Kernel: Add Thread::block_until(Condition).

Replace the class-based snooze alarm mechanism with a per-thread callback.
This makes it easy to block the current thread on an arbitrary condition:

    void SomeDevice::wait_for_irq() {
        m_interrupted = false;
        current->block_until([this] { return m_interrupted; });
    }
    void SomeDevice::handle_irq() {
        m_interrupted = true;
    }

Use this in the SB16 driver, and in NetworkTask :^)

3 files changed, 9 insertions, 42 deletions

diff --git a/Kernel/Net/NetworkAdapter.cpp b/Kernel/Net/NetworkAdapter.cpp
index f1eaffc245..f4ef012c4f 100644
--- a/Kernel/Net/NetworkAdapter.cpp
+++ b/Kernel/Net/NetworkAdapter.cpp
@@ -33,7 +33,6 @@ NetworkAdapter* NetworkAdapter::from_ipv4_address(const IPv4Address& address)
 }
 
 NetworkAdapter::NetworkAdapter()
-    : m_packet_queue_alarm(*this)
 {
     // FIXME: I wanna lock :(
     all_adapters().resource().set(this);
@@ -106,8 +105,3 @@ void NetworkAdapter::set_interface_name(const StringView& basename)
     builder.append('0');
     m_name = builder.to_string();
 }
-
-bool PacketQueueAlarm::is_ringing() const
-{
-    return m_adapter.has_queued_packets();
-}
diff --git a/Kernel/Net/NetworkAdapter.h b/Kernel/Net/NetworkAdapter.h
index 118bb13774..2052b3cc43 100644
--- a/Kernel/Net/NetworkAdapter.h
+++ b/Kernel/Net/NetworkAdapter.h
@@ -4,7 +4,6 @@
 #include <AK/Function.h>
 #include <AK/SinglyLinkedList.h>
 #include <AK/Types.h>
-#include <Kernel/Alarm.h>
 #include <Kernel/Net/ARP.h>
 #include <Kernel/Net/ICMP.h>
 #include <Kernel/Net/IPv4.h>
@@ -12,19 +11,6 @@
 
 class NetworkAdapter;
 
-class PacketQueueAlarm final : public Alarm {
-public:
-    PacketQueueAlarm(NetworkAdapter& adapter)
-        : m_adapter(adapter)
-    {
-    }
-    virtual ~PacketQueueAlarm() override {}
-    virtual bool is_ringing() const override;
-
-private:
-    NetworkAdapter& m_adapter;
-};
-
 class NetworkAdapter {
 public:
     static void for_each(Function<void(NetworkAdapter&)>);
@@ -44,8 +30,6 @@ public:
 
     ByteBuffer dequeue_packet();
 
-    Alarm& packet_queue_alarm() { return m_packet_queue_alarm; }
-
     bool has_queued_packets() const { return !m_packet_queue.is_empty(); }
 
 protected:
@@ -58,7 +42,6 @@ protected:
 private:
     MACAddress m_mac_address;
     IPv4Address m_ipv4_address;
-    PacketQueueAlarm m_packet_queue_alarm;
     SinglyLinkedList<ByteBuffer> m_packet_queue;
     String m_name;
 };
diff --git a/Kernel/Net/NetworkTask.cpp b/Kernel/Net/NetworkTask.cpp
index c680a66135..5c553e7cd2 100644
--- a/Kernel/Net/NetworkTask.cpp
+++ b/Kernel/Net/NetworkTask.cpp
@@ -33,22 +33,6 @@ Lockable<HashMap<IPv4Address, MACAddress>>& arp_table()
     return *the;
 }
 
-class CombinedPacketQueueAlarm : public Alarm {
-public:
-    CombinedPacketQueueAlarm() {}
-
-    virtual bool is_ringing() const override
-    {
-        if (LoopbackAdapter::the().has_queued_packets())
-            return true;
-        if (auto* e1000 = E1000NetworkAdapter::the()) {
-            if (e1000->has_queued_packets())
-                return true;
-        }
-        return false;
-    }
-};
-
 void NetworkTask_main()
 {
     LoopbackAdapter::the();
@@ -71,13 +55,19 @@ void NetworkTask_main()
         return {};
     };
 
-    CombinedPacketQueueAlarm queue_alarm;
-
     kprintf("NetworkTask: Enter main loop.\n");
     for (;;) {
         auto packet = dequeue_packet();
         if (packet.is_null()) {
-            current->snooze_until(queue_alarm);
+            current->block_until([] {
+                if (LoopbackAdapter::the().has_queued_packets())
+                    return true;
+                if (auto* e1000 = E1000NetworkAdapter::the()) {
+                    if (e1000->has_queued_packets())
+                        return true;
+                }
+                return false;
+            });
             continue;
         }
         if (packet.size() < (int)(sizeof(EthernetFrameHeader))) {