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    SubjectRe: [PATCH v6 2/2] drm: Prevent release fb after cleanup mode config
    On Mon, Apr 10, 2017 at 06:00:45PM +0800, Jeffy Chen wrote:
    > After unbinding drm, the user space may still owns the drm dev fd,
    > and may trigger fb release after cleanup mode config.
    >
    > Add a sanity check to prevent that.
    >
    > Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
    > ---
    >
    > Changes in v6: None
    > Changes in v5: None
    > Changes in v2: None
    >
    > drivers/gpu/drm/drm_framebuffer.c | 5 +++++
    > 1 file changed, 5 insertions(+)
    >
    > diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
    > index e8f9c13..03c1632 100644
    > --- a/drivers/gpu/drm/drm_framebuffer.c
    > +++ b/drivers/gpu/drm/drm_framebuffer.c
    > @@ -583,6 +583,11 @@ void drm_fb_release(struct drm_file *priv)
    > {
    > struct drm_framebuffer *fb, *tfb;
    > struct drm_mode_rmfb_work arg;
    > + struct drm_minor *minor = priv->minor;
    > + struct drm_device *dev = minor->dev;
    > +
    > + if (WARN_ON(!dev->mode_config.num_fb && !list_empty(&priv->fbs)))

    Have you actually seen this happen? num_fb should be tightly couple to
    priv->fbs, so it seems like this could only result from a driver bug (or I'm not
    reading the code correctly).

    Sean

    > + return;
    >
    > INIT_LIST_HEAD(&arg.fbs);
    >
    > --
    > 2.1.4
    >

    --
    Sean Paul, Software Engineer, Google / Chromium OS

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