Exited threads.

	* thread.c (enum thread_state): New.
	(thread_state main_thread_running): Delete, in favor of...
	(thread_state main_thread_state): ... this.  Update throughout.
	(clear_thread_inferior_resources): New, split from free_thread.
	(free_thread): Call clear_thread_inferior_resources.
	(init_thread_list): Set main thread to stopped state.
	(add_thread_silent): Take care of PTID reuses.
	(delete_thread): If deleting inferior_ptid or a thread with
	refcount > 0, mark it as exited, but still keep it in the list.
	Only notify of thread exits, if we haven't done so yet.
	(iterate_over_threads): Make it safe to delete threads while
	iterating over them.
	(do_captured_list_thread_ids): Don't account for exited threads.
	(thread_alive): Check for the THREAD_EXITED state, and don't set
	ptid to -1 on exited threads.
	(set_running): Update to account for extra possible states.
	(is_thread_state): New.
	(is_stopped, is_exited): New.
	(is_running): Implement in terms of is_thread_state.
	(any_running): Update.
	(print_thread_info): Update.  Account for exited threads.  Don't
	warn about missed frame restoring here, its done in the cleanup.
	(switch_to_thread): Don't read from a thread that has gone.
	(restore_current_thread): In non-stop mode, do a full context
	switch.
	(restore_selected_frame): Add a frame_level argument.  Rewrite.
	(struct current_thread_cleanup): Add selected_frame_level and
	was_stopped members.
	(do_restore_current_thread_cleanup): Check if thread was stopped
	and still is, and if the target has registers, stack and memory
	before restoring the selected frame.  Don't delete the cleanup
	argument here.
	(restore_current_thread_cleanup_dtor): New.
	(make_cleanup_restore_current_thread): Remove all arguments.
	Rewrite.
	(thread_apply_all_command): Update.  Prune threads.
	(thread_apply_command): Update.
	(thread_command): Account for currently selected exited thread.
	(do_captured_thread_select): Check for a running thread.  Prune
	threads.
	(_initialize_thread): Make "info threads", "thread", "thread
	apply", and "thread apply all" appliable without a selected thread.
	* gdbthread.h (struct thread_info): Replace running_ by state_.
	Add refcount.
	(is_exited, is_stopped): Declare.
	(make_cleanup_restore_current_thread): Remove all arguments.
	* infrun.c: Include "event-top.h".
	(fetch_inferior_event): In non-stop mode, restore selected thread
	and frame after handling the event and running breakpoint
	commands.  Display GDB prompt if needed.
	(normal_stop): In non-stop mode, don't print thread switching
	notice.
	* cli/cli-decode.c (set_cmd_no_selected_thread_ok)
	(get_cmd_no_selected_thread_ok): New.
	* cli/cli-decode.h (CMD_NO_SELECTED_THREAD_OK): New.
	(set_cmd_no_selected_thread_ok, get_cmd_no_selected_thread_ok):
	Declare.
	* cli/cli-cmds.c: Set "pwd", "help", "info", "show" as
	no-selected-thread ok.
	* top.c (execute_command): Check for non no-selected-thread-ok
	commands.
	* linux-nat.c (struct saved_ptids, threads_to_delete)
	(record_dead_thread, prune_lwps): Delete.
	(exit_lwp): Unconditionally delete thread.
	(linux_nat_resume): Remove prune_lwps call.
	* infcmd.c (proceed_thread_callback): Check if !is_stopped instead
	of is_running.  Adjust to make_cleanup_restore_current_thread
	interface change.
	* mi/mi-main.c (mi_cmd_execute): Only allow a few commands if the
	selected thread has exited.
	* inf-loop.c (inferior_event_handler): Don't display the prompt
	here.
	* varobj.c (c_value_of_root): Update.
	* defs.h (make_cleanup_dtor): Declare.
	* utils.c (make_cleanup_dtor): New.

	* Makefile.in (infrun.o): Depend on $(event_top_h).

16 files changed, 536 insertions, 226 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index df5cd3d..4c5de49 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,87 @@
 2008-07-11  Pedro Alves  <pedro@codesourcery.com>
 
+	Exited threads.
+
+	* thread.c (enum thread_state): New.
+	(thread_state main_thread_running): Delete, in favor of...
+	(thread_state main_thread_state): ... this.  Update throughout.
+	(clear_thread_inferior_resources): New, split from free_thread.
+	(free_thread): Call clear_thread_inferior_resources.
+	(init_thread_list): Set main thread to stopped state.
+	(add_thread_silent): Take care of PTID reuses.
+	(delete_thread): If deleting inferior_ptid or a thread with
+	refcount > 0, mark it as exited, but still keep it in the list.
+	Only notify of thread exits, if we haven't done so yet.
+	(iterate_over_threads): Make it safe to delete threads while
+	iterating over them.
+	(do_captured_list_thread_ids): Don't account for exited threads.
+	(thread_alive): Check for the THREAD_EXITED state, and don't set
+	ptid to -1 on exited threads.
+	(set_running): Update to account for extra possible states.
+	(is_thread_state): New.
+	(is_stopped, is_exited): New.
+	(is_running): Implement in terms of is_thread_state.
+	(any_running): Update.
+	(print_thread_info): Update.  Account for exited threads.  Don't
+	warn about missed frame restoring here, its done in the cleanup.
+	(switch_to_thread): Don't read from a thread that has gone.
+	(restore_current_thread): In non-stop mode, do a full context
+	switch.
+	(restore_selected_frame): Add a frame_level argument.  Rewrite.
+	(struct current_thread_cleanup): Add selected_frame_level and
+	was_stopped members.
+	(do_restore_current_thread_cleanup): Check if thread was stopped
+	and still is, and if the target has registers, stack and memory
+	before restoring the selected frame.  Don't delete the cleanup
+	argument here.
+	(restore_current_thread_cleanup_dtor): New.
+	(make_cleanup_restore_current_thread): Remove all arguments.
+	Rewrite.
+	(thread_apply_all_command): Update.  Prune threads.
+	(thread_apply_command): Update.
+	(thread_command): Account for currently selected exited thread.
+	(do_captured_thread_select): Check for a running thread.  Prune
+	threads.
+	(_initialize_thread): Make "info threads", "thread", "thread
+	apply", and "thread apply all" appliable without a selected thread.
+	* gdbthread.h (struct thread_info): Replace running_ by state_.
+	Add refcount.
+	(is_exited, is_stopped): Declare.
+	(make_cleanup_restore_current_thread): Remove all arguments.
+	* infrun.c: Include "event-top.h".
+	(fetch_inferior_event): In non-stop mode, restore selected thread
+	and frame after handling the event and running breakpoint
+	commands.  Display GDB prompt if needed.
+	(normal_stop): In non-stop mode, don't print thread switching
+	notice.
+	* cli/cli-decode.c (set_cmd_no_selected_thread_ok)
+	(get_cmd_no_selected_thread_ok): New.
+	* cli/cli-decode.h (CMD_NO_SELECTED_THREAD_OK): New.
+	(set_cmd_no_selected_thread_ok, get_cmd_no_selected_thread_ok):
+	Declare.
+	* cli/cli-cmds.c: Set "pwd", "help", "info", "show" as
+	no-selected-thread ok.
+	* top.c (execute_command): Check for non no-selected-thread-ok
+	commands.
+	* linux-nat.c (struct saved_ptids, threads_to_delete)
+	(record_dead_thread, prune_lwps): Delete.
+	(exit_lwp): Unconditionally delete thread.
+	(linux_nat_resume): Remove prune_lwps call.
+	* infcmd.c (proceed_thread_callback): Check if !is_stopped instead
+	of is_running.  Adjust to make_cleanup_restore_current_thread
+	interface change.
+	* mi/mi-main.c (mi_cmd_execute): Only allow a few commands if the
+	selected thread has exited.
+	* inf-loop.c (inferior_event_handler): Don't display the prompt
+	here.
+	* varobj.c (c_value_of_root): Update.
+	* defs.h (make_cleanup_dtor): Declare.
+	* utils.c (make_cleanup_dtor): New.
+
+	* Makefile.in (infrun.o): Depend on $(event_top_h).
+
+2008-07-11  Pedro Alves  <pedro@codesourcery.com>
+
 	Add "continue -a" and "interrupt -a" options for non-stop mode.
 
