Bluetooth: ATT: Remove BT_ATT_TX_MAX

ATT channels do support queueing buffer so it no longer need to block
waiting the tx_sem besides the buffer allocation already serves the
same purpose as the application will not be able to have more requests
than there are buffers available.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

subsys/bluetooth/host/Kconfig.gatt

@@ -24,16 +24,6 @@ config BT_ATT_PREPARE_COUNT
 	  Number of buffers available for ATT prepare write, setting
 	  this to 0 disables GATT long/reliable writes.
 
-config BT_ATT_TX_MAX
-	int "Maximum number of queued outgoing ATT PDUs"
-	default BT_L2CAP_TX_BUF_COUNT
-	range 1 BT_L2CAP_TX_BUF_COUNT
-	help
-	  Number of ATT PDUs that can be at a single moment queued for
-	  transmission. If the application tries to send more than this
-	  amount the calls will block until an existing queued PDU gets
-	  sent.
-
 config BT_EATT
 	bool "Enhanced ATT Bearers support [EXPERIMENTAL]"
 	depends on BT_L2CAP_ECRED

subsys/bluetooth/host/att.c

@@ -66,7 +66,7 @@ NET_BUF_POOL_DEFINE(prep_pool, CONFIG_BT_ATT_PREPARE_COUNT, BT_ATT_MTU,
 #endif /* CONFIG_BT_ATT_PREPARE_COUNT */
 
 K_MEM_SLAB_DEFINE(req_slab, sizeof(struct bt_att_req),
-		  CONFIG_BT_ATT_TX_MAX, __alignof__(struct bt_att_req));
+		  CONFIG_BT_L2CAP_TX_BUF_COUNT, __alignof__(struct bt_att_req));
 
 enum {
 	ATT_PENDING_RSP,
@@ -88,7 +88,6 @@ struct bt_att_chan {
 	struct bt_att_req	*req;
 	struct k_fifo		tx_queue;
 	struct k_delayed_work	timeout_work;
-	struct k_sem            tx_sem;
 	void (*sent)(struct bt_att_chan *chan);
 	sys_snode_t		node;
 };
@@ -315,12 +314,7 @@ static void bt_att_sent(struct bt_l2cap_chan *ch)
 	}
 
 	/* Process global queue */
-	err = process_queue(chan, &att->tx_queue);
-	if (!err) {
-		return;
-	}
-
-	k_sem_give(&chan->tx_sem);
+	(void)process_queue(chan, &att->tx_queue);
 }
 
 static void chan_cfm_sent(struct bt_att_chan *chan)
@@ -464,13 +458,6 @@ static int bt_att_chan_send(struct bt_att_chan *chan, struct net_buf *buf,
 	BT_DBG("chan %p flags %u code 0x%02x", chan, atomic_get(chan->flags),
 	       hdr->code);
 
-	/* Don't use tx_sem if caller has set it own callback */
-	if (!cb) {
-		if (k_sem_take(&chan->tx_sem, K_NO_WAIT) < 0) {
-			return -EAGAIN;
-		}
-	}
-
 	return chan_send(chan, buf, cb);
 }
 
@@ -565,8 +552,6 @@ static uint8_t att_mtu_req(struct bt_att_chan *chan, struct net_buf *buf)
 static int bt_att_chan_req_send(struct bt_att_chan *chan,
 				struct bt_att_req *req)
 {
-	int err;
-
 	__ASSERT_NO_MSG(chan);
 	__ASSERT_NO_MSG(req);
 	__ASSERT_NO_MSG(req->func);
@@ -574,16 +559,7 @@ static int bt_att_chan_req_send(struct bt_att_chan *chan,
 
 	BT_DBG("req %p", req);
 
-	if (k_sem_take(&chan->tx_sem, K_NO_WAIT) < 0) {
-		return -EAGAIN;
-	}
-
-	err = chan_req_send(chan, req);
-	if (err < 0) {
-		k_sem_give(&chan->tx_sem);
-	}
-
-	return err;
+	return chan_req_send(chan, req);
 }
 
 static void att_process(struct bt_att *att)
@@ -2567,17 +2543,11 @@ static void att_reset(struct bt_att *att)
 static void att_chan_detach(struct bt_att_chan *chan)
 {
 	struct net_buf *buf;
-	int i;
 
 	BT_DBG("chan %p", chan);
 
 	sys_slist_find_and_remove(&chan->att->chans, &chan->node);
 
-	/* Ensure that any waiters are woken up */
-	for (i = 0; i < CONFIG_BT_ATT_TX_MAX; i++) {
-		k_sem_give(&chan->tx_sem);
-	}
-
 	/* Release pending buffers */
 	while ((buf = net_buf_get(&chan->tx_queue, K_NO_WAIT))) {
 		net_buf_unref(buf);
@@ -2811,7 +2781,6 @@ static struct bt_att_chan *att_chan_new(struct bt_att *att, atomic_val_t flags)
 	(void)memset(chan, 0, sizeof(*chan));
 	chan->chan.chan.ops = &ops;
 	k_fifo_init(&chan->tx_queue);
-	k_sem_init(&chan->tx_sem, CONFIG_BT_ATT_TX_MAX, CONFIG_BT_ATT_TX_MAX);
 	atomic_set(chan->flags, flags);
 	chan->att = att;
 

tests/bluetooth/bsim_bt/edtt_ble_test_app/gatt_test_app/prj.conf

@@ -7,7 +7,6 @@ CONFIG_BT_SIGNING=y
 CONFIG_BT_TINYCRYPT_ECC=y
 CONFIG_BT_PERIPHERAL=y
 CONFIG_BT_ATT_PREPARE_COUNT=2
-CONFIG_BT_ATT_TX_MAX=3
 CONFIG_BT_PRIVACY=y
 CONFIG_BT_DEVICE_NAME="Test Database"
 CONFIG_BT_DEVICE_APPEARANCE=833