[4/7] Fix handle_no_resumed w/ multiple targets

Message ID 20200706190252.22552-5-pedro@palves.net
State New
Headers show
  • GDB busy loop when interrupting non-stop program (PR 26199)
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Commit Message

Pedro Alves July 6, 2020, 7:02 p.m.
handle_no_resumed is currently not considering multiple targets.

Say you have two inferiors 1 and 2, each connected to a different
target, A and B.

Now say you set inferior 2 running, with "continue &".

Now you select a thread of inferior 1, say thread 1.2, and continue in
the foreground.  All other threads of inferior 1 are left stopped.
Thread 1.2 exits, and thus target A has no other resumed thread, so it

At this point, if both inferiors were running in the same target,
handle_no_resumed would realize that threads of inferior 2 are still
executing, so the TARGET_WAITKIND_NO_RESUMED event should be ignored.
But because handle_no_resumed only walks the threads of the current
target, it misses noticing that threads of inferior 2 are still
executing.  The fix is just to walk over all threads of all targets.

A testcase covering the use case above will be added in a following
patch.  It can't be added yet because it depends on yet another fix to
handle_no_resumed not included here.


	PR gdb/26199
	* infrun.c (handle_no_resumed): Handle multiple targets.
 gdb/infrun.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)



diff --git a/gdb/infrun.c b/gdb/infrun.c
index a01e0969cb..0f2f45a4d2 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -5068,16 +5068,28 @@  handle_no_resumed (struct execution_control_state *ecs)
      have resumed threads _now_.  In the example above, this removes
      thread 3 from the thread list.  If thread 2 was re-resumed, we
      ignore this event.  If we find no thread resumed, then we cancel
-     the synchronous command show "no unwaited-for " to the user.  */
-  update_thread_list ();
+     the synchronous command and show "no unwaited-for " to the
+     user.  */
+  {
+    scoped_restore_current_thread restore_thread;
+    for (auto *target : all_non_exited_process_targets ())
+      {
+	switch_to_target_no_thread (target);
+	update_thread_list ();
+      }
+  }
-  for (thread_info *thread : all_non_exited_threads (ecs->target))
+  for (thread_info *thread : all_non_exited_threads ())
       if (thread->executing
 	  || thread->suspend.waitstatus_pending_p)
-	  /* There were no unwaited-for children left in the target at
-	     some point, but there are now.  Just ignore.  */
+	  /* Either there were no unwaited-for children left in the
+	     target at some point, but there are now, or some target
+	     other than the eventing one has unwaited-for children
+	     left.  Just ignore.  */
 	  if (debug_infrun)
 	    fprintf_unfiltered (gdb_stdlog,