 	* infcmd.c (proceed_thread_callback, do_context_switch_to): New.
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index efa18ea..7ae8420 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -2335,7 +2335,7 @@ infrun.o: infrun.c $(defs_h) $(gdb_string_h) $(symtab_h) $(frame_h) \
 	$(gdbcore_h) $(gdbcmd_h) $(cli_script_h) $(target_h) $(gdbthread_h) \
 	$(annotate_h) $(symfile_h) $(top_h) $(inf_loop_h) $(regcache_h) \
 	$(value_h) $(observer_h) $(language_h) $(solib_h) $(gdb_assert_h) \
-	$(mi_common_h) $(main_h)
+	$(mi_common_h) $(main_h) $(event_top_h)
 inf-ttrace.o: inf-ttrace.c $(defs_h) $(command_h) $(gdbcore_h) \
 	$(gdbthread_h) $(inferior_h) $(target_h) \
 	$(gdb_assert_h) $(gdb_string_h) $(inf_child_h) $(inf_ttrace_h)
diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index b0f5fa0..efd3137 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -1245,6 +1245,8 @@ The commands below can be used to select other frames by number or address."),
   c = add_com ("pwd", class_files, pwd_command, _("\
 Print working directory.  This is used for your program as well."));
   set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
+
   c = add_cmd ("cd", class_files, cd_command, _("\
 Set working directory to DIR for debugger and program being debugged.\n\
 The change does not take effect for the program being debugged\n\
@@ -1285,6 +1287,7 @@ when GDB is started."), gdbinit);
 	       _("Print list of commands."));
   set_cmd_completer (c, command_completer);
   set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
   add_com_alias ("q", "quit", class_support, 1);
   add_com_alias ("h", "help", class_support, 1);
 
@@ -1314,6 +1317,7 @@ Without an argument, history expansion is enabled."),
 Generic command for showing things about the program being debugged."),
 		      &infolist, "info ", 0, &cmdlist);
   set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
   add_com_alias ("i", "info", class_info, 1);
 
   add_com ("complete", class_obscure, complete_command,
@@ -1323,6 +1327,7 @@ Generic command for showing things about the program being debugged."),
 Generic command for showing things about the debugger."),
 		      &showlist, "show ", 0, &cmdlist);
   set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
   /* Another way to get at the same thing.  */
   add_info ("set", show_command, _("Show all GDB settings."));
 
diff --git a/gdb/cli/cli-decode.c b/gdb/cli/cli-decode.c
index 05a0b27..07bb587 100644
--- a/gdb/cli/cli-decode.c
+++ b/gdb/cli/cli-decode.c
@@ -117,6 +117,18 @@ get_cmd_async_ok (struct cmd_list_element *cmd)
   return cmd->flags & CMD_ASYNC_OK;
 }
 
+void
+set_cmd_no_selected_thread_ok (struct cmd_list_element *cmd)
+{
+  cmd->flags |= CMD_NO_SELECTED_THREAD_OK;
+}
+
+int
+get_cmd_no_selected_thread_ok (struct cmd_list_element *cmd)
+{
+  return cmd->flags & CMD_NO_SELECTED_THREAD_OK;
+}
+
 enum cmd_types
 cmd_type (struct cmd_list_element *cmd)
 {
diff --git a/gdb/cli/cli-decode.h b/gdb/cli/cli-decode.h
index f133b3d..c790398 100644
--- a/gdb/cli/cli-decode.h
+++ b/gdb/cli/cli-decode.h
@@ -51,6 +51,10 @@ cmd_types;
 /* This flag is set if the command is allowed during async execution.  */
 #define CMD_ASYNC_OK              0x8
 
+/* This flag is set if the command is allowed to run when the target
+   has execution, but there's no selected thread.  */
+#define CMD_NO_SELECTED_THREAD_OK 0x10
+
 struct cmd_list_element
   {
     /* Points to next command in this list.  */
@@ -253,6 +257,13 @@ extern void set_cmd_async_ok (struct cmd_list_element *);
 /* Return true if command is async-ok.  */
 extern int get_cmd_async_ok (struct cmd_list_element *);
 
+/* Mark command as ok to call when there is no selected thread.  There
+   is no way to disable this once set.  */
+extern void set_cmd_no_selected_thread_ok (struct cmd_list_element *);
+
+/* Return true if command is no-selected-thread-ok.  */
+extern int get_cmd_no_selected_thread_ok (struct cmd_list_element *);
+
 extern struct cmd_list_element *lookup_cmd (char **,
 					    struct cmd_list_element *, char *,
 					    int, int);
diff --git a/gdb/defs.h b/gdb/defs.h
index 2195ee8..1f1a4bd 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -333,6 +333,9 @@ typedef void (make_cleanup_ftype) (void *);
 
 extern struct cleanup *make_cleanup (make_cleanup_ftype *, void *);
 
