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implemented fix to prevent queue overfill #343

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e9076c3
implemented fix to prevent queue overfill
Aug 26, 2026
3796738
fixed trailing space
Aug 26, 2026
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51 changes: 45 additions & 6 deletions examples/firewall/net_components/firewall_network_virt_tx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,10 @@ net_queue_handle_t tx_queue_clients[SDDF_NET_MAX_CLIENTS];
fw_queue_t fw_free_clients[FW_MAX_FW_CLIENTS];
fw_queue_t fw_active_clients[FW_MAX_FW_CLIENTS];

/* Alternates which of the net/fw client groups tx_provide() will serve first, to
prevent starvation on tx_queue_drv. */
bool fw_clients_priority = false;

static int extract_offset_net_client(uintptr_t *phys)
{
for (int client = 0; client < config.num_clients; client++) {
Expand All @@ -48,13 +52,19 @@ static int extract_offset_fw_client(uintptr_t *phys)
return -1;
}

static void tx_provide(void)
/* sdfgen sizes tx_queue_drv for the net clients only, not the firewall
clients also feeding it, so fullness must be checked before every enqueue. */
static void tx_provide_net_clients(bool *enqueued, bool *drv_full)
{
bool enqueued = false;
for (int client = 0; client < config.num_clients; client++) {
for (int client = 0; client < config.num_clients && !*drv_full; client++) {
bool reprocess = true;
while (reprocess) {
while (!net_queue_empty_active(&tx_queue_clients[client])) {
if (net_queue_full_active(&tx_queue_drv)) {
*drv_full = true;
break;
}

net_buff_desc_t buffer;
int err = net_dequeue_active(&tx_queue_clients[client], &buffer);
assert(!err);
Expand All @@ -75,7 +85,11 @@ static void tx_provide(void)

err = net_enqueue_active(&tx_queue_drv, buffer);
assert(!err);
enqueued = true;
*enqueued = true;
}

if (*drv_full) {
break;
}

net_request_signal_active(&tx_queue_clients[client]);
Expand All @@ -87,9 +101,19 @@ static void tx_provide(void)
}
}
}
}

for (int client = 0; client < fw_config.num_active_clients; client++) {
static void tx_provide_fw_clients(bool *enqueued, bool *drv_full)
{
for (int client = 0; client < fw_config.num_active_clients && !*drv_full; client++) {
while (!fw_queue_empty(&fw_active_clients[client])) {
if (net_queue_full_active(&tx_queue_drv)) {
/* Leave remaining buffers queued rather than dropping them;
picked up on the next tx_provide() once tx_return() frees space. */
*drv_full = true;
break;
}

fw_buff_desc_t buffer;
int err = fw_dequeue(&fw_active_clients[client], &buffer);
assert(!err);
Expand All @@ -105,9 +129,24 @@ static void tx_provide(void)
net_buff_desc_t net_buffer = { .io_or_offset = io_addr, .len = buffer.len };
err = net_enqueue_active(&tx_queue_drv, net_buffer);
assert(!err);
enqueued = true;
*enqueued = true;
}
}
}

static void tx_provide(void)
{
bool enqueued = false;
bool drv_full = false;

if (fw_clients_priority) {
tx_provide_fw_clients(&enqueued, &drv_full);
tx_provide_net_clients(&enqueued, &drv_full);
} else {
tx_provide_net_clients(&enqueued, &drv_full);
tx_provide_fw_clients(&enqueued, &drv_full);
}
fw_clients_priority = !fw_clients_priority;

if (enqueued && net_require_signal_active(&tx_queue_drv)) {
net_cancel_signal_active(&tx_queue_drv);
Expand Down
35 changes: 32 additions & 3 deletions examples/firewall/routing/routing.c
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Original file line number Diff line number Diff line change
Expand Up @@ -79,8 +79,20 @@ static bool enqueue_icmp_unreachable(fw_buff_desc_t buffer, uint32_t next_hop)
return enqueued;
}

static void transmit_packet(fw_buff_desc_t buffer, uint8_t *mac_addr, uint8_t out_interface)
static void drop_buffer(fw_buff_desc_t buffer)
{
net_buff_desc_t net_buff = { .io_or_offset = buffer.offset, .len = buffer.len };
int err = fw_enqueue(&rx_free[buffer.interface], &net_buff);
assert(!err);
returned[buffer.interface] = true;
}

static bool transmit_packet(fw_buff_desc_t buffer, uint8_t *mac_addr, uint8_t out_interface)
{
if (fw_queue_full(&tx_active[out_interface])) {
return false;
}

uintptr_t pkt_vaddr = data_vaddr[buffer.interface] + buffer.offset;
eth_hdr_t *eth_hdr = (eth_hdr_t *)pkt_vaddr;
ipv4_hdr_t *ip_hdr = (ipv4_hdr_t *)(pkt_vaddr + IPV4_HDR_OFFSET);
Expand All @@ -103,6 +115,7 @@ static void transmit_packet(fw_buff_desc_t buffer, uint8_t *mac_addr, uint8_t ou
int err = fw_enqueue(&tx_active[out_interface], &buffer);
assert(!err);
tx_net[out_interface] = true;
return true;
}

static void process_arp_waiting(uint8_t out_interface)
Expand Down Expand Up @@ -143,7 +156,11 @@ static void process_arp_waiting(uint8_t out_interface)
/* Substitute the MAC address and send packets out of the NIC */
pkt_waiting_node_t *node = root;
for (uint16_t i = 0; i < root->num_children + 1; i++) {
transmit_packet(node->buffer, response.mac_addr, out_interface);
bool sent = transmit_packet(node->buffer, response.mac_addr, out_interface);
if (!sent) {
LOG_FIREWALL("ROUTING", "tx queue for interface %u full, dropping packet\n", out_interface);
drop_buffer(node->buffer);
}
node = pkts_waiting_next_child(&pkt_waiting_queue[out_interface], node);
}
}
Expand Down Expand Up @@ -196,6 +213,14 @@ static void route(void)
/* Check for webserver traffic */
tcp_hdr_t *tcp_pkt = (tcp_hdr_t *)(pkt_vaddr + transport_layer_offset(ip_hdr));
if (ip_hdr->protocol == IPV4_PROTO_TCP && tcp_pkt->dst_port == htons(WEBSERVER_PORT)) {
if (fw_queue_full(&webserver)) {
/* Webserver queue can receive buffers from any interface */
LOG_FIREWALL("ROUTING", "webserver queue full, dropping packet from interface %u\n",
interface);
drop_buffer(fw_buffer);
continue;
}

err = fw_enqueue(&webserver, &fw_buffer);
assert(!err);
tx_webserver = true;
Expand Down Expand Up @@ -303,7 +328,11 @@ static void route(void)
}

/* valid arp entry found, transmit packet */
transmit_packet(fw_buffer, arp->mac_addr, out_interface);
bool sent = transmit_packet(fw_buffer, arp->mac_addr, out_interface);
if (!sent) {
LOG_FIREWALL("ROUTING", "tx queue for interface %u full, dropping packet\n", out_interface);
drop_buffer(fw_buffer);
}
}
}
}
Expand Down
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