[Intel-gfx] [PATCH] drm/i915: Protect fbdev across slow or failed initialisation

[Gustav Fägerlind]

Cool, thank you.
I dont believe I can easily reproduce it, it has only happend few times
(and i reboot my lappy >2 times per day).

//
Gustav

2016-02-03 14:25 GMT+01:00 Lukas Wunner <lukas at wunner.de>:

> Hi,
>
> On Wed, Feb 03, 2016 at 09:17:37AM +0000, Chris Wilson wrote:
> > If the initialisation fails, we may be left with a dangling pointer with
> > an incomplete fbdev structure.
>
> This shouldn't happen with 4.5, the fbdev is now clobbered if
> initialization
> fails, the existing "if (dev_priv->fbdev)" checks should thus be
> sufficient.
> See 54632abe8ca3 ("drm/i915: Fix oops caused by fbdev initialization
> failure") as well as 366e39b4d2c5 ("drm/i915: Tear down fbdev if
> initialization fails").
>
> Gustav Fagerlind and Li Weinan both reported this for 4.3. It would be
> interesting to know if it can be reproduced at all with 4.5-rc2.
>
> Best regards,
>
> Lukas
>
> > Here we want to disable internal calls
> > into fbdev. Similarly, the initialisation may be slow and we haven't yet
> > enabled the fbdev (e.g. quick suspend or last-close before the async init
> > completes).
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93580
> > Reported-by: "Li, Weinan Z" <weinan.z.li at intel.com>
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > ---
> >  drivers/gpu/drm/i915/intel_fbdev.c | 41
> ++++++++++++++++++++++++--------------
> >  1 file changed, 26 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c
> b/drivers/gpu/drm/i915/intel_fbdev.c
> > index 09840f4380f9..6218bc5370a1 100644
> > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > @@ -114,6 +114,20 @@ static struct fb_ops intelfb_ops = {
> >       .fb_debug_leave = drm_fb_helper_debug_leave,
> >  };
> >
> > +static bool intel_fbdev_active(struct intel_fbdev *ifbdev)
> > +{
> > +     struct fb_info *info;
> > +
> > +     if (ifbdev == NULL)
> > +             return false;
> > +
> > +     info = ifbdev->helper.fbdev;
> > +     if (!info->screen_base)
> > +             return false;
> > +
> > +     return info->state == FBINFO_STATE_RUNNING;
> > +}
> > +
> >  static int intelfb_alloc(struct drm_fb_helper *helper,
> >                        struct drm_fb_helper_surface_size *sizes)
> >  {
> > @@ -753,6 +767,8 @@ void intel_fbdev_set_suspend(struct drm_device *dev,
> int state, bool synchronous
> >               return;
> >
> >       info = ifbdev->helper.fbdev;
> > +     if (!info->screen_base)
> > +             return;
> >
> >       if (synchronous) {
> >               /* Flush any pending work to turn the console on, and then
> > @@ -794,29 +810,24 @@ void intel_fbdev_set_suspend(struct drm_device
> *dev, int state, bool synchronous
> >
> >  void intel_fbdev_output_poll_changed(struct drm_device *dev)
> >  {
> > -     struct drm_i915_private *dev_priv = dev->dev_private;
> > -     if (dev_priv->fbdev)
> > +     struct drm_i915_private *dev_priv = to_i915(dev);
> > +
> > +     if (intel_fbdev_active(dev_priv->fbdev))
> >               drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
> >  }
> >
> >  void intel_fbdev_restore_mode(struct drm_device *dev)
> >  {
> > -     int ret;
> > -     struct drm_i915_private *dev_priv = dev->dev_private;
> > -     struct intel_fbdev *ifbdev = dev_priv->fbdev;
> > -     struct drm_fb_helper *fb_helper;
> > +     struct intel_fbdev *ifbdev = to_i915(dev)->fbdev;
> >
> > -     if (!ifbdev)
> > +     if (!intel_fbdev_active(ifbdev))
> >               return;
> >
> > -     fb_helper = &ifbdev->helper;
> > -
> > -     ret = drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper);
> > -     if (ret) {
> > -             DRM_DEBUG("failed to restore crtc mode\n");
> > -     } else {
> > -             mutex_lock(&fb_helper->dev->struct_mutex);
> > +     if (drm_fb_helper_restore_fbdev_mode_unlocked(&ifbdev->helper) ==
> 0) {
> > +             mutex_lock(&dev->struct_mutex);
> >               intel_fb_obj_invalidate(ifbdev->fb->obj, ORIGIN_GTT);
> > -             mutex_unlock(&fb_helper->dev->struct_mutex);
> > +             mutex_unlock(&dev->struct_mutex);
> > +     } else {
> > +             DRM_DEBUG("failed to restore crtc mode\n");
> >       }
> >  }
> > --
> > 2.7.0
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
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