+extern struct cleanup *make_cleanup_dtor (make_cleanup_ftype *, void *,
+					  void (*dtor) (void *));
+
 extern struct cleanup *make_cleanup_freeargv (char **);
 
 struct ui_file;
diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index 76b8f6c..3f1d217 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -45,15 +45,21 @@ struct thread_info
      use is_executing instead.  */
   int executing_;
 
-  /* Frontend view of the running state.  Note that this is different
-     from EXECUTING.  When the thread is stopped internally while
-     handling an internal event, like a software single-step
-     breakpoint, executing will be false, but running will still be
-     true.  As a possible future extension, this could turn into
-     enum { stopped, stepping, finishing, until(ling), ... }  */
+  /* Frontend view of the thread state.  Note that the RUNNING/STOPPED
+     states are different from EXECUTING.  When the thread is stopped
+     internally while handling an internal event, like a software
+     single-step breakpoint, EXECUTING will be false, but running will
+     still be true.  As a possible future extension, this could turn
+     into enum { stopped, exited, stepping, finishing, until(ling),
+     running ... }  */
   /* This field is internal to thread.c.  Never access it directly,
      use is_running instead.  */
-  int running_;
+  int state_;
+
+  /* If this is > 0, then it means there's code out there that relies
+     on this thread being listed.  Don't delete it from the lists even
+     if we detect it exiting.  */
+  int refcount;
 
   /* State from wait_for_inferior */
   CORE_ADDR prev_pc;
@@ -207,6 +213,13 @@ extern int is_running (ptid_t ptid);
 /* Reports if any thread is known to be running right now.  */
 extern int any_running (void);
 
+/* Is this thread listed, but known to have exited?  We keep it listed
+   (but not visible) until it's safe to delete.  */
+extern int is_exited (ptid_t ptid);
+
+/* Is this thread stopped?  */
+extern int is_stopped (ptid_t ptid);
+
 /* Marks thread PTID as executing, or as stopped.
    If PIDGET (PTID) is -1, marks all threads.  */
 extern void set_executing (ptid_t ptid, int executing);
@@ -223,8 +236,7 @@ extern int print_thread_events;
 
 extern void print_thread_info (struct ui_out *uiout, int thread);
 
-extern struct cleanup *make_cleanup_restore_current_thread (ptid_t,
-                                                            struct frame_id);
+extern struct cleanup *make_cleanup_restore_current_thread (void);
 
 
 #endif /* GDBTHREAD_H */
diff --git a/gdb/inf-loop.c b/gdb/inf-loop.c
index 94ced19..0572d8c 100644
--- a/gdb/inf-loop.c
+++ b/gdb/inf-loop.c
@@ -116,20 +116,8 @@ inferior_event_handler (enum inferior_event_type event_type,
 	  bpstat_do_actions (&stop_bpstat);
 	}
 
-      /* If no breakpoint command resumed the inferior, prepare for
-	 interaction with the user.  */
-      if (!is_running (inferior_ptid))
-	{
-	  if (was_sync)
-	    {
-	      display_gdb_prompt (0);
-	    }
-	  else
-	    {
-	      if (exec_done_display_p)
-		printf_unfiltered (_("completed.\n"));
-	    }
-	}
+      if (!was_sync && !is_running (inferior_ptid) && exec_done_display_p)
+	printf_unfiltered (_("completed.\n"));
       break;
 
     case INF_EXEC_CONTINUE:
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index c62739a..f5fd018 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -611,7 +611,7 @@ start_command (char *args, int from_tty)
 static int
 proceed_thread_callback (struct thread_info *thread, void *arg)
 {
-  if (is_running (thread->ptid))
+  if (!is_stopped (thread->ptid))
     return 0;
 
   context_switch_to (thread->ptid);
@@ -696,19 +696,13 @@ Can't resume all threads and specify proceed count simultaneously."));
 
   if (non_stop && all_threads)
     {
-      struct cleanup *old_chain;
-      struct frame_id saved_frame_id;
-
       /* Don't error out if the current thread is running, because
 	 there may be other stopped threads.  */
+      struct cleanup *old_chain;
 
       /* Backup current thread and selected frame.  */
-      if (!is_running (inferior_ptid))
-	saved_frame_id = get_frame_id (get_selected_frame (NULL));
-      else
-	saved_frame_id = null_frame_id;
+      old_chain = make_cleanup_restore_current_thread ();
 
-      old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
       iterate_over_threads (proceed_thread_callback, NULL);
 
       /* Restore selected ptid.  */
diff --git a/gdb/infrun.c b/gdb/infrun.c
index f74b945..44e6790 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -48,6 +48,7 @@
 
 #include "gdb_assert.h"
 #include "mi/mi-common.h"
+#include "event-top.h"
 
 /* Prototypes for local functions */
 
@@ -1530,11 +1531,20 @@ fetch_inferior_event (void *client_data)
 {
   struct execution_control_state ecss;
   struct execution_control_state *ecs = &ecss;
+  struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);
+  int was_sync = sync_execution;
 
   memset (ecs, 0, sizeof (*ecs));
 
   overlay_cache_invalid = 1;
 
+  if (non_stop)
+    /* In non-stop mode, the user/frontend should not notice a thread
+       switch due to internal events.  Make sure we reverse to the
+       user selected thread and frame after handling the event and
+       running any breakpoint commands.  */
+    make_cleanup_restore_current_thread ();
+
   /* We have to invalidate the registers BEFORE calling target_wait
      because they can be loaded from the target while in target_wait.
      This makes remote debugging a bit more efficient for those
@@ -1571,6 +1581,14 @@ fetch_inferior_event (void *client_data)
       else
 	inferior_event_handler (INF_EXEC_COMPLETE, NULL);
     }
+
+  /* Revert thread and frame.  */
+  do_cleanups (old_chain);
+
+  /* If the inferior was in sync execution mode, and now isn't,
+     restore the prompt.  */
+  if (was_sync && !sync_execution)
+    display_gdb_prompt (0);
 }
 
 /* Prepare an execution control state for looping through a
@@ -3709,6 +3727,11 @@ normal_stop (void)
 
   get_last_target_status (&last_ptid, &last);
 
+  /* In non-stop mode, we don't want GDB to switch threads behind the
+     user's back, to avoid races where the user is typing a command to
+     apply to thread x, but GDB switches to thread y before the user
+     finishes entering the command.  */
+
   /* As with the notification of thread events, we want to delay
      notifying the user that we've switched thread context until
      the inferior actually stops.
@@ -3716,7 +3739,8 @@ normal_stop (void)
      There's no point in saying anything if the inferior has exited.
      Note that SIGNALLED here means "exited with a signal", not
      "received a signal".  */
-  if (!ptid_equal (previous_inferior_ptid, inferior_ptid)
+  if (!non_stop
+      && !ptid_equal (previous_inferior_ptid, inferior_ptid)
       && target_has_execution
       && last.kind != TARGET_WAITKIND_SIGNALLED
       && last.kind != TARGET_WAITKIND_EXITED)
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index ed13014..967beb4 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -1077,48 +1077,12 @@ linux_nat_switch_fork (ptid_t new_ptid)
 {
   struct lwp_info *lp;
 
