On Thu, Nov 17, 2022 at 09:28:49AM -0800, Nick Desaulniers wrote:
> On Thu, Nov 10, 2022 at 02:47:52PM +0100, José Expósito wrote:
> > Commit 6bed2ea3cb38 ("drm/vc4: hdmi: Reset link on hotplug") introduced
> > the vc4_hdmi_reset_link() function. This function dereferences the
> > "connector" pointer before checking whether it is NULL or not.
> >
> > Rework variable assignment to avoid this issue.
> >
> > Fixes: 6bed2ea3cb38 ("drm/vc4: hdmi: Reset link on hotplug")
> > Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/vc4/vc4_hdmi.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > index a49f88e5d2b9..6b223a5fcf6f 100644
> > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > @@ -318,8 +318,8 @@ static int reset_pipe(struct drm_crtc *crtc,
> > static int vc4_hdmi_reset_link(struct drm_connector *connector,
> > struct drm_modeset_acquire_ctx *ctx)
> > {
> > - struct drm_device *drm = connector->dev;
> > - struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
> > + struct drm_device *drm;
> > + struct vc4_hdmi *vc4_hdmi;
>
> Hi, I think this change, or another in this area recently, is causing
> the following warning. PTAL
>
> drivers/gpu/drm/vc4/vc4_hdmi.c:351:14: warning: variable 'vc4_hdmi' is uninitialized when used here [-Wuninitialized]
> mutex_lock(&vc4_hdmi->mutex);
> ^~~~~~~~
> drivers/gpu/drm/vc4/vc4_hdmi.c:322:27: note: initialize the variable 'vc4_hdmi' to silence this warning
> struct vc4_hdmi *vc4_hdmi;
> ^
> = NULL
Guess we just crossed paths but this is just a problem with -next due to
a bad conflict resolution on Stephen's part:
https://lore.kernel.org/Y3ZvffZiR+SgtY6h@dev-arch.thelio-3990X/
> > struct drm_connector_state *conn_state;
> > struct drm_crtc_state *crtc_state;
> > struct drm_crtc *crtc;
> > @@ -330,6 +330,7 @@ static int vc4_hdmi_reset_link(struct drm_connector *connector,
> > if (!connector)
> > return 0;
> >
> > + drm = connector->dev;
> > ret = drm_modeset_lock(&drm->mode_config.connection_mutex, ctx);
> > if (ret)
> > return ret;
> > @@ -347,6 +348,7 @@ static int vc4_hdmi_reset_link(struct drm_connector *connector,
> > if (!crtc_state->active)
> > return 0;
> >
> > + vc4_hdmi = connector_to_vc4_hdmi(connector);
This version of the patch is fine, as there is no mutex_lock() call
here.
> > if (!vc4_hdmi_supports_scrambling(vc4_hdmi))
> > return 0;
> >
> > --
> > 2.25.1
> >
> >
>
Cheers,
Nathan
