diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 7a47897ba..ffc0f38b4 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,23 @@
+2012-12-22  Christopher Faylor  <me.cygwin2012@cgf.cx>
+
+	* select.h (select_stuff): Remove variable names from parameter
+	declarations.
+	(select_info): Ditto.
+	(select_record::dump_select_record): Declare new debugging-only
+	function.
+	(select_info): Zero all fields.
+	(select_pipe_info): Ditto.
+	(select_socket_info): Ditto.
+	(select_serial_info): Ditto.
+	(select_mailslot_info): Ditto.
+	* select.cc (select_record::dump_select_record): Define new
+	debugging-only function.
+	(select_stuff::test_and_set): Call dump_select_record when debugging.
+
+	* thread.cc (pthread_mutex::unlock): Revert setting of tid to NULL
+	since, in this context, it is a number, not a pointer.
+	(pthread_spinlock::unlock): Ditto.
+
 2012-12-21  Christopher Faylor  <me.cygwin2012@cgf.cx>
 
 	* sigproc.cc (exit_thread): undef ExitThread or suffer recursion.
diff --git a/winsup/cygwin/select.cc b/winsup/cygwin/select.cc
index c67471cbc..143e8c4e7 100644
--- a/winsup/cygwin/select.cc
+++ b/winsup/cygwin/select.cc
@@ -286,6 +286,22 @@ select_stuff::~select_stuff ()
   destroy ();
 }
 
+#ifdef DEBUGGING
+void
+select_record::dump_select_record ()
+{
+  select_printf ("fd %d, h %p, fh %p, thread_errno %d, windows_handle %p",
+		 fd, h, fh, thread_errno, windows_handle);
+  select_printf ("read_ready %d, write_ready %d, except_ready %d",
+		 read_ready, write_ready, except_ready);
+  select_printf ("read_selected %d, write_selected %d, except_selected %d, except_on_write %d",
+		 read_selected, write_selected, except_selected, except_on_write);
+		     
+  select_printf ("startup %p, peek %p, verify %p cleanup %p, next %p",
+		 startup, peek, verify, cleanup, next);
+}
+#endif /*DEBUGGING*/
+
 /* Add a record to the select chain */
 bool
 select_stuff::test_and_set (int i, fd_set *readfds, fd_set *writefds,
@@ -315,6 +331,9 @@ select_stuff::test_and_set (int i, fd_set *readfds, fd_set *writefds,
   if (s->windows_handle)
     windows_used = true;
 
+#ifdef DEBUGGING
+  s->dump_select_record ();
+#endif
   return true;
 
 err:
diff --git a/winsup/cygwin/select.h b/winsup/cygwin/select.h
index f9df95d93..5e746768c 100644
--- a/winsup/cygwin/select.h
+++ b/winsup/cygwin/select.h
@@ -22,11 +22,10 @@ struct select_record
   bool read_ready, write_ready, except_ready;
   bool read_selected, write_selected, except_selected;
   bool except_on_write;
-  int (*startup) (select_record *me, class select_stuff *stuff);
+  int (*startup) (select_record *, class select_stuff *);
   int (*peek) (select_record *, bool);
-  int (*verify) (select_record *me, fd_set *readfds, fd_set *writefds,
-		 fd_set *exceptfds);
-  void (*cleanup) (select_record *me, class select_stuff *stuff);
+  int (*verify) (select_record *, fd_set *, fd_set *, fd_set *);
+  void (*cleanup) (select_record *, class select_stuff *);
   struct select_record *next;
   void set_select_errno () {__seterrno (); thread_errno = errno;}
   int saw_error () {return thread_errno;}
@@ -37,6 +36,9 @@ struct select_record
     except_selected (false), except_on_write (false),
     startup (NULL), peek (NULL), verify (NULL), cleanup (NULL),
     next (NULL) {}
+#ifdef DEBUGGING
+  void dump_select_record ();
+#endif
 };
 
 struct select_info
@@ -44,11 +46,12 @@ struct select_info
   cygthread *thread;
   bool stop_thread;
   select_record *start;
-  select_info () {}
+  select_info (): thread (NULL), stop_thread (0), start (NULL) {}
 };
 
 struct select_pipe_info: public select_info
 {
+  select_pipe_info (): select_info () {}
 };
 
 struct select_socket_info: public select_info
@@ -56,14 +59,17 @@ struct select_socket_info: public select_info
   int num_w4;
   LONG *ser_num;
   HANDLE *w4;
+  select_socket_info (): select_info (), num_w4 (0), ser_num (0), w4 (NULL) {} 
 };
 
 struct select_serial_info: public select_info
 {
+  select_serial_info (): select_info () {}
 };
 
 struct select_mailslot_info: public select_info
 {
+  select_mailslot_info (): select_info () {}
 };
 
 class select_stuff
@@ -88,10 +94,9 @@ public:
   select_serial_info *device_specific_serial;
   select_mailslot_info *device_specific_mailslot;
 
-  bool test_and_set (int i, fd_set *readfds, fd_set *writefds,
-		     fd_set *exceptfds);
-  int poll (fd_set *readfds, fd_set *writefds, fd_set *exceptfds);
-  wait_states wait (fd_set *readfds, fd_set *writefds, fd_set *exceptfds, DWORD ms);
+  bool test_and_set (int, fd_set *, fd_set *, fd_set *);
+  int poll (fd_set *, fd_set *, fd_set *);
+  wait_states wait (fd_set *, fd_set *, fd_set *, DWORD);
   void cleanup ();
   void destroy ();
 
diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
index 187ea52fd..ba3221cc9 100644
--- a/winsup/cygwin/thread.cc
+++ b/winsup/cygwin/thread.cc
@@ -1778,7 +1778,7 @@ pthread_mutex::unlock ()
     {
       owner = (pthread_t) _unlocked_mutex;
 #ifdef DEBUGGING
-      tid = NULL;
+      tid = 0;		// thread-id
 #endif
       if (InterlockedDecrement ((long *) &lock_counter))
 	::SetEvent (win32_obj_id); // Another thread is waiting
@@ -1905,7 +1905,7 @@ pthread_spinlock::unlock ()
     {
       owner = (pthread_t) _unlocked_mutex;
 #ifdef DEBUGGING
-      tid = NULL;
+      tid = 0;		// thread-id
 #endif
       InterlockedExchange ((long *) &lock_counter, 0);
       ::SetEvent (win32_obj_id);