Re: [PATCH v4 02/12] drm/client: Restrict the plane_state scope
On Fri, 14 Jun 2019, Maxime Ripard wrote:
> Hi Jani,
>
> On Fri, Jun 14, 2019 at 03:28:59PM +0300, Jani Nikula wrote:
>> On Fri, 14 Jun 2019, Maxime Ripard 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
>> > ---
>> > 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
Indeed, sorry for the noise.
BR,
Jani.
--
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Re: [PATCH v4 02/12] drm/client: Restrict the plane_state scope
Den 14.06.2019 14.13, skrev Maxime Ripard: > 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. > > Signed-off-by: Maxime Ripard > --- Reviewed-by: Noralf Trønnes ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: [PATCH v4 02/12] drm/client: Restrict the plane_state scope
Hi Jani,
On Fri, Jun 14, 2019 at 03:28:59PM +0300, Jani Nikula wrote:
> On Fri, 14 Jun 2019, Maxime Ripard 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
> > ---
> > 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
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Embedded Linux and Kernel engineering
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Re: [PATCH v4 02/12] drm/client: Restrict the plane_state scope
On Fri, 14 Jun 2019, Maxime Ripard 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.
BR,
Jani.
>
> Signed-off-by: Maxime Ripard
> ---
> 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;
> +
> /* Cannot fail as we've already gotten the plane state
> above */
> plane_state = drm_atomic_get_new_plane_state(state,
> primary);
> plane_state->rotation = rotation;
--
Jani Nikula, Intel Open Source Graphics Center
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