-  init_thread_list ();
   init_lwp_list ();
   lp = add_lwp (new_ptid);
-  add_thread_silent (new_ptid);
   lp->stopped = 1;
-}
-
-/* Record a PTID for later deletion.  */
-
-struct saved_ptids
-{
-  ptid_t ptid;
-  struct saved_ptids *next;
-};
-static struct saved_ptids *threads_to_delete;
-
-static void
-record_dead_thread (ptid_t ptid)
-{
-  struct saved_ptids *p = xmalloc (sizeof (struct saved_ptids));
-  p->ptid = ptid;
-  p->next = threads_to_delete;
-  threads_to_delete = p;
-}
 
-/* Delete any dead threads which are not the current thread.  */
-
-static void
-prune_lwps (void)
-{
-  struct saved_ptids **p = &threads_to_delete;
-
-  while (*p)
-    if (! ptid_equal ((*p)->ptid, inferior_ptid))
-      {
-	struct saved_ptids *tmp = *p;
-	delete_thread (tmp->ptid);
-	*p = tmp->next;
-	xfree (tmp);
-      }
-    else
-      p = &(*p)->next;
+  init_thread_list ();
+  add_thread_silent (new_ptid);
 }
 
 /* Handle the exit of a single thread LP.  */
@@ -1133,11 +1097,7 @@ exit_lwp (struct lwp_info *lp)
       if (print_thread_events)
 	printf_unfiltered (_("[%s exited]\n"), target_pid_to_str (lp->ptid));
 
-      /* Core GDB cannot deal with us deleting the current thread.  */
-      if (!ptid_equal (lp->ptid, inferior_ptid))
-	delete_thread (lp->ptid);
-      else
-	record_dead_thread (lp->ptid);
+      delete_thread (lp->ptid);
     }
 
   delete_lwp (lp->ptid);
@@ -1675,8 +1635,6 @@ linux_nat_resume (ptid_t ptid, int step, enum target_signal signo)
 			signo ? strsignal (signo) : "0",
 			target_pid_to_str (inferior_ptid));
 
-  prune_lwps ();
-
   if (target_can_async_p ())
     /* Block events while we're here.  */
     linux_nat_async_events (sigchld_sync);
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 06e9d63..a82d2f0 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1059,6 +1059,24 @@ mi_cmd_execute (struct mi_parse *parse)
 
   if (parse->cmd->argv_func != NULL)
     {
+      if (target_can_async_p ()
+	  && target_has_execution
+	  && (is_exited (inferior_ptid))
+	  && (strcmp (parse->command, "thread-info") != 0
+	      && strcmp (parse->command, "thread-list-ids") != 0
+	      && strcmp (parse->command, "thread-select") != 0))
+	{
+	  struct ui_file *stb;
+	  stb = mem_fileopen ();
+
+	  fputs_unfiltered ("Cannot execute command ", stb);
+	  fputstr_unfiltered (parse->command, '"', stb);
+	  fputs_unfiltered (" without a selected thread", stb);
+
+	  make_cleanup_ui_file_delete (stb);
+	  error_stream (stb);
+	}
+
       if ((!non_stop && any_running ())
 	  || (non_stop && is_running (inferior_ptid)))
 	{
diff --git a/gdb/thread.c b/gdb/thread.c
index 1ae9adf..c3a63fc 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -41,7 +41,6 @@
 #include "ui-out.h"
 #include "observer.h"
 #include "annotate.h"
-
 #include "cli/cli-decode.h"
 
 /* Definition of struct thread_info exported to gdbthread.h */
@@ -65,7 +64,16 @@ static void thread_apply_command (char *, int);
 static void restore_current_thread (ptid_t);
 static void prune_threads (void);
 
-static int main_thread_running = 0;
+/* Frontend view of the thread state.  Possible extensions: stepping,
+   finishing, until(ling),...  */
+enum thread_state
+{
+  THREAD_STOPPED,
+  THREAD_RUNNING,
+  THREAD_EXITED,
+};
+
+static enum thread_state main_thread_state = THREAD_STOPPED;
 static int main_thread_executing = 0;
 
 void
@@ -86,16 +94,25 @@ delete_step_resume_breakpoint (void *arg)
 }
 
 static void
-free_thread (struct thread_info *tp)
+clear_thread_inferior_resources (struct thread_info *tp)
 {
   /* NOTE: this will take care of any left-over step_resume breakpoints,
      but not any user-specified thread-specific breakpoints.  We can not
      delete the breakpoint straight-off, because the inferior might not
      be stopped at the moment.  */
   if (tp->step_resume_breakpoint)
-    tp->step_resume_breakpoint->disposition = disp_del_at_next_stop;
+    {
+      tp->step_resume_breakpoint->disposition = disp_del_at_next_stop;
+      tp->step_resume_breakpoint = NULL;
+    }
 
   bpstat_clear (&tp->stop_bpstat);
+}
+
+static void
+free_thread (struct thread_info *tp)
+{
+  clear_thread_inferior_resources (tp);
 
   /* FIXME: do I ever need to call the back-end to give it a
      chance at this private data before deleting the thread?  */
@@ -111,7 +128,7 @@ init_thread_list (void)
   struct thread_info *tp, *tpnext;
 
   highest_thread_num = 0;
-  main_thread_running = 0;
+  main_thread_state = THREAD_STOPPED;
   main_thread_executing = 0;
 
   if (!thread_list)
@@ -131,6 +148,49 @@ add_thread_silent (ptid_t ptid)
 {
   struct thread_info *tp;
 
