wifi: ath12k: Avoid CPU busy-wait by handling VDEV_STAT and BCN_STAT

When the ath12k driver is built without CONFIG_ATH12K_DEBUG, the
recently refactored stats code can cause any user space application
(such at NetworkManager) to consume 100% CPU for 3 seconds, every time
stats are read.

Commit 'b8a0d83fe4c7 ("wifi: ath12k: move firmware stats out of
debugfs")' moved ath12k_debugfs_fw_stats_request() out of debugfs, by
merging the additional logic into ath12k_mac_get_fw_stats().

Among the added responsibility of ath12k_mac_get_fw_stats() was the
busy-wait for `fw_stats_done`.

Signalling of `fw_stats_done` happens when one of the
WMI_REQUEST_PDEV_STAT, WMI_REQUEST_VDEV_STAT, and WMI_REQUEST_BCN_STAT
messages are received, but the handling of the latter two commands remained
in the debugfs code. As `fw_stats_done` isn't signalled, the calling
processes will spin until the timeout (3 seconds) is reached.

Moving the handling of these two additional responses out of debugfs
resolves the issue.

Fixes: b8a0d83 ("wifi: ath12k: move firmware stats out of debugfs")
Signed-off-by: Bjorn Andersson <[email protected]>
Tested-by: Abel Vesa <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jeff Johnson <[email protected]>

Author: quic-bjorande

drivers/net/wireless/ath/ath12k/debugfs.c

@@ -1251,64 +1251,6 @@ void ath12k_debugfs_soc_destroy(struct ath12k_base *ab)
 	 */
 }
 
-void
-ath12k_debugfs_fw_stats_process(struct ath12k *ar,
-				struct ath12k_fw_stats *stats)
-{
-	struct ath12k_base *ab = ar->ab;
-	struct ath12k_pdev *pdev;
-	bool is_end;
-	static unsigned int num_vdev, num_bcn;
-	size_t total_vdevs_started = 0;
-	int i;
-
-	if (stats->stats_id == WMI_REQUEST_VDEV_STAT) {
-		if (list_empty(&stats->vdevs)) {
-			ath12k_warn(ab, "empty vdev stats");
-			return;
-		}
-		/* FW sends all the active VDEV stats irrespective of PDEV,
-		 * hence limit until the count of all VDEVs started
-		 */
-		rcu_read_lock();
-		for (i = 0; i < ab->num_radios; i++) {
-			pdev = rcu_dereference(ab->pdevs_active[i]);
-			if (pdev && pdev->ar)
-				total_vdevs_started += pdev->ar->num_started_vdevs;
-		}
-		rcu_read_unlock();
-
-		is_end = ((++num_vdev) == total_vdevs_started);
-
-		list_splice_tail_init(&stats->vdevs,
-				      &ar->fw_stats.vdevs);
-
-		if (is_end) {
-			ar->fw_stats.fw_stats_done = true;
-			num_vdev = 0;
-		}
-		return;
-	}
-	if (stats->stats_id == WMI_REQUEST_BCN_STAT) {
-		if (list_empty(&stats->bcn)) {
-			ath12k_warn(ab, "empty beacon stats");
-			return;
-		}
-		/* Mark end until we reached the count of all started VDEVs
-		 * within the PDEV
-		 */
-		is_end = ((++num_bcn) == ar->num_started_vdevs);
-
-		list_splice_tail_init(&stats->bcn,
-				      &ar->fw_stats.bcn);
-
-		if (is_end) {
-			ar->fw_stats.fw_stats_done = true;
-			num_bcn = 0;
-		}
-	}
-}
-
 static int ath12k_open_vdev_stats(struct inode *inode, struct file *file)
 {
 	struct ath12k *ar = inode->i_private;

drivers/net/wireless/ath/ath12k/debugfs.h

@@ -12,8 +12,6 @@ void ath12k_debugfs_soc_create(struct ath12k_base *ab);
 void ath12k_debugfs_soc_destroy(struct ath12k_base *ab);
 void ath12k_debugfs_register(struct ath12k *ar);
 void ath12k_debugfs_unregister(struct ath12k *ar);
-void ath12k_debugfs_fw_stats_process(struct ath12k *ar,
-				     struct ath12k_fw_stats *stats);
 void ath12k_debugfs_op_vif_add(struct ieee80211_hw *hw,
 			       struct ieee80211_vif *vif);
 void ath12k_debugfs_pdev_create(struct ath12k_base *ab);
@@ -126,11 +124,6 @@ static inline void ath12k_debugfs_unregister(struct ath12k *ar)
 {
 }
 
