On 22/06/2017 17:02, Chris Wilson wrote:
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).
How about changing the intelfb_alloc to not write the fb to ifbdev but
instead return it to the caller, so intelfb_create could then set the
ifbdev->fb and ifbdev->vma atomically under the mutex?
Regards,
Tvrtko
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>
---
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)
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