FAILED: patch "[PATCH] drm/atomic_helper: Disallow new modesets on unregistered" failed to apply to 4.20-stable tree

FAILED: patch "[PATCH] drm/atomic_helper: Disallow new modesets on unregistered" failed to apply to 4.20-stable tree

[gregkh]

The patch below does not apply to the 4.20-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4d80273976bf880c4bed9359b8f2d45663140c86 Mon Sep 17 00:00:00 2001
From: Lyude Paul <lyude@redhat.com>
Date: Mon, 8 Oct 2018 19:24:30 -0400
Subject: [PATCH] drm/atomic_helper: Disallow new modesets on unregistered
 connectors

With the exception of modesets which would switch the DPMS state of a
connector from on to off, we want to make sure that we disallow all
modesets which would result in enabling a new monitor or a new mode
configuration on a monitor if the connector for the display in question
is no longer registered. This allows us to stop userspace from trying to
enable new displays on connectors for an MST topology that were just
removed from the system, without preventing userspace from disabling
DPMS on those connectors.

Changes since v5:
- Fix typo in comment, nothing else

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20181008232437.5571-2-lyude@redhat.com

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 3cf1aa132778..c1a35078b2b9 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -308,6 +308,26 @@ update_connector_routing(struct drm_atomic_state *state,
 		return 0;
 	}
 
+	crtc_state = drm_atomic_get_new_crtc_state(state,
+						   new_connector_state->crtc);
+	/*
+	 * For compatibility with legacy users, we want to make sure that
+	 * we allow DPMS On->Off modesets on unregistered connectors. Modesets
+	 * which would result in anything else must be considered invalid, to
+	 * avoid turning on new displays on dead connectors.
+	 *
+	 * Since the connector can be unregistered at any point during an
+	 * atomic check or commit, this is racy. But that's OK: all we care
+	 * about is ensuring that userspace can't do anything but shut off the
+	 * display on a connector that was destroyed after its been notified,
+	 * not before.
+	 */
+	if (!READ_ONCE(connector->registered) && crtc_state->active) {
+		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] is not registered\n",
+				 connector->base.id, connector->name);
+		return -EINVAL;
+	}
+
 	funcs = connector->helper_private;
 
 	if (funcs->atomic_best_encoder)
@@ -352,7 +372,6 @@ update_connector_routing(struct drm_atomic_state *state,
 
 	set_best_encoder(state, new_connector_state, new_encoder);
 
-	crtc_state = drm_atomic_get_new_crtc_state(state, new_connector_state->crtc);
 	crtc_state->connectors_changed = true;
 
 	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d:%s]\n",

Re: FAILED: patch "[PATCH] drm/atomic_helper: Disallow new modesets on unregistered" failed to apply to 4.20-stable tree

[Lyude Paul]

This patch got obsoleted and cc'd by accident, feel free to ignore

On Fri, 2019-01-11 at 14:01 +0100, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 4.20-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 4d80273976bf880c4bed9359b8f2d45663140c86 Mon Sep 17 00:00:00 2001
> From: Lyude Paul <lyude@redhat.com>
> Date: Mon, 8 Oct 2018 19:24:30 -0400
> Subject: [PATCH] drm/atomic_helper: Disallow new modesets on unregistered
>  connectors
> 
> With the exception of modesets which would switch the DPMS state of a
> connector from on to off, we want to make sure that we disallow all
> modesets which would result in enabling a new monitor or a new mode
> configuration on a monitor if the connector for the display in question
> is no longer registered. This allows us to stop userspace from trying to
> enable new displays on connectors for an MST topology that were just
> removed from the system, without preventing userspace from disabling
> DPMS on those connectors.
> 
> Changes since v5:
> - Fix typo in comment, nothing else
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: stable@vger.kernel.org
> Link: 
> https://patchwork.freedesktop.org/patch/msgid/20181008232437.5571-2-lyude@redhat.com
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c
> index 3cf1aa132778..c1a35078b2b9 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -308,6 +308,26 @@ update_connector_routing(struct drm_atomic_state
> *state,
>  		return 0;
>  	}
>  
> +	crtc_state = drm_atomic_get_new_crtc_state(state,
> +						   new_connector_state->crtc);
> +	/*
> +	 * For compatibility with legacy users, we want to make sure that
> +	 * we allow DPMS On->Off modesets on unregistered connectors. Modesets
> +	 * which would result in anything else must be considered invalid, to
> +	 * avoid turning on new displays on dead connectors.
> +	 *
> +	 * Since the connector can be unregistered at any point during an
> +	 * atomic check or commit, this is racy. But that's OK: all we care
> +	 * about is ensuring that userspace can't do anything but shut off the
> +	 * display on a connector that was destroyed after its been notified,
> +	 * not before.
> +	 */
> +	if (!READ_ONCE(connector->registered) && crtc_state->active) {
> +		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] is not registered\n",
> +				 connector->base.id, connector->name);
> +		return -EINVAL;
> +	}
> +
>  	funcs = connector->helper_private;
>  
>  	if (funcs->atomic_best_encoder)
> @@ -352,7 +372,6 @@ update_connector_routing(struct drm_atomic_state *state,
>  
>  	set_best_encoder(state, new_connector_state, new_encoder);
>  
> -	crtc_state = drm_atomic_get_new_crtc_state(state, new_connector_state-
> >crtc);
>  	crtc_state->connectors_changed = true;
>  
>  	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on
> [CRTC:%d:%s]\n",
> 
-- 
Cheers,
	Lyude Paul