[v2,00/23] All-stop on top of non-stop

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 4dd25d6..334d153 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -4154,6 +4154,82 @@  switch_to_thread_cleanup (void *ptid_p)
   switch_to_thread (ptid);
 }
 
+/* Save the thread's event and stop reason to process it later.  */
+
+static void
+save_waitstatus (struct thread_info *tp, struct target_waitstatus *ws)
+{
+  struct regcache *regcache;
+  struct address_space *aspace;
+
+  if (debug_infrun)
+    {
+      char *statstr;
+
+      statstr = target_waitstatus_to_string (ws);
+      fprintf_unfiltered (gdb_stdlog,
+			  "infrun: saving status %s for %d.%ld.%ld\n",
+			  statstr,
+			  ptid_get_pid (tp->ptid),
+			  ptid_get_lwp (tp->ptid),
+			  ptid_get_tid (tp->ptid));
+      xfree (statstr);
+    }
+
+  /* Record for later.  */
+  tp->suspend.waitstatus = *ws;
+  tp->suspend.waitstatus_pending_p = 1;
+
+  regcache = get_thread_regcache (tp->ptid);
+  aspace = get_regcache_aspace (regcache);
+
+  if (ws->kind == TARGET_WAITKIND_STOPPED
+      && ws->value.sig == GDB_SIGNAL_TRAP)
+    {
+      CORE_ADDR pc = regcache_read_pc (regcache);
+
+      adjust_pc_after_break (tp, &tp->suspend.waitstatus);
+
+      if (thread_stopped_by_watchpoint (tp->ptid))
+	{
+	  tp->suspend.stop_reason
+	    = TARGET_STOPPED_BY_WATCHPOINT;
+	}
+      else if (target_supports_stopped_by_sw_breakpoint ()
+	       && thread_stopped_by_sw_breakpoint (tp->ptid))
+	{
+	  tp->suspend.stop_reason
+	    = TARGET_STOPPED_BY_SW_BREAKPOINT;
+	}
+      else if (target_supports_stopped_by_hw_breakpoint ()
+	       && thread_stopped_by_hw_breakpoint (tp->ptid))
+	{
+	  tp->suspend.stop_reason
+	    = TARGET_STOPPED_BY_HW_BREAKPOINT;
+	}
+      else if (!target_supports_stopped_by_hw_breakpoint ()
+	       && hardware_breakpoint_inserted_here_p (aspace,
+						       pc))
+	{
+	  tp->suspend.stop_reason
+	    = TARGET_STOPPED_BY_HW_BREAKPOINT;
+	}
+      else if (!target_supports_stopped_by_sw_breakpoint ()
+	       && software_breakpoint_inserted_here_p (aspace,
+						       pc))
+	{
+	  tp->suspend.stop_reason
+	    = TARGET_STOPPED_BY_SW_BREAKPOINT;
+	}
+      else if (!thread_has_single_step_breakpoints_set (tp)
+	       && currently_stepping (tp))
+	{
+	  tp->suspend.stop_reason
+	    = TARGET_STOPPED_BY_SINGLE_STEP;
+	}
+    }
+}
+
 /* Stop all threads.  */
 
 static void
@@ -4317,61 +4393,11 @@  stop_all_threads (void)
 		    }
 
 		  /* Record for later.  */
-		  t->suspend.waitstatus = ws;
-		  t->suspend.waitstatus_pending_p = 1;
+		  save_waitstatus (t, &ws);
 
 		  sig = (ws.kind == TARGET_WAITKIND_STOPPED
 			 ? ws.value.sig : GDB_SIGNAL_0);
 
-		  regcache = get_thread_regcache (t->ptid);
-		  aspace = get_regcache_aspace (regcache);
-
-		  if (ws.kind == TARGET_WAITKIND_STOPPED
-		      && ws.value.sig == GDB_SIGNAL_TRAP)
-		    {
-		      CORE_ADDR pc = regcache_read_pc (regcache);
-
-		      adjust_pc_after_break (t, &t->suspend.waitstatus);
-
-		      if (thread_stopped_by_watchpoint (t->ptid))
-			{
-			  t->suspend.stop_reason
-			    = TARGET_STOPPED_BY_WATCHPOINT;
-			}
-		      else if (target_supports_stopped_by_sw_breakpoint ()
-			       && thread_stopped_by_sw_breakpoint (t->ptid))
-			{
-			  t->suspend.stop_reason
-			    = TARGET_STOPPED_BY_SW_BREAKPOINT;
-			}
-		      else if (target_supports_stopped_by_hw_breakpoint ()
-			       && thread_stopped_by_hw_breakpoint (t->ptid))
-			{
-			  t->suspend.stop_reason
-			    = TARGET_STOPPED_BY_HW_BREAKPOINT;
-			}
-		      else if (!target_supports_stopped_by_hw_breakpoint ()
-			       && hardware_breakpoint_inserted_here_p (aspace,
-								       pc))
-			{
-			  t->suspend.stop_reason
-			    = TARGET_STOPPED_BY_HW_BREAKPOINT;
-			}
-		      else if (!target_supports_stopped_by_sw_breakpoint ()
-			       && software_breakpoint_inserted_here_p (aspace,
-								       pc))
-			{
-			  t->suspend.stop_reason
-			    = TARGET_STOPPED_BY_SW_BREAKPOINT;
-			}
-		      else if (!thread_has_single_step_breakpoints_set (t)
-			       && currently_stepping (t))
-			{
-			  t->suspend.stop_reason
-			    = TARGET_STOPPED_BY_SINGLE_STEP;
-			}
-		    }
-
 		  if (displaced_step_fixup (t->ptid, sig) < 0)
 		    {
 		      /* Add it back to the step-over queue.  */
@@ -4379,6 +4405,7 @@  stop_all_threads (void)
 		      thread_step_over_chain_enqueue (t);
 		    }
 
