net: buf: Redesigned pool & buffer allocation API

Until now it has been necessary to separately define a k_fifo and
an array of buffers when creating net_buf pools. This has been a bit
of an inconvenience as well as blurred the line of what exactly
constitutes the "pool".

This patch removes the NET_BUF_POOL() macro and replaces it with a
NET_BUF_POOL_DEFINE() macro that internally expands into the buffer
array and new net_buf_pool struct with a given name:

	NET_BUF_POOL_DEFINE(pool_name, ...);

Having a dedicated context struct for the pool has the added benefit
that we can start moving there net_buf members that have the same
value for all buffers from the same pool. The first such member that
gets moved is the destroy callback, thus shrinking net_buf by four
bytes. Another potential candidate is the user_data_size, however
right not that's left out since it would just leave 2 bytes of padding
in net_buf (i.e. not influence its size). Another common value is
buf->size, however that one is also used by net_buf_simple and can
therefore not be moved.

This patch also splits getting buffers from a FIFO and allocating a
new buffer from a pool into two separate APIs: net_buf_get and
net_buf_alloc, thus simplifying the APIs and their usage. There is no
separate 'reserve_head' parameter anymore when allocating, rather the
user is expected to call net_buf_reserve() afterwards if something
else than 0 headroom is desired.

Change-Id: Id91b1e5c2be2deb1274dde47f5edebfe29af383a
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

2 files changed, 18 insertions, 24 deletions

diff --git a/samples/bluetooth/hci_uart/src/main.c b/samples/bluetooth/hci_uart/src/main.c
index bf078e5f9..a9401719a 100644
--- a/samples/bluetooth/hci_uart/src/main.c
+++ b/samples/bluetooth/hci_uart/src/main.c
@@ -45,9 +45,8 @@ static BT_STACK_NOINIT(tx_thread_stack, CONFIG_BLUETOOTH_HCI_SEND_STACK);
 		      sizeof(struct bt_hci_cmd_hdr) + \
 		      CONFIG_BLUETOOTH_MAX_CMD_LEN)
 
-static struct k_fifo avail_cmd_tx;
-static NET_BUF_POOL(cmd_tx_pool, CONFIG_BLUETOOTH_HCI_CMD_COUNT, CMD_BUF_SIZE,
-		    &avail_cmd_tx, NULL, BT_BUF_USER_DATA_MIN);
+NET_BUF_POOL_DEFINE(cmd_tx_pool, CONFIG_BLUETOOTH_HCI_CMD_COUNT, CMD_BUF_SIZE,
+		    BT_BUF_USER_DATA_MIN, NULL);
 
 #define BT_L2CAP_MTU 64
 /** Data size needed for ACL buffers */
@@ -62,10 +61,8 @@ static NET_BUF_POOL(cmd_tx_pool, CONFIG_BLUETOOTH_HCI_CMD_COUNT, CMD_BUF_SIZE,
 #define TX_BUF_COUNT 6
 #endif
 
-static struct k_fifo avail_acl_tx;
-
-static NET_BUF_POOL(acl_tx_pool, TX_BUF_COUNT, BT_BUF_ACL_SIZE,
-		    &avail_acl_tx, NULL, BT_BUF_USER_DATA_MIN);
+NET_BUF_POOL_DEFINE(acl_tx_pool, TX_BUF_COUNT, BT_BUF_ACL_SIZE,
+		    BT_BUF_USER_DATA_MIN, NULL);
 
 static struct k_fifo tx_queue;
 
@@ -126,7 +123,7 @@ static struct net_buf *h4_cmd_recv(int *remaining)
 
 	*remaining = hdr.param_len;
 
-	buf = net_buf_get(&avail_cmd_tx, 0);
+	buf = net_buf_alloc(&cmd_tx_pool, K_NO_WAIT);
 	if (buf) {
 		bt_buf_set_type(buf, BT_BUF_CMD);
 		memcpy(net_buf_add(buf, sizeof(hdr)), &hdr, sizeof(hdr));
@@ -147,7 +144,7 @@ static struct net_buf *h4_acl_recv(int *remaining)
 	/* We can ignore the return value since we pass len == min */
 	h4_read(hci_uart_dev, (void *)&hdr, sizeof(hdr), sizeof(hdr));
 
-	buf = net_buf_get(&avail_acl_tx, 0);
+	buf = net_buf_alloc(&acl_tx_pool, K_NO_WAIT);
 	if (buf) {
 		bt_buf_set_type(buf, BT_BUF_ACL_OUT);
 		memcpy(net_buf_add(buf, sizeof(hdr)), &hdr, sizeof(hdr));
@@ -245,7 +242,7 @@ static void tx_thread(void *p1, void *p2, void *p3)
 		struct net_buf *buf;
 
