[Intel-gfx] [PATCH] drm/i915/execlists: Set priority hint prior to submission

[Chris Wilson]

Quoting Chris Wilson (2019-08-21 15:23:36)
> Since we now run process_csb() outside of the engine->active.lock, we
> can process a CS-event immediately upon our ELSP write. As we currently
> inspect the pending queue *after* the ELSP write, there is an
> opportunity for a CS-event to update the pending queue before we can
> read it, making ourselves chases an invalid pointer.
> 

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111427
> Fixes: df403069029d ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_lrc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index 44780e7fafec..d42584439f51 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -1335,9 +1335,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
>         if (submit) {
>                 *port = execlists_schedule_in(last, port - execlists->pending);
>                 memset(port + 1, 0, (last_port - port) * sizeof(*port));
> -               execlists_submit_ports(engine);
>                 execlists->switch_priority_hint =
>                         switch_prio(engine, *execlists->pending);
> +               execlists_submit_ports(engine);
>         } else {
>                 ring_set_paused(engine, 0);
>         }
> -- 
> 2.23.0.rc1
>