A refcounting leak was found of the original frame buffer attached to
the CRTC when using the page_flip ioctl, resulting in the frame buffer
never being freed.
This was not obvious initially, as if the page flip subsequently
re-attaches the original frame buffer, the refcounts will be balanced.
However, if the original frame buffer is freed, then it will be leaked.
Fix this by ensuring that we take a reference on the incoming fb, but
rely on the queued work to drop that ref count.
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/armada/armada_crtc.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/armada/armada_crtc.c b/drivers/gpu/drm/armada/armada_crtc.c
index 1f0875c26dc5..ac2d73f4af45 100644
--- a/drivers/gpu/drm/armada/armada_crtc.c
+++ b/drivers/gpu/drm/armada/armada_crtc.c
@@ -945,18 +945,15 @@ static int armada_drm_crtc_page_flip(struct drm_crtc *crtc,
armada_reg_queue_end(work->regs, i);
/*
- * Hold the old framebuffer for the work - DRM appears to drop our
- * reference to the old framebuffer in drm_mode_page_flip_ioctl().
+ * Ensure that we hold a reference on the new framebuffer.
+ * This has to match the behaviour in mode_set.
*/
- drm_framebuffer_reference(work->old_fb);
+ drm_framebuffer_reference(fb);
ret = armada_drm_crtc_queue_frame_work(dcrtc, work);
if (ret) {
- /*
- * Undo our reference above; DRM does not drop the reference
- * to this object on error, so that's okay.
- */
- drm_framebuffer_unreference(work->old_fb);
+ /* Undo our reference above */
+ drm_framebuffer_unreference(fb);
kfree(work);
return ret;
}
--
1.8.3.1
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