qcacld-3.0: Reduce the threshold of drop in the intra-bss forwarding path

In case of intra-bss forwarding, tx-path consumes all the tx descriptors
and pause netif queues. As a result, there would be some left for stack
triggered packets such as ARP packets which leads to ref STA disconnection.
To avoid this, reserved a pool of descriptors(OL_TX_NON_FWD_RESERVE = 100)
for high priority packets such as ARP/EAPOL etc and drop the packets
to be forwarded in host itself.

CRs-Fixed: 1095203
Change-Id: I7d473118ef3d986f79aa5b7a47286235d7adcab4

core/dp/txrx/ol_rx_fwd.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2014-2016 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2011, 2014-2017 The Linux Foundation. All rights reserved.
  *
  * Previously licensed under the ISC license by Qualcomm Atheros, Inc.
  *
@@ -202,6 +202,21 @@ ol_rx_fwd_check(struct ol_txrx_vdev_t *vdev,
 				qdf_nbuf_set_tid(msdu,
 						 QDF_NBUF_TX_EXT_TID_INVALID);
 			}
+
+			if (!ol_txrx_fwd_desc_thresh_check(vdev)) {
+				/* Drop the packet*/
+				htt_rx_msdu_desc_free(pdev->htt_pdev, msdu);
+				qdf_net_buf_debug_release_skb(msdu);
+				TXRX_STATS_MSDU_LIST_INCR(
+					pdev, tx.dropped.host_reject, msdu);
+				/* add NULL terminator */
+				qdf_nbuf_set_next(msdu, NULL);
+				qdf_nbuf_tx_free(msdu,
+						 QDF_NBUF_PKT_ERROR);
+				msdu = msdu_list;
+				continue;
+			}
+
 			/*
 			 * This MSDU needs to be forwarded to the tx path.
 			 * Check whether it also needs to be sent to the OS
@@ -219,6 +234,7 @@ ol_rx_fwd_check(struct ol_txrx_vdev_t *vdev,
 					 pub.rx.intra_bss_fwd.packets_fwd, 1);
 			} else {
 				qdf_nbuf_t copy;
+
 				copy = qdf_nbuf_copy(msdu);
 				if (copy) {
 					ol_rx_fwd_to_tx(tx_vdev, copy);

core/dp/txrx/ol_txrx.c

@@ -4879,6 +4879,32 @@ ol_txrx_dump_pkt(qdf_nbuf_t nbuf, uint32_t nbuf_paddr, int len)
 		       qdf_nbuf_data(nbuf), len, true);
 }
 
+#ifdef QCA_LL_TX_FLOW_CONTROL_V2
+bool
+ol_txrx_fwd_desc_thresh_check(struct ol_txrx_vdev_t *vdev)
+{
+	struct ol_tx_flow_pool_t *pool = vdev->pool;
+	bool enough_desc_flag;
+
+	if (!vdev)
+		return true;
+
+	pool = vdev->pool;
+
+	qdf_spin_lock_bh(&pool->flow_pool_lock);
+	enough_desc_flag = (pool->avail_desc < (pool->stop_th +
+						OL_TX_NON_FWD_RESERVE))
+			   ? false : true;
+	qdf_spin_unlock_bh(&pool->flow_pool_lock);
+	return enough_desc_flag;
+}
+#else
+bool ol_txrx_fwd_desc_thresh_check(struct ol_txrx_vdev_t *vdev)
+{
+	return true;
+}
+#endif
+
 /**
  * ol_txrx_get_vdev_from_vdev_id() - get vdev from vdev_id
  * @vdev_id: vdev_id

core/dp/txrx/ol_txrx.h

@@ -31,6 +31,14 @@
 #include <qdf_nbuf.h>           /* qdf_nbuf_t */
 #include <cdp_txrx_cmn.h>       /* ol_txrx_vdev_t, etc. */
 #include "cds_sched.h"
+#include <ol_txrx_types.h>
+/*
+ * Pool of tx descriptors reserved for
+ * high-priority traffic, such as ARP/EAPOL etc
+ * only for forwarding path.
+ */
+#define OL_TX_NON_FWD_RESERVE	100
+
 
 void ol_txrx_peer_unref_delete(struct ol_txrx_peer_t *peer);
 
@@ -89,6 +97,26 @@ ol_txrx_hl_tdls_flag_reset(void *vdev, bool flag)
 void
 ol_txrx_dump_pkt(qdf_nbuf_t nbuf, uint32_t nbuf_paddr, int len);
 
+/**
+ * ol_txrx_fwd_desc_thresh_check() - check to forward packet to tx path
+ * @vdev: which virtual device the frames were addressed to
+ *
+ * This API is to check whether enough descriptors are available or not
+ * to forward packet to tx path. If not enough descriptors left,
+ * start dropping tx-path packets.
+ * Do not pause netif queues as still a pool of descriptors is reserved
+ * for high-priority traffic such as EAPOL/ARP etc.
+ * In case of intra-bss forwarding, it could be possible that tx-path can
+ * consume all the tx descriptors and pause netif queues. Due to this,
+ * there would be some left for stack triggered packets such as ARP packets
+ * which could lead to disconnection of device. To avoid this, reserved
+ * a pool of descriptors for high-priority packets, i.e., reduce the
+ * threshold of drop in the intra-bss forwarding path.
+ *
+ * Return: true ; forward the packet, i.e., below threshold
+ *         false; not enough descriptors, drop the packet
+ */
+bool ol_txrx_fwd_desc_thresh_check(struct ol_txrx_vdev_t *vdev);
 
 void *ol_txrx_get_vdev_from_vdev_id(uint8_t vdev_id);
 

core/hdd/src/wlan_hdd_ipa.c

@@ -48,6 +48,7 @@
 #include <linux/inetdevice.h>
 #include <linux/ip.h>
 #include <wlan_hdd_softap_tx_rx.h>
+#include <ol_txrx.h>
 #include <cdp_txrx_peer_ops.h>
 
 #include "cds_sched.h"
@@ -3221,6 +3222,14 @@ static enum hdd_ipa_forward_type hdd_ipa_intrabss_forward(
 	int ret = HDD_IPA_FORWARD_PKT_NONE;
 
 	if ((desc & FW_RX_DESC_FORWARD_M)) {
+		if (!ol_txrx_fwd_desc_thresh_check(
+			ol_txrx_get_vdev_from_vdev_id(adapter->sessionId))) {
+			/* Drop the packet*/
+			hdd_ipa->stats.num_tx_fwd_err++;
+			kfree_skb(skb);
+			ret = HDD_IPA_FORWARD_PKT_DISCARD;
+			return ret;
+		}
 		HDD_IPA_LOG(QDF_TRACE_LEVEL_DEBUG,
 				"Forward packet to Tx (fw_desc=%d)", desc);
 		hdd_ipa->ipa_tx_forward++;