From 4e804ef40f46136d4fe84603a8236adc172260f8 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Tue, 19 Dec 2017 18:14:47 -0500
Subject: [PATCH 01/11] add backend destroy event

---
 backend/backend.c     | 2 ++
 include/wlr/backend.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/backend/backend.c b/backend/backend.c
index f93dde38..58181947 100644
--- a/backend/backend.c
+++ b/backend/backend.c
@@ -18,6 +18,7 @@ void wlr_backend_init(struct wlr_backend *backend,
 		const struct wlr_backend_impl *impl) {
 	assert(backend);
 	backend->impl = impl;
+	wl_signal_init(&backend->events.destroy);
 	wl_signal_init(&backend->events.input_add);
 	wl_signal_init(&backend->events.input_remove);
 	wl_signal_init(&backend->events.output_add);
@@ -32,6 +33,7 @@ bool wlr_backend_start(struct wlr_backend *backend) {
 }
 
 void wlr_backend_destroy(struct wlr_backend *backend) {
+	wl_signal_emit(&backend->events.destroy, backend);
 	if (backend->impl && backend->impl->destroy) {
 		backend->impl->destroy(backend);
 	} else {
diff --git a/include/wlr/backend.h b/include/wlr/backend.h
index 2c8fd982..4632dcbf 100644
--- a/include/wlr/backend.h
+++ b/include/wlr/backend.h
@@ -11,6 +11,7 @@ struct wlr_backend {
 	const struct wlr_backend_impl *impl;
 
 	struct {
+		struct wl_signal destroy;
 		struct wl_signal input_add;
 		struct wl_signal input_remove;
 		struct wl_signal output_add;

From a937016e38efe3d7ad71540755833242059e6902 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Tue, 19 Dec 2017 18:25:46 -0500
Subject: [PATCH 02/11] remove session from multibackend

---
 backend/backend.c           |  2 +-
 backend/drm/backend.c       |  5 +++++
 backend/multi/backend.c     | 22 +++++++++-------------
 include/backend/drm/drm.h   |  2 ++
 include/backend/multi.h     |  1 -
 include/wlr/backend/multi.h |  4 ++--
 6 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/backend/backend.c b/backend/backend.c
index 58181947..7dfd6676 100644
--- a/backend/backend.c
+++ b/backend/backend.c
@@ -93,7 +93,7 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		return NULL;
 	}
 
-	backend = wlr_multi_backend_create(display, session);
+	backend = wlr_multi_backend_create(display);
 	if (!backend) {
 		goto error_session;
 	}
diff --git a/backend/drm/backend.c b/backend/drm/backend.c
index 6be5e5d5..112b2b61 100644
--- a/backend/drm/backend.c
+++ b/backend/drm/backend.c
@@ -174,3 +174,8 @@ error_fd:
 	free(drm);
 	return NULL;
 }
+
+struct wlr_session *wlr_drm_backend_get_session(struct wlr_backend *backend) {
+	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)backend;
+	return drm->session;
+}
diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index 3815a0bc..df7c8c6d 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -5,6 +5,7 @@
 #include <wlr/backend/session.h>
 #include <wlr/util/log.h>
 #include "backend/multi.h"
+#include "backend/drm/drm.h"
 
 struct subbackend_state {
 	struct wlr_backend *backend;
@@ -57,14 +58,7 @@ struct wlr_backend_impl backend_impl = {
 	.get_egl = multi_backend_get_egl,
 };
 
-static void handle_display_destroy(struct wl_listener *listener, void *data) {
-	struct wlr_multi_backend *backend =
-		wl_container_of(listener, backend, display_destroy);
-	multi_backend_destroy(&backend->backend);
-}
-
-struct wlr_backend *wlr_multi_backend_create(struct wl_display *display,
-		struct wlr_session *session) {
+struct wlr_backend *wlr_multi_backend_create(struct wl_display *display) {
 	struct wlr_multi_backend *backend =
 		calloc(1, sizeof(struct wlr_multi_backend));
 	if (!backend) {
@@ -72,13 +66,9 @@ struct wlr_backend *wlr_multi_backend_create(struct wl_display *display,
 		return NULL;
 	}
 
-	backend->session = session;
 	wl_list_init(&backend->backends);
 	wlr_backend_init(&backend->backend, &backend_impl);
 
-	session->display_destroy.notify = handle_display_destroy;
-	wl_display_add_destroy_listener(display, &session->display_destroy);
-
 	return &backend->backend;
 }
 
@@ -140,5 +130,11 @@ struct wlr_session *wlr_multi_get_session(struct wlr_backend *_backend) {
 	assert(wlr_backend_is_multi(_backend));
 
