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Re: [RFC] persistence of schedlock mode
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: msnyder at vmware dot com
- Cc: gdb-patches at sourceware dot org
- Date: Wed, 12 May 2010 21:25:09 +0200 (CEST)
- Subject: Re: [RFC] persistence of schedlock mode
- References: <4BEAEEB0.5040202@vmware.com>
> 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)