Re: [PATCH][PR gdb/28874] gdb/remote: switch to added threads if there isn't one already

[Mikaela Szekely <qyriad@gmail.com>]

Is there anything specific that's blocking this patch from being
accepted? This is still an active bug in GDB.

On Sat, Jun 25, 2022 at 11:29 AM Mikaela Szekely
<mikaela.szekely@qyriad.me> wrote:
>
> Are there any thoughts on this? I'm happy to answer any questions if
> there are any.
>
> On Tue, Apr 19, 2022 at 4:01 PM Mikaela Szekely
> <mikaela.szekely@qyriad.me> wrote:
> >
> > Bug PR gdb/28874 reports a failed assertion when attaching to remote
> > targets. This assertion is checked after a call to
> > gdb::observers::new_thread.notify from set_running.
> > The call to set_running in remote_target::remote_add_thread, however,
> > appears to always be called before any call to switch_to_thread
> > for remote targets that have set non-stop off.
> >
> > This commit proposes a new internal function has_inferior_thread in
> > gdb/thread.c, which allows remote_target::remote_add_thread to check if
> > the current thread has been set or not. And thus I have also adjusted
> > the logic of ::remote_add_thread to call switch_to_thread upon thread
> > creation if has_inferior_thread returns false.
> >
> > Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28874
> > ---
> >  gdb/gdbthread.h | 3 +++
> >  gdb/remote.c    | 6 ++++++
> >  gdb/thread.c    | 7 +++++++
> >  3 files changed, 16 insertions(+)
> >
> > diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
> > index 1a33eb61221..bf230410a12 100644
> > --- a/gdb/gdbthread.h
> > +++ b/gdb/gdbthread.h
> > @@ -875,6 +875,9 @@ class scoped_restore_current_thread
> >    enum language m_lang;
> >  };
> >
> > +/* Returns true if there is a current inferior thread. */
> > +extern bool has_inferior_thread (void);
> > +
> >  /* Returns a pointer into the thread_info corresponding to
> >     INFERIOR_PTID.  INFERIOR_PTID *must* be in the thread list.  */
> >  extern struct thread_info* inferior_thread (void);
> > diff --git a/gdb/remote.c b/gdb/remote.c
> > index aa6a67a96e0..d35387650b3 100644
> > --- a/gdb/remote.c
> > +++ b/gdb/remote.c
> > @@ -2572,6 +2572,12 @@ remote_target::remote_add_thread (ptid_t ptid, bool running, bool executing,
> >    else
> >      thread = add_thread (this, ptid);
> >
> > +  /* If there isn't already an active thread, then switch to the
> > +     thread we just added, so bare-metal targets don't assert the
> > +     current thread as null. */
> > +  if (!has_inferior_thread())
> > +    switch_to_thread(thread);
> > +
> >    /* We start by assuming threads are resumed.  That state then gets updated
> >       when we process a matching stop reply.  */
> >    get_remote_thread_info (thread)->set_resumed ();
> > diff --git a/gdb/thread.c b/gdb/thread.c
> > index 9d0693bd0b8..e7b418b1c85 100644
> > --- a/gdb/thread.c
> > +++ b/gdb/thread.c
> > @@ -79,6 +79,13 @@ is_current_thread (const thread_info *thr)
> >    return thr == current_thread_;
> >  }
> >
> > +
> > +bool
> > +has_inferior_thread (void)
> > +{
> > +  return current_thread_ != nullptr;
> > +}
> > +
> >  struct thread_info*
> >  inferior_thread (void)
> >  {
> > --
> > 2.35.1
> >