+		  regcache = get_thread_regcache (t->ptid);
 		  t->suspend.stop_pc = regcache_read_pc (regcache);
 
 		  if (debug_infrun)
@@ -5033,7 +5060,13 @@  restart_threads (struct thread_info *event_thread)
       /* If some thread needs to start a step-over at this point, it
 	 should still be in the step-over queue, and thus skipped
 	 above.  */
-      gdb_assert (!thread_still_needs_step_over (tp));
+      if (thread_still_needs_step_over (tp))
+	{
+	  internal_error (__FILE__, __LINE__,
+			  "thread [%s] needs a step-over, but not in "
+			  "step-over queue\n",
+			  target_pid_to_str (tp->ptid));
+	}
 
       if (currently_stepping (tp))
 	{
@@ -5056,10 +5089,24 @@  restart_threads (struct thread_info *event_thread)
     }
 }
 
+/* Callback for iterate_over_threads.  Find a resumed thread that has
+   a pending waitstatus.  */
+
+static int
+resumed_thread_with_pending_status (struct thread_info *tp,
+				    void *arg)
+{
+  return (tp->resumed
+	  && tp->suspend.waitstatus_pending_p);
+}
+
 /* Called when we get an event that may finish an in-line or
-   out-of-line (displaced stepping) step-over started previously.  */
+   out-of-line (displaced stepping) step-over started previously.
+   Return true if the event is processed and we should go back to the
+   event loop; false if the caller should continue processing the
+   event.  */
 
-static void
+static int
 finish_step_over (struct execution_control_state *ecs)
 {
   int had_step_over_info;
@@ -5081,7 +5128,7 @@  finish_step_over (struct execution_control_state *ecs)
     }
 
   if (!target_is_non_stop_p ())
-    return;
+    return 0;
 
   /* Start a new step-over in another thread if there's one that
      needs it.  */
@@ -5094,10 +5141,67 @@  finish_step_over (struct execution_control_state *ecs)
      these other threads stop.  */
   if (had_step_over_info && !step_over_info_valid_p ())
     {
+      struct thread_info *pending;
+
       restart_threads (ecs->event_thread);
 
-      gdb_assert (!ecs->event_thread->resumed);
+      /* If we have events pending, go through handle_inferior_event
+	 again, picking up a pending event at random.  This avoids
+	 thread starvation.  */
+      pending = iterate_over_threads (resumed_thread_with_pending_status,
+				      NULL);
+      if (pending != NULL)
+	{
+	  struct thread_info *tp = ecs->event_thread;
+	  struct regcache *regcache;
+
+	  if (debug_infrun)
+	    {
+	      fprintf_unfiltered (gdb_stdlog,
+				  "infrun: found resumed threads with "
+				  "pending events, saving status\n");
+	    }
+
+	  gdb_assert (pending != tp);
+
+	  /* Record the event thread's event for later.  */
+	  save_waitstatus (tp, &ecs->ws);
+	  /* This was cleared early, by handle_inferior_event.  Set it
+	     so this pending event is considered by
+	     do_target_wait.  */
+	  tp->resumed = 1;
+
+	  gdb_assert (!tp->executing);
+
+	  regcache = get_thread_regcache (tp->ptid);
+	  tp->suspend.stop_pc = regcache_read_pc (regcache);
+
+	  if (debug_infrun)
+	    {
+	      fprintf_unfiltered (gdb_stdlog,
+				  "infrun: saved stop_pc=%s for %s "
+				  "(currently_stepping=%d)\n",
+				  paddress (target_gdbarch (),
+					    tp->suspend.stop_pc),
+				  target_pid_to_str (tp->ptid),
+				  currently_stepping (tp));
+	    }
+
+	  /* This in-line step-over finished; clear this so we won't
+	     start a new one.  This is what handle_signal_stop would
+	     do, if we returned false.  */
+	  tp->stepping_over_breakpoint = 0;
+	  tp->stepping_over_watchpoint = 0;
+
+	  /* Wake up the event loop again.  */
+	  mark_async_event_handler (infrun_async_inferior_event_token);
+
+	  prepare_to_wait (ecs);
+	  return 1;
+	}
     }
+
+  return 0;
 }
 
 /* Come here when the program has stopped with a signal.  */
@@ -5116,7 +5220,8 @@  handle_signal_stop (struct execution_control_state *ecs)
   /* Do we need to clean up the state of a thread that has
      completed a displaced single-step?  (Doing so usually affects
      the PC, so do it here, before we set stop_pc.)  */
-  finish_step_over (ecs);
+  if (finish_step_over (ecs))
+    return;
 
   /* If we either finished a single-step or hit a breakpoint, but
      the user wanted this thread to be stopped, pretend we got a