Bluetooth: Controller: Fix ISO Tx ack data flow for context-safety

Fix ISO Tx ack data flow design for context-safety.

Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>

Author: cvinayak

subsys/bluetooth/controller/ll_sw/ull_iso.c

@@ -60,6 +60,7 @@
 #include "ull_sync_iso_internal.h"
 #include "ull_conn_iso_internal.h"
 
+#include "ll.h"
 #include "ll_feat.h"
 
 #include "hal/debug.h"
@@ -150,9 +151,6 @@ static void iso_rx_demux(void *param);
 #define ISO_TEST_PACKET_COUNTER_SIZE 4U
 
 #if defined(CONFIG_BT_CTLR_ADV_ISO) || defined(CONFIG_BT_CTLR_CONN_ISO)
-void ll_iso_link_tx_release(void *link);
-void ll_iso_tx_mem_release(void *node_tx);
-
 #define NODE_TX_BUFFER_SIZE MROUND(offsetof(struct node_tx_iso, pdu) + \
 				   offsetof(struct pdu_iso, payload) + \
 				   MAX(LL_BIS_OCTETS_TX_MAX, \
@@ -170,6 +168,10 @@ static struct {
 	uint8_t pool[sizeof(memq_link_t) * BT_CTLR_ISO_TX_PDU_BUFFERS];
 } mem_link_iso_tx;
 
+/* MFIFO for ISO TX acknowledgments from LLL to ULL */
+static MFIFO_DEFINE(iso_ack, sizeof(struct lll_tx), BT_CTLR_ISO_TX_PDU_BUFFERS);
+
+static void ull_iso_tx_ack_sched(void);
 #endif /* CONFIG_BT_CTLR_ADV_ISO || CONFIG_BT_CTLR_CONN_ISO */
 
 uint8_t ll_read_iso_tx_sync(uint16_t handle, uint16_t *seq,
@@ -1477,21 +1479,18 @@ void ull_iso_lll_ack_enqueue(uint16_t handle, struct node_tx_iso *node_tx)
 
 		if (dp) {
 			isoal_tx_pdu_release(dp->source_hdl, node_tx);
-		} else {
+			return;
+		}
+
 #if defined(CONFIG_BT_CTLR_ISO_VENDOR_DATA_PATH)
-			/* Possible race with Data Path remove - handle release in vendor
-			 * function.
-			 */
-			ll_data_path_tx_pdu_release(handle, node_tx);
+		/* Possible race with Data Path remove - handle release in vendor
+		 * function.
+		 */
+		ll_data_path_tx_pdu_release(handle, node_tx);
+		return;
 #else
-			/* FIXME: ll_tx_ack_put is not LLL callable as it is
-			 * used by ACL connections in ULL context to dispatch
-			 * ack.
-			 */
-			ll_tx_ack_put(handle, (void *)node_tx);
-			ll_rx_sched();
+		/* No datapath and no vendor datapath - fall through to MFIFO */
 #endif /* CONFIG_BT_CTLR_ISO_VENDOR_DATA_PATH */
-		}
 	} else if (IS_ENABLED(CONFIG_BT_CTLR_ADV_ISO) && IS_ADV_ISO_HANDLE(handle)) {
 		struct lll_adv_iso_stream *stream;
 		struct ll_iso_datapath *dp;
@@ -1502,25 +1501,38 @@ void ull_iso_lll_ack_enqueue(uint16_t handle, struct node_tx_iso *node_tx)
 		dp = stream->dp;
 