+  tp = find_thread_pid (ptid);
+  if (tp)
+    /* Found an old thread with the same id.  It has to be dead,
+       otherwise we wouldn't be adding a new thread with the same id.
+       The OS is reusing this id --- delete it, and recreate a new
+       one.  */
+    {
+      /* In addition to deleting the thread, if this is the current
+	 thread, then we need to also get rid of the current infrun
+	 context, and take care that delete_thread doesn't really
+	 delete the thread if it is inferior_ptid.  Create a new
+	 template thread in the list with an invalid ptid, context
+	 switch to it, delete the original thread, reset the new
+	 thread's ptid, and switch to it.  */
+
+      if (ptid_equal (inferior_ptid, ptid))
+	{
+	  tp = xmalloc (sizeof (*tp));
+	  memset (tp, 0, sizeof (*tp));
+	  tp->ptid = minus_one_ptid;
+	  tp->num = ++highest_thread_num;
+	  tp->next = thread_list;
+	  thread_list = tp;
+	  context_switch_to (minus_one_ptid);
+
+	  /* Now we can delete it.  */
+	  delete_thread (ptid);
+
+	  /* Since the context is already set to this new thread,
+	     reset its ptid, and reswitch inferior_ptid to it.  */
+	  tp->ptid = ptid;
+	  switch_to_thread (ptid);
+
+	  observer_notify_new_thread (tp);
+
+	  /* All done.  */
+	  return tp;
+	}
+      else
+	/* Just go ahead and delete it.  */
+	delete_thread (ptid);
+    }
+
   tp = (struct thread_info *) xmalloc (sizeof (*tp));
   memset (tp, 0, sizeof (*tp));
   tp->ptid = ptid;
@@ -179,17 +239,44 @@ delete_thread_1 (ptid_t ptid, int silent)
   if (!tp)
     return;
 
+  /* If this is the current thread, or there's code out there that
+     relies on it existing (refcount > 0) we can't delete yet.  Mark
+     it as exited, and notify it.  */
+  if (tp->refcount > 0
+      || ptid_equal (tp->ptid, inferior_ptid))
+    {
+      if (tp->state_ != THREAD_EXITED)
+	{
+	  if (!silent)
+	    observer_notify_thread_exit (tp);
+
+	  /* Tag it as exited.  */
+	  tp->state_ = THREAD_EXITED;
+
+	  /* Clear breakpoints, etc. associated with this thread.  */
+	  clear_thread_inferior_resources (tp);
+	}
+
+       /* Will be really deleted some other time.  */
+       return;
+     }
+
   if (tpprev)
     tpprev->next = tp->next;
   else
     thread_list = tp->next;
 
-  if (!silent)
+  /* Notify thread exit, but only if we haven't already.  */
+  if (!silent && tp->state_ != THREAD_EXITED)
     observer_notify_thread_exit (tp);
 
   free_thread (tp);
 }
 
+/* Delete thread PTID and notify of thread exit.  If this is
+   inferior_ptid, don't actually delete it, but tag it as exited and
+   do the notification.  If PTID is the user selected thread, clear
+   it.  */
 void
 delete_thread (ptid_t ptid)
 {
@@ -245,11 +332,14 @@ struct thread_info *
 iterate_over_threads (int (*callback) (struct thread_info *, void *),
 		      void *data)
 {
-  struct thread_info *tp;
+  struct thread_info *tp, *next;
 
-  for (tp = thread_list; tp; tp = tp->next)
-    if ((*callback) (tp, data))
-      return tp;
+  for (tp = thread_list; tp; tp = next)
+    {
+      next = tp->next;
+      if ((*callback) (tp, data))
+	return tp;
+    }
 
   return NULL;
 }
@@ -328,6 +418,8 @@ do_captured_list_thread_ids (struct ui_out *uiout, void *arg)
 
   for (tp = thread_list; tp; tp = tp->next)
     {
+      if (tp->state_ == THREAD_EXITED)
+	continue;
       num++;
       ui_out_field_int (uiout, "thread-id", tp->num);
     }
@@ -478,13 +570,10 @@ save_infrun_state (ptid_t ptid,
 static int
 thread_alive (struct thread_info *tp)
 {
-  if (PIDGET (tp->ptid) == -1)
+  if (tp->state_ == THREAD_EXITED)
     return 0;
   if (!target_thread_alive (tp->ptid))
-    {
-      tp->ptid = pid_to_ptid (-1);	/* Mark it as dead */
-      return 0;
-    }
+    return 0;
   return 1;
 }
 
@@ -516,9 +605,11 @@ set_running (ptid_t ptid, int running)
 	 the main thread is always present in the thread list.  If it's
 	 not, the first call to context_switch will mess up GDB internal
 	 state.  */
-      if (running && !main_thread_running && !suppress_resume_observer)
+      if (running
+ 	  && main_thread_state != THREAD_RUNNING
+ 	  && !suppress_resume_observer)
 	observer_notify_target_resumed (ptid);
-      main_thread_running = running;
+      main_thread_state = running ? THREAD_RUNNING : THREAD_STOPPED;
       return;
     }
 
@@ -530,25 +621,31 @@ set_running (ptid_t ptid, int running)
       int any_started = 0;
       for (tp = thread_list; tp; tp = tp->next)
 	{
-	  if (running && !tp->running_)
-	    any_started = 1;
-	  tp->running_ = running;
+ 	  if (tp->state_ == THREAD_EXITED)
+  	    continue;
+  	  if (running && tp->state_ == THREAD_STOPPED)
+  	    any_started = 1;
+ 	  tp->state_ = running ? THREAD_RUNNING : THREAD_STOPPED;
 	}
       if (any_started && !suppress_resume_observer)
 	observer_notify_target_resumed (ptid);      
     }
   else
     {
+      int started = 0;
       tp = find_thread_pid (ptid);
       gdb_assert (tp);
-      if (running && !tp->running_ && !suppress_resume_observer)
-	observer_notify_target_resumed (ptid);
-      tp->running_ = running;
-    }  
+      gdb_assert (tp->state_ != THREAD_EXITED);
+      if (running && tp->state_ == THREAD_STOPPED)
+ 	started = 1;
+      tp->state_ = running ? THREAD_RUNNING : THREAD_STOPPED;
+      if (started && !suppress_resume_observer)
+  	observer_notify_target_resumed (ptid);
+    }
 }
 
-int
-is_running (ptid_t ptid)
+static int
+is_thread_state (ptid_t ptid, enum thread_state state)
 {
   struct thread_info *tp;
 
