From: Simon Marchi <simon.marchi@efficios.com>
Date: Mon, 16 Mar 2020 21:21:55 +0000 (-0400)
Subject: gdb: stop trying to prepare displaced steps for an inferior when it returns _UNAVAILABLE
X-Git-Url: http://git.efficios.com/?p=deliverable%2Fbinutils-gdb.git;a=commitdiff_plain;h=d6864985e9af77d15e7310b1066543eb8bdc5bba

gdb: stop trying to prepare displaced steps for an inferior when it returns _UNAVAILABLE

Once we got one _UNAVAILABLE for a given inferior, don't try to prepare
other threads for displaced stepping for that inferior during this
execution of start_step_over.
---

diff --git a/gdb/displaced-stepping.h b/gdb/displaced-stepping.h
index 0cb2d8c970..835fd92086 100644
--- a/gdb/displaced-stepping.h
+++ b/gdb/displaced-stepping.h
@@ -67,6 +67,8 @@ struct displaced_step_inferior_state
   /* True if preparing a displaced step ever failed.  If so, we won't
      try displaced stepping for this inferior again.  */
   bool failed_before;
+
+  bool unavailable = false;
 };
 
 /* Per-thread displaced stepping state.  */
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 17c342be50..ec06e5703b 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -1748,6 +1748,7 @@ displaced_step_prepare_throw (thread_info *tp)
 			    target_pid_to_str (tp->ptid).c_str ());
 
       global_thread_step_over_chain_enqueue (tp);
+      tp->inf->displaced_step_state.unavailable = true;
 
       return DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE;
     }
@@ -1937,6 +1938,9 @@ start_step_over (void)
 			"infrun: stealing list of %d threads to step from global queue\n",
 			thread_step_over_chain_length (threads_to_step));
 
+  for (inferior *inf : all_inferiors ())
+    inf->displaced_step_state.unavailable = false;
+
   for (tp = threads_to_step; tp != NULL; tp = next)
     {
       struct execution_control_state ecss;
@@ -1986,6 +1990,12 @@ start_step_over (void)
       if (!target_is_non_stop_p () && !step_what)
 	continue;
 
+      if (tp->inf->displaced_step_state.unavailable)
+	{
+	  global_thread_step_over_chain_enqueue (tp);
+	  continue;
+	}
+
       switch_to_thread (tp);
       reset_ecs (ecs, tp);
       keep_going_pass_signal (ecs);