Initialize last_resume_kind for remote fork child
authorDon Breazeal <donb@codesourcery.com>
Thu, 28 May 2015 20:12:01 +0000 (13:12 -0700)
committerDon Breazeal <donb@codesourcery.com>
Thu, 28 May 2015 21:40:30 +0000 (14:40 -0700)
commitbfacd19d64c76b740a4a9c18dce4277e4a9afde5
tree3a5e1bf7d29a24851fa91bb2c16399580f12470e
parent8dd06f7a89b6eb7b646349f50746b3d2e85ed5de
Initialize last_resume_kind for remote fork child

This patch fixes some intermittent test failures in
gdb.base/foll-vfork.exp where a vfork child would be (incorrectly)
resumed when handling the vfork event.  In this case the result
was a subsequent event reported to the client side as a SIGTRAP
delivered to the as-yet-unknown child thread.

The new thread was resumed (incorrectly) in linux-low.c when
resume_stopped_resumed_lwps was called from
linux_wait_for_event_filtered after the vfork event had been
handled in handle_extended_wait.

Gdbserver/linux-low.c's add_thread function creates threads with
last_resume_kind == resume_continue by default.  This field is
used by resume_stopped_resumed_lwps to decide whether to perform
the resume:

static void
resume_stopped_resumed_lwps (struct inferior_list_entry *entry) {
  struct thread_info *thread = (struct thread_info *) entry;
  struct lwp_info *lp = get_thread_lwp (thread);

  if (lp->stopped
      && !lp->status_pending_p
      && thread->last_resume_kind != resume_stop
      && thread->last_status.kind == TARGET_WAITKIND_IGNORE)
    {

So the fix is to make sure to set thread->last_resume_kind to
resume_stop.  Here we do that for new fork children in
gdbserver/linux-low.c:handle_extended_wait.

In addition, it seemed prudent to initialize lwp_info.status_pending_p
for the new fork child.  I also rearranged the initialization code
so that all of the lwp_info initialization was together, rather than
intermixed with thread_info and process_info initialization.

Tested native, native-gdbserver, native-extended-gdbserver on
x86_64 GNU/Linux.

gdb/gdbserver/

* linux-low.c (handle_extended_wait): Initialize
thread_info.last_resume_kind for new fork children.
gdb/gdbserver/ChangeLog
gdb/gdbserver/linux-low.c