@@ -556,11 +653,41 @@ is_running (ptid_t ptid)
     return 0;
 
   if (!thread_list)
-    return main_thread_running;
+    return main_thread_state == state;
 
   tp = find_thread_pid (ptid);
   gdb_assert (tp);
-  return tp->running_;  
+  return tp->state_ == state;
+}
+
+int
+is_stopped (ptid_t ptid)
+{
+  /* Without execution, this property is always true.  */
+  if (!target_has_execution)
+    return 1;
+
+  return is_thread_state (ptid, THREAD_STOPPED);
+}
+
+int
+is_exited (ptid_t ptid)
+{
+  /* Without execution, this property is always false.  */
+  if (!target_has_execution)
+    return 0;
+
+  return is_thread_state (ptid, THREAD_EXITED);
+}
+
+int
+is_running (ptid_t ptid)
+{
+   /* Without execution, this property is always false.  */
+  if (!target_has_execution)
+    return 0;
+
+  return is_thread_state (ptid, THREAD_RUNNING);
 }
 
 int
@@ -572,10 +699,10 @@ any_running (void)
     return 0;
 
   if (!thread_list)
-    return main_thread_running;
+    return main_thread_state == THREAD_RUNNING;
 
   for (tp = thread_list; tp; tp = tp->next)
-    if (tp->running_)
+    if (tp->state_ == THREAD_RUNNING)
       return 1;
 
   return 0;
@@ -627,7 +754,7 @@ set_executing (ptid_t ptid, int executing)
 /* Prints the list of threads and their details on UIOUT.
    This is a version of 'info_thread_command' suitable for
    use from MI.  
-   If REQESTED_THREAD is not -1, it's the GDB id of the thread
+   If REQUESTED_THREAD is not -1, it's the GDB id of the thread
    that should be printed.  Otherwise, all threads are
    printed.  */
 void
@@ -635,24 +762,18 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
 {
   struct thread_info *tp;
   ptid_t current_ptid;
-  struct frame_info *cur_frame;
   struct cleanup *old_chain;
-  struct frame_id saved_frame_id;
   char *extra_info;
   int current_thread = -1;
 
-  /* Backup current thread and selected frame.  */
-  if (!is_running (inferior_ptid))
-    saved_frame_id = get_frame_id (get_selected_frame (NULL));
-  else
-    saved_frame_id = null_frame_id;
-
-  old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
-  make_cleanup_ui_out_list_begin_end (uiout, "threads");
-
   prune_threads ();
   target_find_new_threads ();
   current_ptid = inferior_ptid;
+
+  /* We'll be switching threads temporarily.  */
+  old_chain = make_cleanup_restore_current_thread ();
+
+  make_cleanup_ui_out_list_begin_end (uiout, "threads");
   for (tp = thread_list; tp; tp = tp->next)
     {
       struct cleanup *chain2;
@@ -660,13 +781,16 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
       if (requested_thread != -1 && tp->num != requested_thread)
 	continue;
 
+      if (ptid_equal (tp->ptid, current_ptid))
+	current_thread = tp->num;
+
+      if (tp->state_ == THREAD_EXITED)
+	continue;
+
       chain2 = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 
       if (ptid_equal (tp->ptid, current_ptid))
-	{
-	  current_thread = tp->num;
-	  ui_out_text (uiout, "* ");
-	}
+	ui_out_text (uiout, "* ");
       else
 	ui_out_text (uiout, "  ");
 
@@ -674,15 +798,19 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
       ui_out_text (uiout, " ");
       ui_out_field_string (uiout, "target-id", target_tid_to_str (tp->ptid));
 
-      extra_info = target_extra_thread_info (tp);
-      if (extra_info)
+      if (tp->state_ != THREAD_EXITED)
 	{
-	  ui_out_text (uiout, " (");
-	  ui_out_field_string (uiout, "details", extra_info);
-	  ui_out_text (uiout, ")");
+	  extra_info = target_extra_thread_info (tp);
+	  if (extra_info)
+	    {
+	      ui_out_text (uiout, " (");
+	      ui_out_field_string (uiout, "details", extra_info);
+	      ui_out_text (uiout, ")");
+	    }
+	  ui_out_text (uiout, "  ");
 	}
-      ui_out_text (uiout, "  ");
-      if (tp->running_)
+
+      if (tp->state_ == THREAD_RUNNING)
 	ui_out_text (uiout, "(running)\n");
       else
 	{
@@ -704,24 +832,15 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
 
   if (requested_thread == -1)
     {
-      gdb_assert (current_thread != -1 || !thread_list);
+      gdb_assert (current_thread != -1
+		  || !thread_list);
       if (current_thread != -1 && ui_out_is_mi_like_p (uiout))
 	ui_out_field_int (uiout, "current-thread-id", current_thread);
-    }
-
-  if (is_running (inferior_ptid))
-    return;
 
-  /*  If case we were not able to find the original frame, print the
-      new selected frame.  */
-  if (frame_find_by_id (saved_frame_id) == NULL)
-    {
-      warning (_("Couldn't restore frame in current thread, at frame 0"));
-      /* For MI, we should probably have a notification about
-	 current frame change.  But this error is not very likely, so
-	 don't bother for now.  */
-      if (!ui_out_is_mi_like_p (uiout))
-	print_stack_frame (get_selected_frame (NULL), 0, LOCATION);
+      if (current_thread != -1 && is_exited (current_ptid))
+	ui_out_message (uiout, 0, "\n\
+The current thread <Thread ID %d> has terminated.  See `help thread'.\n",
+			current_thread);
     }
 }
 
@@ -751,7 +870,10 @@ switch_to_thread (ptid_t ptid)
   reinit_frame_cache ();
   registers_changed ();
 
-  if (!is_executing (ptid))
+  /* We don't check for is_stopped, because we're called at times
+     while in the TARGET_RUNNING state, e.g., while handling an
+     internal event.  */
+  if (!is_exited (ptid) && !is_executing (ptid))
     stop_pc = read_pc ();
   else
     stop_pc = ~(CORE_ADDR) 0;
@@ -762,21 +884,63 @@ restore_current_thread (ptid_t ptid)
 {
   if (!ptid_equal (ptid, inferior_ptid))
     {
-      switch_to_thread (ptid);
+      if (non_stop)
+	context_switch_to (ptid);
+      else
+	switch_to_thread (ptid);
     }
 }
 
 static void
-restore_selected_frame (struct frame_id a_frame_id)
+restore_selected_frame (struct frame_id a_frame_id, int frame_level)
 {
-  struct frame_info *selected_frame_info = NULL;
+  struct frame_info *frame = NULL;
+  int count;
+
+  gdb_assert (frame_level >= 0);
+
+  /* Restore by level first, check if the frame id is the same as
+     expected.  If that fails, try restoring by frame id.  If that
+     fails, nothing to do, just warn the user.  */
+
+  count = frame_level;
+  frame = find_relative_frame (get_current_frame (), &count);
+  if (count == 0
+      && frame != NULL
+      /* Either the frame ids match, of they're both invalid.  The
+	 latter case is not failsafe, but since it's highly unlikely
+	 the search by level finds the wrong frame, it's 99.9(9)% of
+	 the time (for all practical purposes) safe.  */
+      && (frame_id_eq (get_frame_id (frame), a_frame_id)
+	  /* Note: could be better to check every frame_id
+	     member for equality here.  */
+	  || (!frame_id_p (get_frame_id (frame))
+	      && !frame_id_p (a_frame_id))))
+    {
+      /* Cool, all is fine.  */
+      select_frame (frame);
+      return;
+    }
 
