qcacld-3.0: Fix deadlock scenario in packet capture mode

Ppdu_stats are received from firmware in softirq context.
While inserting the ppdu_stats into a qdf list, a spinlock
is held for its access, same qdf list is accessed by mon
thread using spinlock. There can be a scenario in which
mon_thread held spinlock for accessing qdf_list and is
interrupted by softirq in which ppdu_stats are received.
This leads to softirq spinning for lock forever leading
to deadlock.

To address this issue, use spin_lock_bh instead of spin_lock.
Also reduce the time for which lock is taken to access the list
for insertion and removal of ppdu_stats.

Change-Id: I52171fe3c1d22a1e9d1ab36daac54d8fa2b96020
CRs-Fixed: 3136901

components/pkt_capture/core/src/wlan_pkt_capture_data_txrx.c

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2020-2021 The Linux Foundation. All rights reserved.
- * Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.
+ * Copyright (c) 2021-2022 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
@@ -300,9 +300,10 @@ pkt_capture_update_tx_status(
 	pktcapture_hdr->nss = vdev_priv->tx_nss;
 
 	/* Remove the ppdu stats from front of list and fill it in tx_status */
-	qdf_spin_lock(&vdev_priv->lock_q);
+	qdf_spin_lock_bh(&vdev_priv->lock_q);
 	if (QDF_STATUS_SUCCESS ==
 	    qdf_list_remove_front(&vdev_priv->ppdu_stats_q, &node)) {
+		qdf_spin_unlock_bh(&vdev_priv->lock_q);
 		q_node = qdf_container_of(
 			node, struct pkt_capture_ppdu_stats_q_node, node);
 		smu = (htt_ppdu_stats_for_smu_tlv *)(q_node->buf);
@@ -318,8 +319,9 @@ pkt_capture_update_tx_status(
 				     2 * sizeof(uint32_t));
 
 		qdf_mem_free(q_node);
+	} else {
+		qdf_spin_unlock_bh(&vdev_priv->lock_q);
 	}
-	qdf_spin_unlock(&vdev_priv->lock_q);
 
 skip_ppdu_stats:
 	pkt_capture_tx_get_phy_info(pktcapture_hdr, tx_status);

components/pkt_capture/core/src/wlan_pkt_capture_main.c

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2020-2021 The Linux Foundation. All rights reserved.
- * Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.
+ * Copyright (c) 2021-2022 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
@@ -227,15 +227,15 @@ pkt_capture_process_ppdu_stats(void *log_data)
 	smu = (htt_ppdu_stats_for_smu_tlv *)log_data;
 	vdev_priv->tx_nss = smu->nss;
 
-	qdf_spin_lock(&vdev_priv->lock_q);
+	qdf_spin_lock_bh(&vdev_priv->lock_q);
 	if (qdf_list_size(&vdev_priv->ppdu_stats_q) <
 					PPDU_STATS_Q_MAX_SIZE) {
+		qdf_spin_unlock_bh(&vdev_priv->lock_q);
 		/*
 		 * win size indicates the size of block ack bitmap, currently
 		 * we support only 256 bit ba bitmap.
 		 */
 		if (smu->win_size > 8) {
-			qdf_spin_unlock(&vdev_priv->lock_q);
 			pkt_capture_vdev_put_ref(vdev);
 			pkt_capture_err("win size %d > 8 not supported\n",
 					smu->win_size);
@@ -247,7 +247,6 @@ pkt_capture_process_ppdu_stats(void *log_data)
 
 		q_node = qdf_mem_malloc(sizeof(*q_node) + stats_len);
 		if (!q_node) {
-			qdf_spin_unlock(&vdev_priv->lock_q);
 			pkt_capture_vdev_put_ref(vdev);
 			pkt_capture_err("stats node and buf allocation fail\n");
 			return;
@@ -255,10 +254,11 @@ pkt_capture_process_ppdu_stats(void *log_data)
 
 		qdf_mem_copy(q_node->buf, log_data, stats_len);
 		/* Insert received ppdu stats in queue */
+		qdf_spin_lock_bh(&vdev_priv->lock_q);
 		qdf_list_insert_back(&vdev_priv->ppdu_stats_q,
 				     &q_node->node);
 	}
-	qdf_spin_unlock(&vdev_priv->lock_q);
+	qdf_spin_unlock_bh(&vdev_priv->lock_q);
 	pkt_capture_vdev_put_ref(vdev);
 }