qcacld-3.0: Reduce lock held time

Currently we process and free the nbuf from
queue while holding a lock for the complete duration.
There might be a case when there are many packets pending
in the queue. This might cause the issue when we held the lock
and other process waits for lock.

So as part of the fix only perform the nbuf unlink inside the
lock and move the processing and free part outside the lock.

Change-Id: Iea0cabecc25ce90c189454b288421b1e720777f2
CRs-Fixed: 3125790

core/dp/txrx3.0/dp_rx_thread.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2014-2021 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -23,6 +24,7 @@
 #include <cdp_txrx_cmn_struct.h>
 #include <cdp_txrx_peer_ops.h>
 #include <cds_sched.h>
+#include "dp_rx.h"
 
 /* Timeout in ms to wait for a DP rx thread */
 #ifdef HAL_CONFIG_SLUB_DEBUG_ON
@@ -1060,21 +1062,34 @@ QDF_STATUS dp_rx_thread_flush_by_vdev_id(struct dp_rx_thread *rx_thread,
 	qdf_nbuf_t nbuf_list, tmp_nbuf_list;
 	uint32_t num_list_elements = 0;
 	QDF_STATUS qdf_status = QDF_STATUS_SUCCESS;
+	uint64_t lock_time, unlock_time;
+	qdf_nbuf_t nbuf_list_head = NULL, nbuf_list_next;
 
 	qdf_nbuf_queue_head_lock(&rx_thread->nbuf_queue);
+	lock_time = qdf_get_log_timestamp();
 	QDF_NBUF_QUEUE_WALK_SAFE(&rx_thread->nbuf_queue, nbuf_list,
 				 tmp_nbuf_list) {
 		if (QDF_NBUF_CB_RX_VDEV_ID(nbuf_list) == vdev_id) {
 			qdf_nbuf_unlink_no_lock(nbuf_list,
 						&rx_thread->nbuf_queue);
-			dp_rx_thread_adjust_nbuf_list(nbuf_list);
-			num_list_elements =
-				QDF_NBUF_CB_RX_NUM_ELEMENTS_IN_LIST(nbuf_list);
-			rx_thread->stats.rx_flushed += num_list_elements;
-			qdf_nbuf_list_free(nbuf_list);
+			DP_RX_HEAD_APPEND(nbuf_list_head, nbuf_list);
 		}
 	}
 	qdf_nbuf_queue_head_unlock(&rx_thread->nbuf_queue);
+	unlock_time = qdf_get_log_timestamp();
+	dp_info("Lock held time: %llu us",
+			qdf_log_timestamp_to_usecs(unlock_time - lock_time));
+
+	while (nbuf_list_head) {
+		nbuf_list_next = qdf_nbuf_queue_next(nbuf_list_head);
+		qdf_nbuf_set_next(nbuf_list_head, NULL);
+		dp_rx_thread_adjust_nbuf_list(nbuf_list_head);
+		num_list_elements =
+			QDF_NBUF_CB_RX_NUM_ELEMENTS_IN_LIST(nbuf_list_head);
+		rx_thread->stats.rx_flushed += num_list_elements;
+		qdf_nbuf_list_free(nbuf_list_head);
+		nbuf_list_head = nbuf_list_next;
+	}
 
 	qdf_event_reset(&rx_thread->vdev_del_event);
 	qdf_set_bit(RX_VDEV_DEL_EVENT, &rx_thread->event_flag);