[PATCH v4 12/44] gdb, remote: do 'remote_add_inferior' in 'remote_notice_new_inferior' earlier

From: Tankut Baris Aktemur <[email protected]>

In remote_target::remote_notice_new_inferior, we check if the inferior
for the reported ptid exists, and if not, we add that inferior via
'remote_add_inferior'.  However, before adding the new inferior, we
may have already added a new thread, because the thread is not found
via 'in_thread_list'.  This may bring the odd situation that a new
thread is being added before its inferior exists.  Fix this problem by
moving the check and creation of a new inferior to an earlier spot in
the execution flow.

Note that the code has a check for inferior_ptid.is_pid, but this is
not useful to avoid the problem described above because the core
infrun clears inferior_ptid (i.e. sets to null_ptid) before waiting on
targets for stop events.
---
 gdb/remote.c | 35 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index 194c4cbd9bb..05cda9d0b0c 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -3223,6 +3223,23 @@ remote_target::remote_notice_new_inferior (ptid_t currthread,
       struct inferior *inf = NULL;
       int pid = currthread.pid ();
 
+      /* When connecting to a target remote, or to a target
+	 extended-remote which already was debugging an inferior, we
+	 may not know about it yet.  Add it before adding its child
+	 thread, so notifications are emitted in a sensible order.  */
+      if (find_inferior_pid (this, pid) == nullptr)
+	{
+	  bool fake_pid_p = !m_features.remote_multi_process_p ();
+
+	  inf = remote_add_inferior (fake_pid_p, pid, -1, 1);
+
+	  /* Fetch the target description for this inferior.  Make sure to
+	     leave the currently selected inferior unchanged.  */
+	  scoped_restore_current_thread restore_thread;
+	  switch_to_inferior_no_thread (inf);
+	  target_find_description ();
+	}
+
       if (inferior_ptid.is_pid ()
 	  && pid == inferior_ptid.pid ())
 	{
@@ -3253,24 +3270,6 @@ remote_target::remote_notice_new_inferior (ptid_t currthread,
 	  return;
 	}
 
-      /* When connecting to a target remote, or to a target
-	 extended-remote which already was debugging an inferior, we
-	 may not know about it yet.  Add it before adding its child
-	 thread, so notifications are emitted in a sensible order.  */
-      if (find_inferior_pid (this, currthread.pid ()) == NULL)
-	{
-	  bool fake_pid_p = !m_features.remote_multi_process_p ();
-
-	  inf = remote_add_inferior (fake_pid_p,
-				     currthread.pid (), -1, 1);
-
-	  /* Fetch the target description for this inferior.  Make sure to
-	     leave the currently selected inferior unchanged.  */
-	  scoped_restore_current_thread restore_thread;
-	  switch_to_inferior_no_thread (inf);
-	  target_find_description ();
-	}
-
       /* This is really a new thread.  Add it.  */
       thread_info *new_thr
 	= remote_add_thread (currthread, state, internal_state, false);
-- 
2.43.0

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