net: ppp: Convert to use k_fifo instead of k_work

Following commits will remove k_work from net_pkt, so convert
PPP L2 to use k_fifo when sending PPP data.

Signed-off-by: Jukka Rissanen <[email protected]>

Author: jukkar

subsys/net/l2/ppp/Kconfig

@@ -92,4 +92,11 @@ config NET_L2_PPP_MGMT
 	  Enable support net_mgmt ppp interface which can be used to
 	  configure at run-time ppp drivers and L2 settings.
 
+config NET_L2_PPP_TX_STACK_SIZE
+	int "Stack size for TX handler"
+	default 2048 if COVERAGE_GCOV
+	default 1024
+	help
+	  Set the TX handler stack size.
+
 endif # NET_L2_PPP

subsys/net/l2/ppp/fsm.c

@@ -159,18 +159,6 @@ static void ppp_fsm_timeout(struct k_work *work)
 	}
 }
 
-static void ppp_pkt_send(struct k_work *work)
-{
-	struct net_pkt *pkt = CONTAINER_OF(work, struct net_pkt, work);
-	int ret;
-
-	ret = net_send_data(pkt);
-	if (ret < 0) {
-		net_pkt_unref(pkt);
-	}
-}
-
-
 void ppp_fsm_init(struct ppp_fsm *fsm, uint16_t protocol)
 {
 	fsm->protocol = protocol;
@@ -541,8 +529,7 @@ int ppp_send_pkt(struct ppp_fsm *fsm, struct net_if *iface,
 		 * have returned from this function. That is bad because the
 		 * fsm would be in wrong state and the received pkt is dropped.
 		 */
-		k_work_init(net_pkt_work(pkt), ppp_pkt_send);
-		k_work_submit(net_pkt_work(pkt));
+		ppp_queue_pkt(pkt);
 	} else {
 		ret = net_send_data(pkt);
 		if (ret < 0) {

subsys/net/l2/ppp/ppp_internal.h

@@ -101,6 +101,7 @@ int ppp_config_info_req(struct ppp_fsm *fsm,
 		.close = proto_close,					\
 	}
 
+void ppp_queue_pkt(struct net_pkt *pkt);
 const char *ppp_phase_str(enum ppp_phase phase);
 const char *ppp_state_str(enum ppp_state state);
 const char *ppp_proto2str(uint16_t proto);

subsys/net/l2/ppp/ppp_l2.c

@@ -21,6 +21,21 @@ LOG_MODULE_REGISTER(net_l2_ppp, CONFIG_NET_L2_PPP_LOG_LEVEL);
 #include "ppp_stats.h"
 #include "ppp_internal.h"
 
+static K_FIFO_DEFINE(tx_queue);
+
+#if IS_ENABLED(CONFIG_NET_TC_THREAD_COOPERATIVE)
+/* Lowest priority cooperative thread */
+#define THREAD_PRIORITY K_PRIO_COOP(CONFIG_NUM_COOP_PRIORITIES - 1)
+#else
+#define THREAD_PRIORITY K_PRIO_PREEMPT(CONFIG_NUM_PREEMPT_PRIORITIES - 1)
+#endif
+
+static void tx_handler(void);
+
+static K_THREAD_DEFINE(tx_handler_thread, CONFIG_NET_L2_PPP_TX_STACK_SIZE,
+		       (k_thread_entry_t)tx_handler, NULL, NULL, NULL,
+		       THREAD_PRIORITY, 0, 0);
+
 static const struct ppp_protocol_handler *ppp_lcp;
 
 static void ppp_update_rx_stats(struct net_if *iface,
@@ -429,6 +444,33 @@ static void ppp_startup(struct k_work *work)
 	}
 }
 
+void ppp_queue_pkt(struct net_pkt *pkt)
+{
+	k_fifo_put(&tx_queue, pkt);
+}
+
+static void tx_handler(void)
+{
+	struct net_pkt *pkt;
+	int ret;
+
+	NET_DBG("PPP TX started");
+
+	k_thread_name_set(NULL, "ppp_tx");
+
+	while (1) {
+		pkt = k_fifo_get(&tx_queue, K_FOREVER);
+		if (pkt == NULL) {
+			continue;
+		}
+
+		ret = net_send_data(pkt);
+		if (ret < 0) {
+			net_pkt_unref(pkt);
+		}
+	}
+}
+
 void net_ppp_init(struct net_if *iface)
 {
 	struct ppp_context *ctx = net_if_l2_data(iface);