Re: [RFC] persistence of schedlock mode

[Mark Kettenis <mark dot kettenis at xs4all dot nl>]

> Date: Wed, 12 May 2010 11:08:48 -0700
> From: Michael Snyder <msnyder@vmware.com>
> 
> Bug 11580 points out a problem related to persistence of the
> scheduler locking mode.  If you set the mode to "on" (which
> means that only one thread can run), and then kill and restart
> your program, the mode persists and your program may deadlock.
> 
> I don't think this is a problem for mode "step", and it could
> be argued that mode "on" is "use at your own risk".  However
> I've been thinking about how to resolve it, and this simple
> but intrusive patch is what I come up with.
> 
> Comments?

Ah, that's clever.  The user will be notified, but doesn't have to
answer an additional question.

> Index: infrun.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/infrun.c,v
> retrieving revision 1.438
> diff -u -p -r1.438 infrun.c
> --- infrun.c	6 May 2010 19:14:08 -0000	1.438
> +++ infrun.c	12 May 2010 17:37:09 -0000
> @@ -1416,6 +1416,18 @@ set_schedlock_func (char *args, int from
>      }
>  }
>  
> +/* reset_schedlock -- public */
> + 
> +void
> +reset_schedlock ()
> +{
> +  if (scheduler_mode == schedlock_on)
> +    {
> +      warning ("Resetting scheduler-lock mode to 'off'");
> +      scheduler_mode = schedlock_off;
> +    }
> +}
> +
>  /* True if execution commands resume all threads of all processes by
>     default; otherwise, resume only threads of the current inferior
>     process.  */
> Index: target.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/target.c,v
> retrieving revision 1.250
> diff -u -p -r1.250 target.c
> --- target.c	6 May 2010 22:29:49 -0000	1.250
> +++ target.c	12 May 2010 17:37:09 -0000
> @@ -2231,6 +2231,10 @@ void
>  target_mourn_inferior (void)
>  {
>    struct target_ops *t;
> +
> +  /* Clear schedlock in infrun.c */
> +  reset_schedlock ();
> +
>    for (t = current_target.beneath; t != NULL; t = t->beneath)
>      {
>        if (t->to_mourn_inferior != NULL)