Kernel: Move packet allocation into helper methods

Kernel/Net/NetworkAdapter.cpp

@@ -158,28 +158,14 @@ void NetworkAdapter::did_receive(ReadonlyBytes payload)
         return;
     }
 
-    RefPtr<PacketWithTimestamp> packet;
+    auto packet = acquire_packet_buffer(payload.size());
-
-    if (m_unused_packets.is_empty()) {
-        auto buffer = KBuffer::copy(payload.data(), payload.size());
-        packet = adopt_ref_if_nonnull(new PacketWithTimestamp { move(buffer), kgettimeofday() });
-    } else {
-        packet = m_unused_packets.take_first();
-        if (payload.size() <= packet->buffer.capacity()) {
-            memcpy(packet->buffer.data(), payload.data(), payload.size());
-            packet->buffer.set_size(payload.size());
-            packet->timestamp = kgettimeofday();
-        } else {
-            auto buffer = KBuffer::copy(payload.data(), payload.size());
-            packet = adopt_ref_if_nonnull(new PacketWithTimestamp { move(buffer), kgettimeofday() });
-        }
-    }
-
     if (!packet) {
         dbgln("Discarding packet because we're out of memory");
         return;
     }
 
+    memcpy(packet->buffer.data(), payload.data(), payload.size());
+
     m_packet_queue.append(*packet);
     m_packet_queue_size++;
 
@@ -199,10 +185,39 @@ size_t NetworkAdapter::dequeue_packet(u8* buffer, size_t buffer_size, Time& pack
     size_t packet_size = packet_buffer.size();
     VERIFY(packet_size <= buffer_size);
     memcpy(buffer, packet_buffer.data(), packet_size);
-    m_unused_packets.append(*packet_with_timestamp);
+    release_packet_buffer(*packet_with_timestamp);
     return packet_size;
 }
 
+RefPtr<PacketWithTimestamp> NetworkAdapter::acquire_packet_buffer(size_t size)
+{
+    InterruptDisabler disabler;
+    if (m_unused_packets.is_empty()) {
+        auto buffer = KBuffer::create_with_size(size, Region::Access::Read | Region::Access::Write, "Packet Buffer", AllocationStrategy::AllocateNow);
+        auto packet = adopt_ref_if_nonnull(new PacketWithTimestamp { move(buffer), kgettimeofday() });
+        packet->buffer.set_size(size);
+        return packet;
+    }
+
+    auto packet = m_unused_packets.take_first();
+    if (packet->buffer.capacity() >= size) {
+        packet->timestamp = kgettimeofday();
+        packet->buffer.set_size(size);
+        return packet;
+    }
+
+    auto buffer = KBuffer::create_with_size(size, Region::Access::Read | Region::Access::Write, "Packet Buffer", AllocationStrategy::AllocateNow);
+    packet = adopt_ref_if_nonnull(new PacketWithTimestamp { move(buffer), kgettimeofday() });
+    packet->buffer.set_size(size);
+    return packet;
+}
+
+void NetworkAdapter::release_packet_buffer(PacketWithTimestamp& packet)
+{
+    InterruptDisabler disabler;
+    m_unused_packets.append(packet);
+}
+
 void NetworkAdapter::set_ipv4_address(const IPv4Address& address)
 {
     m_ipv4_address = address;

Kernel/Net/NetworkAdapter.h

@@ -26,6 +26,18 @@ class NetworkAdapter;
 
 using NetworkByteBuffer = AK::Detail::ByteBuffer<1500>;
 
+struct PacketWithTimestamp : public RefCounted<PacketWithTimestamp> {
+    PacketWithTimestamp(KBuffer buffer, Time timestamp)
+        : buffer(move(buffer))
+        , timestamp(timestamp)
+    {
+    }
+
+    KBuffer buffer;
+    Time timestamp;
+    IntrusiveListNode<PacketWithTimestamp, RefPtr<PacketWithTimestamp>> packet_node;
+};
+
 class NetworkAdapter : public RefCounted<NetworkAdapter> {
 public:
     template<typename Callback>
@@ -70,6 +82,9 @@ public:
     u32 packets_out() const { return m_packets_out; }
     u32 bytes_out() const { return m_bytes_out; }
 
+    RefPtr<PacketWithTimestamp> acquire_packet_buffer(size_t);
+    void release_packet_buffer(PacketWithTimestamp&);
+
     Function<void()> on_receive;
 
 protected:
@@ -89,18 +104,6 @@ private:
     IPv4Address m_ipv4_netmask;
     IPv4Address m_ipv4_gateway;
 
-    struct PacketWithTimestamp : public RefCounted<PacketWithTimestamp> {
-        PacketWithTimestamp(KBuffer buffer, Time timestamp)
-            : buffer(move(buffer))
-            , timestamp(timestamp)
-        {
-        }
-
-        KBuffer buffer;
-        Time timestamp;
-        IntrusiveListNode<PacketWithTimestamp, RefPtr<PacketWithTimestamp>> packet_node;
-    };
-
     // FIXME: Make this configurable
     static constexpr size_t max_packet_buffers = 1024;