virtionet: Fix a few issues with sendq

src/drivers/virtionet.cpp

@@ -265,9 +265,9 @@ void VirtioNet::msix_xmit_handler()
   while (tx_q.new_incoming())
   {
     auto res = tx_q.dequeue();
-    // get packet offset, and call destructor
-    auto* packet = (net::Packet*) (res.data() - sizeof(net::Packet));
-    delete packet; // call deleter on Packet to release it
+    assert(res.data() != nullptr);
+    // get packet offset, and call placement Packet deleter directly
+    net::Packet::operator delete(res.data() - sizeof(net::Packet));
     dequeued_tx++;
   }
   tx_q.enable_interrupts();
@@ -339,14 +339,13 @@ VirtioNet::create_packet(int link_offset)
 
 void VirtioNet::transmit(net::Packet_ptr pckt)
 {
-  assert(pckt != nullptr);
-  VDBG_TX("[virtionet] tx: Transmitting %#zu sized packet \n",
-          pckt->size());
   while (pckt != nullptr) {
     if (not Nic::sendq_still_available(sendq.size())) {
-      stat_sendq_limit_dropped_++;
-      return;
+      stat_sendq_limit_dropped_ += pckt->chain_length();
+      break;
     }
+    VDBG_TX("[virtionet] tx: Transmitting %#zu sized packet \n",
+            pckt->size());
     auto tail = pckt->detach_tail();
     sendq.emplace_back(std::move(pckt));
     pckt = std::move(tail);
@@ -363,7 +362,7 @@ void VirtioNet::transmit(net::Packet_ptr pckt)
           sendq.size());
 
   // Transmit all we can directly
-  while (tx_q.num_free() > 1 and sendq.size() > 0)
+  while (tx_q.num_free() > 1 and !sendq.empty())
   {
     VDBG_TX("[virtionet] tx: %u tokens left in TX ring \n",
             tx_q.num_free());