* spinlock.h: New file.

(spinlock): New class.
* shared.cc: Include spinlock.h.
(memory_init): Use new spinlock methods rather than roll-your-own.  Time out
after ten seconds if shared_mem_inited is not initialized.
* sync.h: Update copyright.  Remove vanity attribution.
* sigproc.cc (sigproc_terminate): Avoid attempts to kill the signal thread
while we're still initializing or suffer a deadlock.

winsup/cygwin/spinlock.h

@@ -0,0 +1,40 @@
+/* spinlock.h: Header file for cygwin time-sensitive synchronization primitive.
+
+   Copyright 2010 Red Hat, Inc.
+
+This file is part of Cygwin.
+
+This software is a copyrighted work licensed under the terms of the
+Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
+details. */
+
+#ifndef _SPINLOCK_H
+#define _SPINLOCK_H
+
+#include "hires.h"
+
+class spinlock
+{
+  LONG *locker;
+  LONG val;
+public:
+  spinlock (LONG& locktest, LONGLONG timeout):
+    locker (&locktest)
+  {
+    if ((val = locktest) == 1)
+      return;
+    LONGLONG then = gtod.msecs ();
+    for (;;)
+      {
+	if ((val = InterlockedExchange (locker, -1)) != -1
+	    || (gtod.msecs () - then) >= timeout)
+	  break;
+	yield ();
+      }
+  }
+  ~spinlock () {InterlockedExchange (locker, 1);}
+  operator LONG () const {return val;}
+};
+
+#endif /*_SPINLOCK_H*/
+