diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 1ba6827e6..f760764dc 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,16 @@
+2011-04-20  Christopher Faylor  <me.cygwin2011@cgf.cx>
+
+	* cygheap.cc (init_cygheap::close_ctty): Avoid closing console-cttys
+	since they don't use archetypes and this will just result in double
+	frees.
+	* dll_init.cc (dll_list::protect): Define.
+	(dll_list::alloc): Guard list access.
+	(dll_list::detach): Ditto.
+	* dll_init.h (dll_list::protect): Declare new muto.
+	(dll_list::guard): Define/declare function to guard list access.
+	* fhandler_termios.cc (fhandler_termios::sigflush): Avoid SEGV in
+	pathological condition of get_ttyp() == NULL.
+
 2011-04-20  Christopher Faylor  <me.cygwin2011@cgf.cx>
 
 	* select.cc (serial_cleanup): Make sure that device_specific_pipe is
diff --git a/winsup/cygwin/cygheap.cc b/winsup/cygwin/cygheap.cc
index 00e9796f6..8dde3dfe9 100644
--- a/winsup/cygwin/cygheap.cc
+++ b/winsup/cygwin/cygheap.cc
@@ -15,6 +15,7 @@
 #include "cygerrno.h"
 #include "security.h"
 #include "path.h"
+#include "tty.h"
 #include "fhandler.h"
 #include "dtable.h"
 #include "cygheap.h"
@@ -106,7 +107,11 @@ void
 init_cygheap::close_ctty ()
 {
   debug_printf ("closing cygheap->ctty %p", cygheap->ctty);
-  cygheap->ctty->close ();
+  /* FIXME: Support for console-as-ctty is limited due to the fact that
+     the console doesn't use archetypes - even though they could and should */
+  if (cygheap->ctty->get_ttyp ()
+      && cygheap->ctty->get_ttyp ()->ntty != TTY_CONSOLE)
+    cygheap->ctty->close ();
   cygheap->ctty = NULL;
 }
 
diff --git a/winsup/cygwin/dll_init.cc b/winsup/cygwin/dll_init.cc
index 5ee2f0036..f457b2766 100644
--- a/winsup/cygwin/dll_init.cc
+++ b/winsup/cygwin/dll_init.cc
@@ -10,6 +10,7 @@ details. */
 #include "winsup.h"
 #include "cygerrno.h"
 #include "perprocess.h"
+#include "sync.h"
 #include "dll_init.h"
 #include "environ.h"
 #include "security.h"
@@ -28,6 +29,8 @@ extern void __stdcall check_sanity_and_sync (per_process *);
 
 dll_list dlls;
 
+muto dll_list::protect;
+
 static bool dll_global_dtors_recorded;
 
 /* Run destructors for all DLLs on exit. */
@@ -116,6 +119,7 @@ dll_list::alloc (HINSTANCE h, per_process *p, dll_type type)
   WCHAR name[NT_MAX_PATH];
   DWORD namelen = GetModuleFileNameW (h, name, sizeof (name));
 
+  guard (true);
   /* Already loaded? */
   dll *d = dlls[name];
   if (d)
@@ -146,6 +150,7 @@ dll_list::alloc (HINSTANCE h, per_process *p, dll_type type)
       if (type == DLL_LOAD)
 	loaded_dlls++;
     }
+  guard (false);
   assert (p->envptr != NULL);
   return d;
 }
@@ -170,27 +175,32 @@ void
 dll_list::detach (void *retaddr)
 {
   dll *d;
-  if (!myself || !(d = find (retaddr)))
+  if (!myself)
     return;
-  if (d->count <= 0)
-    system_printf ("WARNING: trying to detach an already detached dll ...");
-  if (--d->count == 0)
+  guard (true);
+  if ((d = find (retaddr)))
     {
-      /* Ensure our exception handler is enabled for destructors */
-      exception protect;
-      /* Call finalize function if we are not already exiting */
-      if (!exit_state)
-	__cxa_finalize (d);
-      d->run_dtors ();
-      d->prev->next = d->next;
-      if (d->next)
-	d->next->prev = d->prev;
-      if (d->type == DLL_LOAD)
-	loaded_dlls--;
-      if (end == d)
-	end = d->prev;
-      cfree (d);
+      if (d->count <= 0)
+	system_printf ("WARNING: trying to detach an already detached dll ...");
+      if (--d->count == 0)
+	{
+	  /* Ensure our exception handler is enabled for destructors */
+	  exception protect;
+	  /* Call finalize function if we are not already exiting */
+	  if (!exit_state)
+	    __cxa_finalize (d);
+	  d->run_dtors ();
+	  d->prev->next = d->next;
+	  if (d->next)
+	    d->next->prev = d->prev;
+	  if (d->type == DLL_LOAD)
+	    loaded_dlls--;
+	  if (end == d)
+	    end = d->prev;
+	  cfree (d);
+	}
     }
+  guard (false);
 }
 
 /* Initialization for all linked DLLs, called by dll_crt0_1. */
diff --git a/winsup/cygwin/dll_init.h b/winsup/cygwin/dll_init.h
index b37406e82..d14cc6cb9 100644
--- a/winsup/cygwin/dll_init.h
+++ b/winsup/cygwin/dll_init.h
@@ -72,6 +72,7 @@ class dll_list
   dll *end;
   dll *hold;
   dll_type hold_type;
+  static muto protect;
 public:
   dll start;
   int tot;
@@ -90,13 +91,22 @@ public:
 	break;
     return hold;
   }
+
   dll *istart (dll_type t)
   {
     hold_type = t;
     hold = &start;
     return inext ();
   }
+  void guard(bool lockit)
+  {
+    if (lockit)
+      protect.acquire ();
+    else
+      protect.release ();
+  }
   friend void dll_global_dtors ();
+  dll_list () { protect.init ("dll_list"); }
 };
 
 extern dll_list dlls;
diff --git a/winsup/cygwin/fhandler_termios.cc b/winsup/cygwin/fhandler_termios.cc
index bdfce4642..80131a796 100644
--- a/winsup/cygwin/fhandler_termios.cc
+++ b/winsup/cygwin/fhandler_termios.cc
@@ -371,6 +371,9 @@ fhandler_termios::lseek (_off64_t, int)
 void
 fhandler_termios::sigflush ()
 {
-  if (!(get_ttyp ()->ti.c_lflag & NOFLSH))
+  /* FIXME: Checking get_ttyp() for NULL is not right since it should not
+     be NULL while this is alive.  However, we can conceivably close a
+     ctty while exiting and that will zero this. */
+  if (get_ttyp () && !(get_ttyp ()->ti.c_lflag & NOFLSH))
     tcflush (TCIFLUSH);
 }
diff --git a/winsup/cygwin/sync.cc b/winsup/cygwin/sync.cc
index b62c6bcb7..58b854912 100644
--- a/winsup/cygwin/sync.cc
+++ b/winsup/cygwin/sync.cc
@@ -4,7 +4,7 @@
    which is intended to operate similarly to a mutex but attempts to
    avoid making expensive calls to the kernel.
 
-   Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009 Red Hat, Inc.
+   Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009, 2010 Red Hat, Inc.
 
 This file is part of Cygwin.