-  if (frame_id_eq (a_frame_id, null_frame_id))
-    return;        
+  frame = frame_find_by_id (a_frame_id);
+  if (frame != NULL)
+    {
+      /* Cool, refound it.  */
+      select_frame (frame);
+      return;
+    }
 
-  if ((selected_frame_info = frame_find_by_id (a_frame_id)) != NULL)
+  /* Nothing else to do, the frame layout really changed.
+     Tell the user.  */
+  if (!ui_out_is_mi_like_p (uiout))
     {
-      select_frame (selected_frame_info);
+      warning (_("\
+Couldn't restore frame #%d in current thread, at reparsed frame #0\n"),
+	       frame_level);
+      /* For MI, we should probably have a notification about
+	 current frame change.  But this error is not very
+	 likely, so don't bother for now.  */
+      print_stack_frame (frame, 1, SRC_LINE);
     }
 }
 
@@ -784,31 +948,66 @@ struct current_thread_cleanup
 {
   ptid_t inferior_ptid;
   struct frame_id selected_frame_id;
+  int selected_frame_level;
+  int was_stopped;
 };
 
 static void
 do_restore_current_thread_cleanup (void *arg)
 {
+  struct thread_info *tp;
   struct current_thread_cleanup *old = arg;
   restore_current_thread (old->inferior_ptid);
 
-  /* A command like 'thread apply all $exec_command&' may change the
-     running state of the originally selected thread, so we have to
-     recheck it here.  */
-  if (!is_running (old->inferior_ptid))
-    restore_selected_frame (old->selected_frame_id);
+  /* The running state of the originally selected thread may have
+     changed, so we have to recheck it here.  */
+  if (old->was_stopped
+      && is_stopped (inferior_ptid)
+      && target_has_registers
+      && target_has_stack
+      && target_has_memory)
+    restore_selected_frame (old->selected_frame_id,
+			    old->selected_frame_level);
+}
+
+static void
+restore_current_thread_cleanup_dtor (void *arg)
+{
+  struct current_thread_cleanup *old = arg;
+  struct thread_info *tp;
+  tp = find_thread_pid (old->inferior_ptid);
+  if (tp)
+    tp->refcount--;
   xfree (old);
 }
 
 struct cleanup *
-make_cleanup_restore_current_thread (ptid_t inferior_ptid, 
-                                     struct frame_id a_frame_id)
+make_cleanup_restore_current_thread (void)
 {
-  struct current_thread_cleanup *old
-    = xmalloc (sizeof (struct current_thread_cleanup));
+  struct thread_info *tp;
+  struct frame_info *frame;
+  struct current_thread_cleanup *old;
+
+  old = xmalloc (sizeof (struct current_thread_cleanup));
   old->inferior_ptid = inferior_ptid;
-  old->selected_frame_id = a_frame_id;
-  return make_cleanup (do_restore_current_thread_cleanup, old);
+  old->was_stopped = is_stopped (inferior_ptid);
+  if (old->was_stopped
+      && target_has_registers
+      && target_has_stack
+      && target_has_memory)
+    frame = get_selected_frame (NULL);
+  else
+    frame = NULL;
+
+  old->selected_frame_id = get_frame_id (frame);
+  old->selected_frame_level = frame_relative_level (frame);
+
+  tp = find_thread_pid (inferior_ptid);
+  if (tp)
+    tp->refcount++;
+
+  return make_cleanup_dtor (do_restore_current_thread_cleanup, old,
+			    restore_current_thread_cleanup_dtor);
 }
 
 /* Apply a GDB command to a list of threads.  List syntax is a whitespace
@@ -824,27 +1023,17 @@ static void
 thread_apply_all_command (char *cmd, int from_tty)
 {
   struct thread_info *tp;
-  struct cleanup *old_chain = make_cleanup (null_cleanup, 0);
+  struct cleanup *old_chain;
   char *saved_cmd;
-  struct frame_id saved_frame_id;
-  ptid_t current_ptid;
-  int thread_has_changed = 0;
 
   if (cmd == NULL || *cmd == '\000')
     error (_("Please specify a command following the thread ID list"));
-  
-  current_ptid = inferior_ptid;
 
-  if (!is_running (inferior_ptid))
-    saved_frame_id = get_frame_id (get_selected_frame (NULL));
-  else
-    saved_frame_id = null_frame_id;
-  make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
-
-  /* It is safe to update the thread list now, before
-     traversing it for "thread apply all".  MVS */
+  prune_threads ();
   target_find_new_threads ();
 
+  old_chain = make_cleanup_restore_current_thread ();
+
   /* Save a copy of the command in case it is clobbered by
      execute_command */
   saved_cmd = xstrdup (cmd);
@@ -863,13 +1052,7 @@ thread_apply_all_command (char *cmd, int from_tty)
 	strcpy (cmd, saved_cmd);	/* Restore exact command used previously */
       }
 
-  if (!ptid_equal (current_ptid, inferior_ptid))
-    thread_has_changed = 1;
-
   do_cleanups (old_chain);
-  /* Print stack frame only if we changed thread.  */
-  if (thread_has_changed && !is_running (inferior_ptid))
-    print_stack_frame (get_current_frame (), 1, SRC_LINE);
 }
 
 static void
@@ -878,11 +1061,7 @@ thread_apply_command (char *tidlist, int from_tty)
   char *cmd;
   char *p;
   struct cleanup *old_chain;
-  struct cleanup *saved_cmd_cleanup_chain;
   char *saved_cmd;
-  struct frame_id saved_frame_id;
-  ptid_t current_ptid;
-  int thread_has_changed = 0;
 
   if (tidlist == NULL || *tidlist == '\000')
     error (_("Please specify a thread ID list"));
@@ -892,18 +1071,10 @@ thread_apply_command (char *tidlist, int from_tty)
   if (*cmd == '\000')
     error (_("Please specify a command following the thread ID list"));
 
