From: Karthikeyan Periyasamy <periyasa@codeaurora.org>
Subject: [PATCH] ath11k: avoid RCU cpu stall

The following problems can result in RCU CPU stall warning
1. A CPU looping in an RCU read-side critical section
2. A CPU looping with interrupts disabled
3. A CPU looping with preemption disabled
4. A CPU looping with bottom halves disabled
scenario 1:
As per the above step 4, avoid spin_lock_bh() while
reporting low_ack to user.

scenario 2:
As per the above step 1 & 4, avoid rcu_read_lock() while
reporting mgmt rx through bottom halve disable call ieee80211_rx_ni()

Signed-off-by: Karthikeyan Periyasamy <periyasa@codeaurora.org>
---
--- a/drivers/net/wireless/ath/ath11k/wmi.c
+++ b/drivers/net/wireless/ath/ath11k/wmi.c
@@ -7429,6 +7429,7 @@ static void ath11k_mgmt_rx_event(struct
 	struct ieee80211_vif *vif;
 	struct ath11k_vif *arvif;
 	struct ath11k_mgmt_frame_stats *mgmt_stats;
+	struct ieee80211_hw *hw;
 	u16 frm_type = 0;
 
 	if (ath11k_pull_mgmt_rx_params_tlv(ab, skb, &rx_ev) != 0) {
@@ -7459,6 +7460,8 @@ static void ath11k_mgmt_rx_event(struct
 		goto exit;
 	}
 
+	hw = ar->hw;
+
 	if (rx_ev.status & WMI_RX_STATUS_ERR_MIC)
 		status->flag |= RX_FLAG_MMIC_ERROR;
 
@@ -7559,8 +7562,11 @@ skip_mgmt_stats:
 		   status->freq, status->band, status->signal,
 		   status->rate_idx);
 
-	ieee80211_rx_ni(ar->hw, skb);
+	rcu_read_unlock();
+
+	ieee80211_rx_ni(hw, skb);
 
+	return;
 exit:
 	rcu_read_unlock();
 }
@@ -7913,6 +7919,7 @@ static void ath11k_peer_sta_kickout_even
 	struct ieee80211_sta *sta;
 	struct ath11k_peer *peer;
 	struct ath11k *ar;
+	u32 vdev_id;
 
 	if (ath11k_pull_peer_sta_kickout_ev(ab, skb, &arg) != 0) {
 		ath11k_warn(ab, "failed to extract peer sta kickout event");
@@ -7926,15 +7933,20 @@ static void ath11k_peer_sta_kickout_even
 	peer = ath11k_peer_find_by_addr(ab, arg.mac_addr);
 
 	if (!peer) {
+		spin_unlock_bh(&ab->base_lock);
 		ath11k_warn(ab, "peer not found %pM\n",
 			    arg.mac_addr);
 		goto exit;
 	}
 
-	ar = ath11k_mac_get_ar_by_vdev_id(ab, peer->vdev_id);
+	vdev_id = peer->vdev_id;
+
+	spin_unlock_bh(&ab->base_lock);
+
+	ar = ath11k_mac_get_ar_by_vdev_id(ab, vdev_id);
 	if (!ar) {
 		ath11k_warn(ab, "invalid vdev id in peer sta kickout ev %d",
-			    peer->vdev_id);
+			    vdev_id);
 		goto exit;
 	}
 
@@ -7949,7 +7961,6 @@ static void ath11k_peer_sta_kickout_even
 	ieee80211_report_low_ack(sta, 10);
 
 exit:
-	spin_unlock_bh(&ab->base_lock);
 	rcu_read_unlock();
 }