 		if (dp) {
+			/* Unified: Use ISOAL like CIS */
 			isoal_tx_pdu_release(dp->source_hdl, node_tx);
-		} else {
+			return;
+		}
+
 #if defined(CONFIG_BT_CTLR_ISO_VENDOR_DATA_PATH)
-			/* Possible race with Data Path remove - handle release in vendor
-			 * function.
-			 */
-			ll_data_path_tx_pdu_release(handle, node_tx);
+		ll_data_path_tx_pdu_release(handle, node_tx);
+		return;
 #else
-			/* FIXME: ll_tx_ack_put is not LLL callable as it is
-			 * used by ACL connections in ULL context to dispatch
-			 * ack.
-			 */
-			ll_tx_ack_put(handle, (void *)node_tx);
-			ll_rx_sched();
+		/* No datapath and no vendor datapath - fall through to MFIFO */
 #endif /* CONFIG_BT_CTLR_ISO_VENDOR_DATA_PATH */
-		}
 	} else {
 		LL_ASSERT_DBG(0);
+		return;
 	}
+
+	/* Context-safe fallback: Enqueue to iso_ack MFIFO when no datapath.
+	 * This handles CIS/BIS without datapath and without vendor data path support.
+	 */
+	struct lll_tx *lll_tx;
+	uint8_t idx;
+
+	idx = MFIFO_ENQUEUE_GET(iso_ack, (void **)&lll_tx);
+	LL_ASSERT_ERR(lll_tx);
+
+	lll_tx->handle = handle;
+	lll_tx->node = (struct node_tx *)node_tx;
+
+	MFIFO_ENQUEUE(iso_ack, idx);
+
+	/* Schedule independent ISO TX ack processing (not serialized with RX) */
+	ull_iso_tx_ack_sched();
 }
 
 void ull_iso_lll_event_prepare(uint16_t handle, uint64_t event_count)
@@ -1952,6 +1964,77 @@ static isoal_status_t ll_iso_pdu_release(struct node_tx_iso *node_tx,
 	return ISOAL_STATUS_OK;
 }
 #endif /* CONFIG_BT_CTLR_CONN_ISO */
+
+/**
+ * @brief Peek at next ISO TX ack without dequeuing
+ */
+static memq_link_t *ull_iso_ack_peek(uint8_t *ack_last, uint16_t *handle,
+				     struct node_tx_iso **tx)
+{
+	struct lll_tx *lll_tx;
+
+	lll_tx = MFIFO_DEQUEUE_GET(iso_ack);
+	if (!lll_tx) {
+		return NULL;
+	}
+
+	if (ack_last) {
+		*ack_last = mfifo_fifo_iso_ack.l;
+	}
+	*handle = lll_tx->handle;
+	*tx = (struct node_tx_iso *)lll_tx->node;
+
+	return (*tx)->link;
+}
+
+/**
+ * @brief Dequeue ISO TX ack from MFIFO
+ */
+static void *ull_iso_ack_dequeue(void)
+{
+	return MFIFO_DEQUEUE(iso_ack);
+}
+
+/**
+ * @brief Process ISO TX acknowledgments independently
+ * @details Processes iso_ack MFIFO without serialization with RX
+ */
+static void iso_tx_ack_demux(void *param)
+{
+	struct node_tx_iso *node_tx;
+	memq_link_t *link;
+	uint16_t handle;
+
+	/* Process all pending ISO TX acks */
+	do {
+		link = ull_iso_ack_peek(NULL, &handle, &node_tx);
+		if (link) {
+			/* Dequeue from iso_ack MFIFO */
+			ull_iso_ack_dequeue();
+
+			/* Now safely call ll_tx_ack_put in ULL context */
+			ll_tx_ack_put(handle, (struct node_tx *)node_tx);
+
+			/* Release link mem */
+			ll_iso_link_tx_release(link);
+		}
+	} while (link);
+
+	/* Trigger thread to call ll_rx_get() */
+	ll_rx_sched();
+}
+
+/**
+ * @brief Schedule ISO TX ack processing
+ */
+static void ull_iso_tx_ack_sched(void)
+{
+	static memq_link_t link;
+	static struct mayfly mfy = {0, 0, &link, NULL, iso_tx_ack_demux};
+
+	/* Kick the ULL (using the mayfly, tailchain it) */
+	mayfly_enqueue(TICKER_USER_ID_LLL, TICKER_USER_ID_ULL_HIGH, 1, &mfy);
+}
 #endif /* CONFIG_BT_CTLR_ADV_ISO || CONFIG_BT_CTLR_CONN_ISO */
 
 static int init_reset(void)
@@ -1988,6 +2071,9 @@ static int init_reset(void)
 	/* Initialize tx link pool. */
 	mem_init(mem_link_iso_tx.pool, sizeof(memq_link_t), BT_CTLR_ISO_TX_PDU_BUFFERS,
 		 &mem_link_iso_tx.free);
+
+	/* Initialize iso_ack MFIFO */
+	MFIFO_INIT(iso_ack);
 #endif /* CONFIG_BT_CTLR_ADV_ISO || CONFIG_BT_CTLR_CONN_ISO */
 
 #if BT_CTLR_ISO_STREAMS