-  current_ptid = inferior_ptid;
-
-  if (!is_running (inferior_ptid))
-    saved_frame_id = get_frame_id (get_selected_frame (NULL));
-  else
-    saved_frame_id = null_frame_id;
-  old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
-
   /* Save a copy of the command in case it is clobbered by
      execute_command */
   saved_cmd = xstrdup (cmd);
-  saved_cmd_cleanup_chain = make_cleanup (xfree, (void *) saved_cmd);
+  old_chain = make_cleanup (xfree, saved_cmd);
   while (tidlist < cmd)
     {
       struct thread_info *tp;
@@ -941,26 +1112,24 @@ thread_apply_command (char *tidlist, int from_tty)
 	    warning (_("Thread %d has terminated."), start);
 	  else
 	    {
+	      make_cleanup_restore_current_thread ();
+
 	      if (non_stop)
 		context_switch_to (tp->ptid);
 	      else
 		switch_to_thread (tp->ptid);
+
 	      printf_filtered (_("\nThread %d (%s):\n"), tp->num,
 			       target_tid_to_str (inferior_ptid));
 	      execute_command (cmd, from_tty);
-	      strcpy (cmd, saved_cmd);	/* Restore exact command used previously */
+
+	      /* Restore exact command used previously.  */
+	      strcpy (cmd, saved_cmd);
 	    }
 	}
     }
 
-  if (!ptid_equal (current_ptid, inferior_ptid))
-    thread_has_changed = 1;
-
-  do_cleanups (saved_cmd_cleanup_chain);
   do_cleanups (old_chain);
-  /* Print stack frame only if we changed thread.  */
-  if (thread_has_changed)
-    print_stack_frame (get_current_frame (), 1, SRC_LINE);
 }
 
 /* Switch to the specified thread.  Will dispatch off to thread_apply_command
@@ -971,11 +1140,17 @@ thread_command (char *tidstr, int from_tty)
 {
   if (!tidstr)
     {
-      /* Don't generate an error, just say which thread is current. */
       if (target_has_stack)
-	printf_filtered (_("[Current thread is %d (%s)]\n"),
-			 pid_to_thread_id (inferior_ptid),
-			 target_tid_to_str (inferior_ptid));
+	{
+	  if (is_exited (inferior_ptid))
+	    printf_filtered (_("[Current thread is %d (%s) (exited)]\n"),
+			     pid_to_thread_id (inferior_ptid),
+			     target_tid_to_str (inferior_ptid));
+	  else
+	    printf_filtered (_("[Current thread is %d (%s)]\n"),
+			     pid_to_thread_id (inferior_ptid),
+			     target_tid_to_str (inferior_ptid));
+	}
       else
 	error (_("No stack."));
       return;
@@ -1023,10 +1198,16 @@ do_captured_thread_select (struct ui_out *uiout, void *tidstr)
   ui_out_text (uiout, target_tid_to_str (inferior_ptid));
   ui_out_text (uiout, ")]");
 
-  if (!tp->running_)
-    print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
-  else
+  /* Note that we can't reach this with an exited thread, due to the
+     thread_alive check above.  */
+  if (tp->state_ == THREAD_RUNNING)
     ui_out_text (uiout, "(running)\n");
+  else
+    print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
+
+  /* Since the current thread may have changed, see if there is any
+     exited thread we can now delete.  */
+  prune_threads ();
 
   return GDB_RC_OK;
 }
@@ -1052,19 +1233,25 @@ _initialize_thread (void)
   c = add_info ("threads", info_threads_command,
 		_("IDs of currently known threads."));
   set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
 
   c = add_prefix_cmd ("thread", class_run, thread_command, _("\
 Use this command to switch between threads.\n\
 The new thread ID must be currently known."),
 		      &thread_cmd_list, "thread ", 1, &cmdlist);
   set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
 
-  add_prefix_cmd ("apply", class_run, thread_apply_command,
-		  _("Apply a command to a list of threads."),
-		  &thread_apply_list, "thread apply ", 1, &thread_cmd_list);
+  c = add_prefix_cmd ("apply", class_run, thread_apply_command,
+		      _("Apply a command to a list of threads."),
+		      &thread_apply_list, "thread apply ", 1, &thread_cmd_list);
+  set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
 
-  add_cmd ("all", class_run, thread_apply_all_command,
-	   _("Apply a command to all threads."), &thread_apply_list);
+  c = add_cmd ("all", class_run, thread_apply_all_command,
+	       _("Apply a command to all threads."), &thread_apply_list);
+  set_cmd_async_ok (c);
+  set_cmd_no_selected_thread_ok (c);
 
   if (!xdb_commands)
     add_com_alias ("t", "thread", class_run, 1);
diff --git a/gdb/top.c b/gdb/top.c
index fe4b1d0..86738e7 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -362,6 +362,8 @@ do_chdir_cleanup (void *old_dir)
 /* Execute the line P as a command.
    Pass FROM_TTY as second argument to the defining function.  */
 
+/* Execute command P, in the current user context.  */
+
 void
 execute_command (char *p, int from_tty)
 {
@@ -415,12 +417,19 @@ execute_command (char *p, int from_tty)
 
       c = lookup_cmd (&p, cmdlist, "", 0, 1);
 
-      /* If the target is running, we allow only a limited set of
-         commands. */
+      /* If the selected thread has terminated, we allow only a
+	 limited set of commands.  */
       if (target_can_async_p ()
-  	  && ((!non_stop && any_running ())
-  	      || (non_stop && is_running (inferior_ptid)))
-	  && !get_cmd_async_ok (c))
+	  && is_exited (inferior_ptid)
+	  && !get_cmd_no_selected_thread_ok (c))
+	error (_("\
+Cannot execute this command without a live selected thread.  See `help thread'."));
+      /* If the target is running, we allow only a limited set of
+	 commands.  */
+      else if (target_can_async_p ()
+	       && ((!non_stop && any_running ())
+		   || (non_stop && is_running (inferior_ptid)))
+	       && !get_cmd_async_ok (c))
 	error (_("Cannot execute this command while the target is running."));
 
       /* Pass null arg rather than an empty one.  */
diff --git a/gdb/utils.c b/gdb/utils.c
index cdea5a6..e1901d1 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -208,6 +208,14 @@ make_cleanup (make_cleanup_ftype *function, void *arg)
 }
 
 struct cleanup *
+make_cleanup_dtor (make_cleanup_ftype *function, void *arg,
+		   void (*dtor) (void *))
+{
+  return make_my_cleanup2 (&cleanup_chain,
+			   function, arg, dtor);
+}
+
+struct cleanup *
 make_final_cleanup (make_cleanup_ftype *function, void *arg)
 {
   return make_my_cleanup (&final_cleanup_chain, function, arg);
diff --git a/gdb/varobj.c b/gdb/varobj.c
index e94a35e..3a0bf5e 100644
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -2198,8 +2198,7 @@ c_value_of_root (struct varobj **var_handle)
     /* Not a root var */
     return NULL;
 
-  back_to = make_cleanup_restore_current_thread (
-    inferior_ptid, get_frame_id (deprecated_safe_get_selected_frame ()));
+  back_to = make_cleanup_restore_current_thread ();
 
   /* Determine whether the variable is still around. */
   if (var->root->valid_block == NULL || var->root->floating)