		total_size += skb->len;
+		if (total_size >= max_buf_size)
+			break;
+		if (++count >= MIN_NUM_AMSDU)
+			return true;
+	}
+
+	return false;
+}
+
+/*
  * This function sends a single packet to firmware for transmission.
  */
 static void
@@ -1001,7 +1021,6 @@
 	dev_dbg(adapter->dev, "data: dequeuing the packet %p %p\n", ptr, skb);
 
 	ptr->total_pkts_size -= skb->len;
-	ptr->total_pkts--;
 
 	if (!skb_queue_empty(&ptr->skb_head))
 		skb_next = skb_peek(&ptr->skb_head);
@@ -1027,7 +1046,6 @@
 		skb_queue_tail(&ptr->skb_head, skb);
 
 		ptr->total_pkts_size += skb->len;
-		ptr->total_pkts++;
 		tx_info->flags |= MWIFIEX_BUF_FLAG_REQUEUED_PKT;
 		spin_unlock_irqrestore(&priv->wmm.ra_list_spinlock,
 				       ra_list_flags);
@@ -1213,11 +1231,9 @@
 				mwifiex_send_delba(priv, tid_del, ra, 1);
 			}
 		}
-/* Minimum number of AMSDU */
-#define MIN_NUM_AMSDU 2
-
 		if (mwifiex_is_amsdu_allowed(priv, tid) &&
-				(ptr->total_pkts >= MIN_NUM_AMSDU))
+		    mwifiex_is_11n_aggragation_possible(priv, ptr,
+							adapter->tx_buf_size))
 			mwifiex_11n_aggregate_pkt(priv, ptr, INTF_HEADER_LEN,
 						  ptr_index, flags);
 			/* ra_list_spinlock has been freed in