Quoting Chris Wilson (2017-06-22 17:02:11)
> Commit fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer
> flushes") adds a dependency to ifbdev->vma when flushing the framebufer,
> but the checks are only against the existence of the ifbdev->fb and not
> against ifbdev->vma. This leaves a window of opportunity where we may
> try to operate on the fbdev prior to it being probed (thanks to
> asynchronous booting).
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101534
> Fixes: fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer flushes")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Ping?
> ---
> drivers/gpu/drm/i915/intel_fbdev.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index 03347c6ae599..0c4cde6b2e6f 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -535,13 +535,14 @@ static void intel_fbdev_destroy(struct intel_fbdev *ifbdev)
>
> drm_fb_helper_fini(&ifbdev->helper);
>
> - if (ifbdev->fb) {
> + if (ifbdev->vma) {
> mutex_lock(&ifbdev->helper.dev->struct_mutex);
> intel_unpin_fb_vma(ifbdev->vma);
> mutex_unlock(&ifbdev->helper.dev->struct_mutex);
> + }
>
> + if (ifbdev->fb)
> drm_framebuffer_remove(&ifbdev->fb->base);
> - }
>
> kfree(ifbdev);
> }
> @@ -765,7 +766,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
> struct intel_fbdev *ifbdev = dev_priv->fbdev;
> struct fb_info *info;
>
> - if (!ifbdev || !ifbdev->fb)
> + if (!ifbdev || !ifbdev->vma)
> return;
>
> info = ifbdev->helper.fbdev;
> @@ -812,7 +813,7 @@ void intel_fbdev_output_poll_changed(struct drm_device *dev)
> {
> struct intel_fbdev *ifbdev = to_i915(dev)->fbdev;
>
> - if (ifbdev && ifbdev->fb)
> + if (ifbdev && ifbdev->vma)
> drm_fb_helper_hotplug_event(&ifbdev->helper);
> }
>
> @@ -824,7 +825,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
> return;
>
> intel_fbdev_sync(ifbdev);
> - if (!ifbdev->fb)
> + if (!ifbdev->vma)
> return;
>
> if (drm_fb_helper_restore_fbdev_mode_unlocked(&ifbdev->helper) == 0)
> --
> 2.13.1
>
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