qcacld-3.0: Avoid dsc wrapper in per-packet path

In OSIF every north bound entry is protected via dsc. DSC op start/stop
takes a spinlock for every call into the driver, the framework
also searches through a osif vdev list for every into driver call.

In per-packet path this is operation of taking/releasing the spinlocks
and traversal of the linked lists is costly. To avoid this and
protect the DP operations against SSR/load unload define a new
atomic variable. Before SSR/driver unload wait for the DP op
also to complete.

Change-Id: I4e9061b9e6b454b20789f9d7d3b7e3955a9bfaa5
CRs-Fixed: 3060552

core/hdd/inc/wlan_hdd_main.h

@@ -125,6 +125,13 @@
  * Preprocessor definitions and constants
  */
 
+static qdf_atomic_t dp_protect_entry_count;
+/* Milli seconds to delay SSR thread when an packet is getting processed */
+#define SSR_WAIT_SLEEP_TIME 200
+/* MAX iteration count to wait for dp tx to complete */
+#define MAX_SSR_WAIT_ITERATIONS 100
+#define MAX_SSR_PROTECT_LOG (16)
+
 #ifdef FEATURE_WLAN_APF
 /**
  * struct hdd_apf_context - hdd Context for apf
@@ -5048,4 +5055,23 @@ QDF_STATUS hdd_stop_adapter_ext(struct hdd_context *hdd_ctx,
  * released.
  */
 void hdd_check_for_net_dev_ref_leak(struct hdd_adapter *adapter);
+
+/**
+ * hdd_wait_for_dp_tx: Wait for packet tx to complete
+ *
+ * This function waits for dp packet tx to complete
+ *
+ * Return: None
+ */
+void hdd_wait_for_dp_tx(void);
+
+static inline void hdd_dp_ssr_protect(void)
+{
+	qdf_atomic_inc_return(&dp_protect_entry_count);
+}
+
+static inline void hdd_dp_ssr_unprotect(void)
+{
+	qdf_atomic_dec(&dp_protect_entry_count);
+}
 #endif /* end #if !defined(WLAN_HDD_MAIN_H) */

core/hdd/src/wlan_hdd_driver_ops.c

@@ -1031,6 +1031,7 @@ static void hdd_soc_recovery_shutdown(struct device *dev)
 	if (errno)
 		return;
 
+	hdd_wait_for_dp_tx();
 	osif_psoc_sync_wait_for_ops(psoc_sync);
 
 	__hdd_soc_recovery_shutdown();

core/hdd/src/wlan_hdd_main.c

@@ -9182,6 +9182,7 @@ void hdd_wlan_exit(struct hdd_context *hdd_ctx)
 
 	hdd_enter();
 
+	hdd_wait_for_dp_tx();
 	wlan_hdd_destroy_mib_stats_lock();
 	hdd_debugfs_ini_config_deinit(hdd_ctx);
 	hdd_debugfs_mws_coex_info_deinit(hdd_ctx);
@@ -19299,6 +19300,32 @@ out:
 	return ret;
 }
 
+void hdd_wait_for_dp_tx(void)
+{
+	int count = MAX_SSR_WAIT_ITERATIONS;
+	int r;
+
+	hdd_enter();
+
+	while (count) {
+		r = atomic_read(&dp_protect_entry_count);
+
+		if (!r)
+			break;
+
+		if (--count) {
+			hdd_err_rl("Waiting for Packet tx to complete: %d",
+				   count);
+			msleep(SSR_WAIT_SLEEP_TIME);
+		}
+	}
+
+	if (!count)
+		hdd_err("Timed-out waiting for packet tx");
+
+	hdd_exit();
+}
+
 static const struct kernel_param_ops pcie_gen_speed_ops = {
 	.set = pcie_set_gen_speed_handler,
 	.get = param_get_int,

core/hdd/src/wlan_hdd_softap_tx_rx.c

@@ -786,17 +786,11 @@ drop_pkt_accounting:
 netdev_tx_t hdd_softap_hard_start_xmit(struct sk_buff *skb,
 				       struct net_device *net_dev)
 {
-	struct osif_vdev_sync *vdev_sync;
-
-	if (osif_vdev_sync_op_start(net_dev, &vdev_sync)) {
-		hdd_debug_rl("Operation on net_dev is not permitted");
-		kfree_skb(skb);
-		return NETDEV_TX_OK;
-	}
+	hdd_dp_ssr_protect();
 
 	__hdd_softap_hard_start_xmit(skb, net_dev);
 
-	osif_vdev_sync_op_stop(vdev_sync);
+	hdd_dp_ssr_unprotect();
 
 	return NETDEV_TX_OK;
 }

core/hdd/src/wlan_hdd_tx_rx.c

@@ -1327,17 +1327,11 @@ drop_pkt_accounting:
  */
 netdev_tx_t hdd_hard_start_xmit(struct sk_buff *skb, struct net_device *net_dev)
 {
-	struct osif_vdev_sync *vdev_sync;
-
-	if (osif_vdev_sync_op_start(net_dev, &vdev_sync)) {
-		hdd_debug_rl("Operation on net_dev is not permitted");
-		kfree_skb(skb);
-		return NETDEV_TX_OK;
-	}
+	hdd_dp_ssr_protect();
 
 	__hdd_hard_start_xmit(skb, net_dev);
 
-	osif_vdev_sync_op_stop(vdev_sync);
+	hdd_dp_ssr_unprotect();
 
 	return NETDEV_TX_OK;
 }