[PATCH] drm/radeon: fix oops in ttm reserve when pageflipping (v2) - dri-devel - freedesktop.org experimental mailing list

29 May 2011

From: Dave Airlie airlied@redhat.com
We need to take a reference to this object, pinning doesn't take a reference
so if userspace deletes the object it can disappear even if pinned.
v2: fix error paths to unreference properly also.
should fix:
https://bugzilla.kernel.org/show_bug.cgi?id=32402
and
https://bugzilla.redhat.com/show_bug.cgi?id=680651
Signed-off-by: Dave Airlie airlied@redhat.com
---
 drivers/gpu/drm/radeon/radeon_display.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index ae247ee..292f73f 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -264,6 +264,8 @@ static void radeon_unpin_work_func(struct work_struct *__work)
    	radeon_bo_unreserve(work->old_rbo);
    } else
    	DRM_ERROR("failed to reserve buffer after flip\n");
+
+	drm_gem_object_unreference_unlocked(&work->old_rbo->gem_base);
    kfree(work);
 }
@@ -371,6 +373,8 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
    new_radeon_fb = to_radeon_framebuffer(fb);
    /* schedule unpin of the old buffer */
    obj = old_radeon_fb->obj;
+	/* take a reference to the old object */
+	drm_gem_object_reference(obj);
    rbo = gem_to_radeon_bo(obj);
    work->old_rbo = rbo;
    INIT_WORK(&work->work, radeon_unpin_work_func);
@@ -378,12 +382,9 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
    /* We borrow the event spin lock for protecting unpin_work */
    spin_lock_irqsave(&dev->event_lock, flags);
    if (radeon_crtc->unpin_work) {
-		spin_unlock_irqrestore(&dev->event_lock, flags);
-		kfree(work);
-		radeon_fence_unref(&fence);
-
    	DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
-		return -EBUSY;
+		r = -EBUSY;
+		goto unlock_free;
    }
    radeon_crtc->unpin_work = work;
    radeon_crtc->deferred_flip_completion = 0;
@@ -497,6 +498,8 @@ pflip_cleanup1:
 pflip_cleanup:
    spin_lock_irqsave(&dev->event_lock, flags);
    radeon_crtc->unpin_work = NULL;
+unlock_free:
+	drm_gem_object_unreference_unlocked(old_radeon_fb->obj);
    spin_unlock_irqrestore(&dev->event_lock, flags);
    radeon_fence_unref(&fence);
    kfree(work);
-- 
1.7.4.4


    