-static inline void ath12k_debugfs_fw_stats_process(struct ath12k *ar,
-						   struct ath12k_fw_stats *stats)
-{
-}
-
 static inline bool ath12k_debugfs_is_extd_rx_stats_enabled(struct ath12k *ar)
 {
 	return false;

drivers/net/wireless/ath/ath12k/wmi.c

@@ -7626,6 +7626,63 @@ static int ath12k_wmi_pull_fw_stats(struct ath12k_base *ab, struct sk_buff *skb,
 				   &parse);
 }
 
+static void ath12k_wmi_fw_stats_process(struct ath12k *ar,
+					struct ath12k_fw_stats *stats)
+{
+	struct ath12k_base *ab = ar->ab;
+	struct ath12k_pdev *pdev;
+	bool is_end;
+	static unsigned int num_vdev, num_bcn;
+	size_t total_vdevs_started = 0;
+	int i;
+
+	if (stats->stats_id == WMI_REQUEST_VDEV_STAT) {
+		if (list_empty(&stats->vdevs)) {
+			ath12k_warn(ab, "empty vdev stats");
+			return;
+		}
+		/* FW sends all the active VDEV stats irrespective of PDEV,
+		 * hence limit until the count of all VDEVs started
+		 */
+		rcu_read_lock();
+		for (i = 0; i < ab->num_radios; i++) {
+			pdev = rcu_dereference(ab->pdevs_active[i]);
+			if (pdev && pdev->ar)
+				total_vdevs_started += pdev->ar->num_started_vdevs;
+		}
+		rcu_read_unlock();
+
+		is_end = ((++num_vdev) == total_vdevs_started);
+
+		list_splice_tail_init(&stats->vdevs,
+				      &ar->fw_stats.vdevs);
+
+		if (is_end) {
+			ar->fw_stats.fw_stats_done = true;
+			num_vdev = 0;
+		}
+		return;
+	}
+	if (stats->stats_id == WMI_REQUEST_BCN_STAT) {
+		if (list_empty(&stats->bcn)) {
+			ath12k_warn(ab, "empty beacon stats");
+			return;
+		}
+		/* Mark end until we reached the count of all started VDEVs
+		 * within the PDEV
+		 */
+		is_end = ((++num_bcn) == ar->num_started_vdevs);
+
+		list_splice_tail_init(&stats->bcn,
+				      &ar->fw_stats.bcn);
+
+		if (is_end) {
+			ar->fw_stats.fw_stats_done = true;
+			num_bcn = 0;
+		}
+	}
+}
+
 static void ath12k_update_stats_event(struct ath12k_base *ab, struct sk_buff *skb)
 {
 	struct ath12k_fw_stats stats = {};
@@ -7655,19 +7712,15 @@ static void ath12k_update_stats_event(struct ath12k_base *ab, struct sk_buff *sk
 
 	spin_lock_bh(&ar->data_lock);
 
-	/* WMI_REQUEST_PDEV_STAT can be requested via .get_txpower mac ops or via
-	 * debugfs fw stats. Therefore, processing it separately.
-	 */
+	/* Handle WMI_REQUEST_PDEV_STAT status update */
 	if (stats.stats_id == WMI_REQUEST_PDEV_STAT) {
 		list_splice_tail_init(&stats.pdevs, &ar->fw_stats.pdevs);
 		ar->fw_stats.fw_stats_done = true;
 		goto complete;
 	}
 
-	/* WMI_REQUEST_VDEV_STAT and WMI_REQUEST_BCN_STAT are currently requested only
-	 * via debugfs fw stats. Hence, processing these in debugfs context.
-	 */
-	ath12k_debugfs_fw_stats_process(ar, &stats);
+	/* Handle WMI_REQUEST_VDEV_STAT and WMI_REQUEST_BCN_STAT updates. */
+	ath12k_wmi_fw_stats_process(ar, &stats);
 
 complete:
 	complete(&ar->fw_stats_complete);