sockets: Add a function to disable all listening sockets.

When invoking several copies of m5 on the same machine at the same
time, there can be a race for TCP ports for the terminal connections
or remote gdb.  Expose a function to disable those ports, and have the
regression scripts disable them.  There are some SimObjects that have
no other function than to be used with ports (NativeTrace and
EtherTap), so they will panic if the ports are disabled.

src/base/remote_gdb.cc

@@ -195,6 +195,11 @@ GDBListener::name()
 void
 GDBListener::listen()
 {
+    if (ListenSocket::allDisabled()) {
+        warn_once("Sockets disabled, not accepting gdb connections");
+        return;
+    }
+
     while (!listener.listen(port, true)) {
         DPRINTF(GDBMisc, "Can't bind port %d\n", port);
         port++;

src/base/socket.cc

@@ -43,6 +43,23 @@
 
 using namespace std;
 
+bool ListenSocket::listeningDisabled = false;
+bool ListenSocket::anyListening = false;
+
+void
+ListenSocket::disableAll()
+{
+    if (anyListening)
+        panic("Too late to disable all listeners, already have a listener");
+    listeningDisabled = true;
+}
+
+bool
+ListenSocket::allDisabled()
+{
+    return listeningDisabled;
+}
+
 ////////////////////////////////////////////////////////////////////////
 //
 //
@@ -92,6 +109,7 @@ ListenSocket::listen(int port, bool reuse)
 
     listening = true;
 
+    anyListening = true;
     return true;
 }
 

src/base/socket.hh

@@ -33,6 +33,14 @@
 
 class ListenSocket
 {
+  protected:
+    static bool listeningDisabled;
+    static bool anyListening;
+
+  public:
+    static void disableAll();
+    static bool allDisabled();
+
   protected:
     bool listening;
     int fd;

src/cpu/nativetrace.cc

@@ -50,8 +50,12 @@ using namespace TheISA;
 
 namespace Trace {
 
-NativeTrace::NativeTrace(const Params *p) : InstTracer(p)
+NativeTrace::NativeTrace(const Params *p)
+    : InstTracer(p)
 {
+    if (ListenSocket::allDisabled())
+        fatal("All listeners are disabled!");
+
     int port = 8000;
     while(!native_listener.listen(port, true))
     {

src/dev/ethertap.cc

@@ -130,6 +130,9 @@ EtherTap::EtherTap(const Params *p)
     : EtherObject(p), event(NULL), socket(-1), buflen(p->bufsz), dump(p->dump),
       interface(NULL), txEvent(this)
 {
+    if (ListenSocket::allDisabled())
+        fatal("All listeners are disabled! EtherTap can't work!");
+
     buffer = new char[buflen];
     listener = new TapListener(this, p->port);
     listener->listen();

src/dev/terminal.cc

@@ -125,6 +125,11 @@ Terminal::~Terminal()
 void
 Terminal::listen(int port)
 {
+    if (ListenSocket::allDisabled()) {
+        warn_once("Sockets disabled, not accepting terminal connections");
+        return;
+    }
+
     while (!listener.listen(port, true)) {
         DPRINTF(Terminal,
                 ": can't bind address terminal port %d inuse PID %d\n",

src/python/m5/simulate.py

@@ -182,3 +182,5 @@ def switchCpus(cpuList):
 
     for old_cpu, new_cpu in cpuList:
         new_cpu.takeOverFrom(old_cpu)
+
+from internal.core import disableAllListeners

src/python/swig/core.i

@@ -34,6 +34,7 @@
 %{
 #include "python/swig/pyobject.hh"
 
+#include "base/socket.hh"
 #include "sim/core.hh"
 #include "sim/host.hh"
 #include "sim/startup.hh"
@@ -42,6 +43,7 @@ extern const char *compileDate;
 std::vector<std::string> compileFlags();
 extern const char *hgRev;
 extern const char *hgDate;
+inline void disableAllListeners() { ListenSocket::disableAll(); }
 %}
 
 %include "stdint.i"
@@ -53,6 +55,7 @@ void setOutputDir(const std::string &dir);
 void setOutputFile(const std::string &file);
 void SimStartup();
 void doExitCleanup();
+void disableAllListeners();
 
 %immutable compileDate;
 char *compileDate;

tests/run.py

@@ -26,7 +26,12 @@
 #
 # Authors: Steve Reinhardt
 
-import os, sys
+import os
+import sys
+import m5
+
+# Since we're in batch mode, dont allow tcp socket connections
+m5.disableAllListeners()
 
 # single "path" arg encodes everything we need to know about test
 (category, name, isa, opsys, config) = sys.argv[1].split('/')
@@ -57,8 +62,7 @@ execfile(os.path.join(tests_root, 'configs', config + '.py'))
 
 # set default maxtick... script can override
 # -1 means run forever
-from m5 import MaxTick
-maxtick = MaxTick
+maxtick = m5.MaxTick
 
 # tweak configuration for specific test