From fdb1f0881318c83d9db836c9558c33407aca173e Mon Sep 17 00:00:00 2001
From: Pedro Alves <pedro@palves.net>
Date: Wed, 19 Feb 2025 14:37:39 +0000
Subject: [PATCH 1/2] init_wait_for_inferior doesn't imply proceed

The next patch adds an assertion to clear_proceed_status_thread,
making sure that we don't try to proceed a thread that is already
running.  Turns out that catches attach_command calling
init_wait_for_inferior too late, after attaching has already created
already-running threads.  This patch fixes.

However, that alone changes MI output when attaching (as caught by
e.g. gdb.rocm/mi-attach.exp).  We'd go from:

 -target-attach 2468587
 =thread-group-started,id="i1",pid="2468587"
 =thread-created,id="1",group-id="i1"
 ^done

to:

 -target-attach 2443288
 =thread-group-started,id="i1",pid="2443288"
 =thread-created,id="1",group-id="i1"
 =thread-created,id="2",group-id="i1"
 ~"[New LWP 2443317 (id 2)]\n"
 ^running
 *running,thread-id="2"
 (gdb)

That change would happen because init_wait_for_inferior calls
clear_proceed_status, which calls notify_about_to_proceed, where we
end up in mi_interp::on_about_to_proceed(), setting the mi_proceeded
flag.  If that happens before linux_nat_target::attach is called, then
the set_running calls inside linux_nat_target::attach result in
emiting ^running in MI instead of ^done due to the back-compatibility
hack in mi_on_resume_1.

Now, init_wait_inferior really does not imply we're about to call
proceed.  So restore the MI output by adding a new parameter to
clear_proceed_status that lets init_wait_inferior tell
clear_proceed_status to skip notifying the about_to_proceed observers.

I audited all init_wait_inferior calls, and this made sense in all of
them.  The places do call proceed after init_wait_inferior, already
explicitly clear_proceed_status after init_wait_inferior.  E.g.,
run_command_1.

Tested on x86_64-linux-gnu, native and gdbserver.

Change-Id: I4f5097d68f4694d44e1ae23fea3e9bce45fb078c
commit-id:123f9020
---
 gdb/infcmd.c | 8 ++++----
 gdb/infrun.c | 7 ++++---
 gdb/infrun.h | 5 +++--
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 98b45f884b1..2be2f4376c0 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -2862,6 +2862,10 @@ attach_command (const char *args, int from_tty)
      this function should probably be moved into target_pre_inferior.  */
   target_pre_inferior ();
 
+  /* Set up execution context to know that we should return from
+     wait_for_inferior as soon as the target reports a stop.  */
+  init_wait_for_inferior ();
+
   gdb::unique_xmalloc_ptr<char> stripped = strip_bg_char (args, &async_exec);
   args = stripped.get ();
 
@@ -2904,10 +2908,6 @@ attach_command (const char *args, int from_tty)
        finished.  */
   target_terminal::inferior ();
 
-  /* Set up execution context to know that we should return from
-     wait_for_inferior as soon as the target reports a stop.  */
-  init_wait_for_inferior ();
-
   inferior->needs_setup = true;
 
   if (target_is_non_stop_p ())
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 2e53d2a6c30..a6b5db3edd5 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -3123,7 +3123,7 @@ notify_about_to_proceed ()
 }
 
 void
-clear_proceed_status (int step)
+clear_proceed_status (int step, bool about_to_proceed)
 {
   /* With scheduler-locking replay, stop replaying other threads in the
      same process if we're not replaying the selected thread.
@@ -3162,7 +3162,8 @@ clear_proceed_status (int step)
       inferior->control.stop_soon = NO_STOP_QUIETLY;
     }
 
-  notify_about_to_proceed ();
+  if (about_to_proceed)
+    notify_about_to_proceed ();
 }
 
 /* Returns true if TP is still stopped at a breakpoint that needs
@@ -3851,7 +3852,7 @@ init_wait_for_inferior (void)
 
   breakpoint_init_inferior (current_inferior (), inf_starting);
 
-  clear_proceed_status (0);
+  clear_proceed_status (0, false);
 
   nullify_last_target_wait_ptid ();
 
diff --git a/gdb/infrun.h b/gdb/infrun.h
index 7e2b652e4f1..9eaa5387ef0 100644
--- a/gdb/infrun.h
+++ b/gdb/infrun.h
@@ -129,8 +129,9 @@ extern void start_remote (int from_tty);
 /* Clear out all variables saying what to do when inferior is
    continued or stepped.  First do this, then set the ones you want,
    then call `proceed'.  STEP indicates whether we're preparing for a
-   step/stepi command.  */
-extern void clear_proceed_status (int step);
+   step/stepi command.  Set ABOUT_TO_PROCEED to false if we're not
+   calling `proceeed` yet.  */
+extern void clear_proceed_status (int step, bool about_to_proceed = true);
 
 extern void proceed (CORE_ADDR, enum gdb_signal);
 

base-commit: 73434094ad8a861fe555045804e943d186ff6879
-- 
2.53.0