Kernel/Net: Iron out the locking mechanism across the subsystem

There is a big mix of LockRefPtrs all over the Networking subsystem, as
well as lots of room for improvements with our locking patterns, which
this commit will not pursue, but will give a good start for such work.

To deal with this situation, we change the following things:
- Creating instances of NetworkAdapter should always yield a non-locking
  NonnullRefPtr. Acquiring an instance from the NetworkingManagement
  should give a simple RefPtr,as giving LockRefPtr does not really
  protect from concurrency problems in such case.
- Since NetworkingManagement works with normal RefPtrs we should
  protect all instances of RefPtr<NetworkAdapter> with SpinlockProtected
  to ensure references are gone unexpectedly.
- Protect the so_error class member with a proper spinlock. This happens
  to be important because the clear_so_error() method lacked any proper
  locking measures. It also helps preventing a possible TOCTOU when we
  might do a more fine-grained locking in the Socket code, so this could
  be definitely a start for this.
- Change unnecessary LockRefPtr<PacketWithTimestamp> in the structure
  of OutgoingPacket to a simple RefPtr<PacketWithTimestamp> as the whole
  list should be MutexProtected.

1 files changed, 2 insertions, 2 deletions

diff --git a/Kernel/Net/NetworkTask.cpp b/Kernel/Net/NetworkTask.cpp
index b5de06dda8..a89860452c 100644
--- a/Kernel/Net/NetworkTask.cpp
+++ b/Kernel/Net/NetworkTask.cpp
@@ -31,7 +31,7 @@ static void handle_icmp(EthernetFrameHeader const&, IPv4Packet const&, Time cons
 static void handle_udp(IPv4Packet const&, Time const& packet_timestamp);
 static void handle_tcp(IPv4Packet const&, Time const& packet_timestamp);
 static void send_delayed_tcp_ack(TCPSocket& socket);
-static void send_tcp_rst(IPv4Packet const& ipv4_packet, TCPPacket const& tcp_packet, LockRefPtr<NetworkAdapter> adapter);
+static void send_tcp_rst(IPv4Packet const& ipv4_packet, TCPPacket const& tcp_packet, RefPtr<NetworkAdapter> adapter);
 static void flush_delayed_tcp_acks();
 static void retransmit_tcp_packets();
 
@@ -333,7 +333,7 @@ void flush_delayed_tcp_acks()
     }
 }
 
-void send_tcp_rst(IPv4Packet const& ipv4_packet, TCPPacket const& tcp_packet, LockRefPtr<NetworkAdapter> adapter)
+void send_tcp_rst(IPv4Packet const& ipv4_packet, TCPPacket const& tcp_packet, RefPtr<NetworkAdapter> adapter)
 {
     auto routing_decision = route_to(ipv4_packet.source(), ipv4_packet.destination(), adapter);
     if (routing_decision.is_zero())