[PATCH v4 02/12] drm/client: Restrict the plane_state scope
Maxime Ripard
maxime.ripard at bootlin.com
Fri Jun 14 14:12:11 UTC 2019
Hi Jani,
On Fri, Jun 14, 2019 at 03:28:59PM +0300, Jani Nikula wrote:
> On Fri, 14 Jun 2019, Maxime Ripard <maxime.ripard at bootlin.com> wrote:
> > The drm_client_modeset_commit_atomic function uses two times the
> > plane_state variable in inner blocks of code, but the variable has a scope
> > global to this function.
> >
> > This will lead to inadvertent devs to reuse the variable in the second
> > block with the value left by the first, without any warning from the
> > compiler since value would have been initialized.
> >
> > Fix this by moving the variable declaration to the proper scope.
>
> This is an improvement, but I'd consider renaming also to not shadow
> variables.
>
> > Signed-off-by: Maxime Ripard <maxime.ripard at bootlin.com>
> > ---
> > drivers/gpu/drm/drm_client_modeset.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
> > index 006bf7390e7d..8264c3a732b0 100644
> > --- a/drivers/gpu/drm/drm_client_modeset.c
> > +++ b/drivers/gpu/drm/drm_client_modeset.c
> > @@ -861,7 +861,6 @@ EXPORT_SYMBOL(drm_client_panel_rotation);
> > static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool active)
> > {
> > struct drm_device *dev = client->dev;
> > - struct drm_plane_state *plane_state;
> > struct drm_plane *plane;
> > struct drm_atomic_state *state;
> > struct drm_modeset_acquire_ctx ctx;
> > @@ -879,6 +878,8 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
> > state->acquire_ctx = &ctx;
> > retry:
> > drm_for_each_plane(plane, dev) {
> > + struct drm_plane_state *plane_state;
> > +
> > plane_state = drm_atomic_get_plane_state(state, plane);
> > if (IS_ERR(plane_state)) {
> > ret = PTR_ERR(plane_state);
> > @@ -901,6 +902,8 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
> > unsigned int rotation;
> >
> > if (drm_client_panel_rotation(mode_set, &rotation)) {
> > + struct drm_plane_state *plane_state;
> > +
That's not super clear from that patch, but this variable will not
shadow the first one.
The code layout is pretty much this one:
loop () {
struct drm_plane_state *plane_state;
[...]
}
loop () {
loop () {
struct drm_plane_state *plane_state;
[...]
}
}
so the shadowing doesn't exist
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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