[PATCH v3 29/29] Add pending stop support to gdbserver's Windows port

Tom Tromey
2020-03-13T19:09:07Z

This changes gdbserver to also handle pending stops, the same way that
gdb does. This is PR gdb/22992.

gdbserver/ChangeLog
2020-03-13 Tom Tromey <tromey@adacore.com>

PR gdb/22992
* win32-low.c (child_continue): Call matching_pending_stop.
(get_child_debug_event): Call fetch_pending_stop. Push pending
stop when needed.
---
gdbserver/ChangeLog | 7 +++++++
gdbserver/win32-low.cc | 34 +++++++++++++++++++++++++++++++---
2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/gdbserver/win32-low.cc b/gdbserver/win32-low.cc
index 4312bb3ab7c..e1226b4b0db 100644
--- a/gdbserver/win32-low.cc
+++ b/gdbserver/win32-low.cc
@@ -430,6 +430,10 @@ continue_one_thread (thread_info *thread, int thread_id)
static BOOL
child_continue (DWORD continue_status, int thread_id)
{
+ desired_stop_thread_id = thread_id;
+ if (matching_pending_stop (debug_threads))
+ return TRUE;
+
/* The inferior will only continue after the ContinueDebugEvent
call. */
for_each_thread ([&] (thread_info *thread)
@@ -1274,6 +1278,16 @@ get_child_debug_event (DWORD *continue_status,
else
#endif
{
+ gdb::optional<pending_stop> stop = fetch_pending_stop (debug_threads);
+ if (stop.has_value ())
+ {
+ *ourstatus = stop->status;
+ current_event = stop->event;
+ ptid = debug_event_ptid (&current_event);
+ current_thread = find_thread_ptid (ptid);
+ return 1;
+ }
+
/* Keep the wait time low enough for comfortable remote
interruption, but high enough so gdbserver doesn't become a
bottleneck. */
@@ -1377,7 +1391,7 @@ get_child_debug_event (DWORD *continue_status,
ourstatus->value.sig = gdb_signal_from_host (exit_signal);
}
}
- child_continue (DBG_CONTINUE, -1);
+ child_continue (DBG_CONTINUE, desired_stop_thread_id);
CloseHandle (current_process_handle);
current_process_handle = NULL;
break;
@@ -1437,7 +1451,21 @@ get_child_debug_event (DWORD *continue_status,
}

ptid = debug_event_ptid (&current_event);
- current_thread = find_thread_ptid (ptid);
+
+ if (desired_stop_thread_id != -1 && desired_stop_thread_id != ptid.lwp ())
+ {
+ /* Pending stop. See the comment by the definition of
+ "pending_stops" for details on why this is needed. */
+ OUTMSG2 (("get_windows_debug_event - "
+ "unexpected stop in 0x%x (expecting 0x%x)\n",
+ ptid.lwp (), desired_stop_thread_id));
+ maybe_adjust_pc ();
+ pending_stops.push_back ({(DWORD) ptid.lwp (), *ourstatus, current_event});
+ ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
+ }
+ else
+ current_thread = find_thread_ptid (ptid);
+
return 1;
}

@@ -1486,7 +1514,7 @@ win32_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus,
/* fall-through */
case TARGET_WAITKIND_SPURIOUS:
/* do nothing, just continue */
- child_continue (continue_status, -1);
+ child_continue (continue_status, desired_stop_thread_id);
break;
}
}
--
2.21.1