[PATCH] Fix for GDB failing to interrupt after run when no PID issued by stub

Omair Javaid
2018-01-29T10:44:56Z

This behaviour was observed with OpenOCD GDB stub where gdb was failing to stop when interrupted after issuing run command that does not preceede a continue.

Bug report can be found here: https://bugs.launchpad.net/gcc-arm-embedded/+bug/1594341

Here are the steps to reproduce:
1) arm-none-eabi-gdb file-to-debug.elf
2) target remote :3333
At this stage gdb would have connected and halted successfully.
3) run
Issue ctrl + C to interrupt running program and GDB wont be able to stop.

The reason narrowed down to be a case where gdb was unable to clear stop_soon to NO_STOP_QUIETLY;
As some gdb stubs dont report a PID in stop reply the inferior_ptid stays null. A call to remote_current_thread may assign a magic PID in that case.
Based on inferior_ptid function inferior_clear_proceed_status updates inferior->control.stop_soon = NO_STOP_QUIETLY;
If extended_remote_create_inferior calls inferior_clear_proceed_status before a magic PID is assigned to current inferior then it will fail to set inferior->control.stop_soon = NO_STOP_QUIETLY;

This patch adjusts call to inferior_clear_proceed_status such that a PID is assigned to inferior before we try to update inferior->control.stop_soon.

gdb/ChangeLog:
2018-01-29 Omair Javaid <omair.javaid@linaro.org>

* remote.c: (extended_remote_create_inferior): Adjust call to
inferior_clear_proceed_status.
---
gdb/remote.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index 5ac84df..3387e1c 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -9688,13 +9688,16 @@ Remote replied unexpectedly while setting startup-with-shell: %s"),
running again. This will mark breakpoints uninserted, and
get_offsets may insert breakpoints. */
init_thread_list ();
- init_wait_for_inferior ();
}

/* vRun's success return is a stop reply. */
stop_reply = run_worked ? rs->buf : NULL;
add_current_inferior_and_thread (stop_reply);

+ /* We have called add_current_inferior_and_thread above,
+ call init_wait_for_inferior before new inferior begins. */
+ init_wait_for_inferior ();
+
/* Get updated offsets, if the stub uses qOffsets. */
get_offsets ();
}
--
2.7.4