 		/* Wait until a buffer is available */
-		buf = net_buf_get_timeout(&tx_queue, 0, K_FOREVER);
+		buf = net_buf_get(&tx_queue, K_FOREVER);
 		/* Pass buffer to the stack */
 		bt_send(buf);
 
@@ -362,8 +359,8 @@ void main(void)
 	SYS_LOG_DBG("Start");
 
 	/* Initialize the buffer pools */
-	net_buf_pool_init(cmd_tx_pool);
-	net_buf_pool_init(acl_tx_pool);
+	net_buf_pool_init(&cmd_tx_pool);
+	net_buf_pool_init(&acl_tx_pool);
 	/* Initialize the FIFOs */
 	k_fifo_init(&tx_queue);
 	k_fifo_init(&rx_queue);
@@ -379,7 +376,7 @@ void main(void)
 	while (1) {
 		struct net_buf *buf;
 
-		buf = net_buf_get_timeout(&rx_queue, 0, K_FOREVER);
+		buf = net_buf_get(&rx_queue, K_FOREVER);
 		err = h4_send(buf);
 		if (err) {
 			SYS_LOG_ERR("Failed to send");
diff --git a/samples/bluetooth/hci_usb/src/main.c b/samples/bluetooth/hci_usb/src/main.c
index 675f0923f..b6aca2f21 100644
--- a/samples/bluetooth/hci_usb/src/main.c
+++ b/samples/bluetooth/hci_usb/src/main.c
@@ -88,9 +88,8 @@ static struct k_fifo rx_queue;
 		      sizeof(struct bt_hci_cmd_hdr) + \
 		      CONFIG_BLUETOOTH_MAX_CMD_LEN)
 
-static struct k_fifo avail_tx;
-static NET_BUF_POOL(tx_pool, CONFIG_BLUETOOTH_HCI_CMD_COUNT, CMD_BUF_SIZE,
-		    &avail_tx, NULL, sizeof(uint8_t));
+NET_BUF_POOL_DEFINE(tx_pool, CONFIG_BLUETOOTH_HCI_CMD_COUNT, CMD_BUF_SIZE,
+		    sizeof(uint8_t), NULL);
 
 #define BT_L2CAP_MTU 64
 /** Data size needed for ACL buffers */
@@ -99,9 +98,7 @@ static NET_BUF_POOL(tx_pool, CONFIG_BLUETOOTH_HCI_CMD_COUNT, CMD_BUF_SIZE,
 			 4 /* L2CAP header size */ + \
 			 BT_L2CAP_MTU)
 
-static struct k_fifo avail_acl_tx;
-static NET_BUF_POOL(acl_tx_pool, 2, BT_BUF_ACL_SIZE, &avail_acl_tx, NULL,
-		    sizeof(uint8_t));
+NET_BUF_POOL_DEFINE(acl_tx_pool, 2, BT_BUF_ACL_SIZE, sizeof(uint8_t), NULL);
 
 /* Device data structure */
 struct btusb_dev_data_t {
@@ -447,7 +444,7 @@ static void btusb_bulk_out(uint8_t ep, enum usb_dc_ep_cb_status_code ep_status)
 		return;
 	}
 
-	buf = net_buf_get(&avail_acl_tx, 0);
+	buf = net_buf_alloc(&acl_tx_pool, K_NO_WAIT);
 	if (!buf) {
 		SYS_LOG_ERR("Cannot get free buffer\n");
 		return;
@@ -616,7 +613,7 @@ static int btusb_class_handler(struct usb_setup_packet *setup,
 
 	hexdump(">", *data, *len);
 
-	buf = net_buf_get(&avail_tx, 0);
+	buf = net_buf_alloc(&tx_pool, K_NO_WAIT);
 	if (!buf) {
 		SYS_LOG_ERR("Cannot get free buffer\n");
 		return -ENOMEM;
@@ -695,8 +692,8 @@ void main(void)
 	SYS_LOG_DBG("Start");
 
 	/* Initialize the buffer pools */
-	net_buf_pool_init(tx_pool);
-	net_buf_pool_init(acl_tx_pool);
+	net_buf_pool_init(&tx_pool);
+	net_buf_pool_init(&acl_tx_pool);
 	k_fifo_init(&rx_queue);
 
 	bt_enable_raw(&rx_queue);
@@ -704,7 +701,7 @@ void main(void)
 	while (1) {
 		struct net_buf *buf;
 
-		buf = net_buf_get_timeout(&rx_queue, 0, K_FOREVER);
+		buf = net_buf_get(&rx_queue, K_FOREVER);
 
 		hexdump("<", buf->data, buf->len);