 	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)_backend;
-	return backend->session;
+	struct subbackend_state *sub;
+	wl_list_for_each(sub, &backend->backends, link) {
+		if (wlr_backend_is_drm(sub->backend)) {
+			return wlr_drm_backend_get_session(sub->backend);
+		}
+	}
+	return NULL;
 }
diff --git a/include/backend/drm/drm.h b/include/backend/drm/drm.h
index 278c387c..72671f45 100644
--- a/include/backend/drm/drm.h
+++ b/include/backend/drm/drm.h
@@ -143,4 +143,6 @@ int wlr_drm_event(int fd, uint32_t mask, void *data);
 
 void wlr_drm_connector_start_renderer(struct wlr_drm_connector *conn);
 
+struct wlr_session *wlr_drm_backend_get_session(struct wlr_backend *backend);
+
 #endif
diff --git a/include/backend/multi.h b/include/backend/multi.h
index 2798048d..f0e50fc0 100644
--- a/include/backend/multi.h
+++ b/include/backend/multi.h
@@ -9,7 +9,6 @@
 struct wlr_multi_backend {
 	struct wlr_backend backend;
 
-	struct wlr_session *session;
 	struct wl_list backends;
 
 	struct wl_listener display_destroy;
diff --git a/include/wlr/backend/multi.h b/include/wlr/backend/multi.h
index e56b07b1..fc53f369 100644
--- a/include/wlr/backend/multi.h
+++ b/include/wlr/backend/multi.h
@@ -4,8 +4,8 @@
 #include <wlr/backend.h>
 #include <wlr/backend/session.h>
 
-struct wlr_backend *wlr_multi_backend_create(struct wl_display *display,
-	struct wlr_session *session);
+struct wlr_backend *wlr_multi_backend_create(struct wl_display *display);
+
 void wlr_multi_backend_add(struct wlr_backend *multi,
 	struct wlr_backend *backend);
 

From 6c75a184e7f05305fce8f693052a40047b07fc2f Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Tue, 19 Dec 2017 18:33:26 -0500
Subject: [PATCH 03/11] subbackend state destroy

---
 backend/multi/backend.c | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index df7c8c6d..8659d8ec 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -14,6 +14,7 @@ struct subbackend_state {
 	struct wl_listener input_remove;
 	struct wl_listener output_add;
 	struct wl_listener output_remove;
+	struct wl_listener backend_destroy;
 	struct wl_list link;
 };
 
@@ -29,13 +30,23 @@ static bool multi_backend_start(struct wlr_backend *wlr_backend) {
 	return true;
 }
 
+static void subbackend_state_destroy(struct subbackend_state *sub) {
+	wl_list_remove(&sub->input_add.link);
+	wl_list_remove(&sub->input_remove.link);
+	wl_list_remove(&sub->output_add.link);
+	wl_list_remove(&sub->output_remove.link);
+	wl_list_remove(&sub->backend_destroy.link);
+	wl_list_remove(&sub->link);
+	free(sub);
+}
+
 static void multi_backend_destroy(struct wlr_backend *wlr_backend) {
 	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)wlr_backend;
 	wl_list_remove(&backend->display_destroy.link);
 	struct subbackend_state *sub, *next;
 	wl_list_for_each_safe(sub, next, &backend->backends, link) {
+		// XXX do we really want to take ownership over added backends?
 		wlr_backend_destroy(sub->backend);
-		free(sub);
 	}
 	free(backend);
 }
@@ -100,6 +111,13 @@ static void output_remove_reemit(struct wl_listener *listener, void *data) {
 	wl_signal_emit(&state->container->events.output_remove, data);
 }
 
+static void handle_subbackend_destroy(struct wl_listener *listener,
+		void *data) {
+	struct subbackend_state *state = wl_container_of(listener,
+			state, backend_destroy);
+	subbackend_state_destroy(state);
+}
+
 void wlr_multi_backend_add(struct wlr_backend *_multi,
 		struct wlr_backend *backend) {
 	assert(wlr_backend_is_multi(_multi));
@@ -115,15 +133,20 @@ void wlr_multi_backend_add(struct wlr_backend *_multi,
 	sub->backend = backend;
 	sub->container = &multi->backend;
 
-	sub->input_add.notify = input_add_reemit;
-	sub->input_remove.notify = input_remove_reemit;
-	sub->output_add.notify = output_add_reemit;
-	sub->output_remove.notify = output_remove_reemit;
+	wl_signal_add(&backend->events.destroy, &sub->backend_destroy);
+	sub->backend_destroy.notify = handle_subbackend_destroy;
 
 	wl_signal_add(&backend->events.input_add, &sub->input_add);
+	sub->input_add.notify = input_add_reemit;
+
 	wl_signal_add(&backend->events.input_remove, &sub->input_remove);
+	sub->input_remove.notify = input_remove_reemit;
+
 	wl_signal_add(&backend->events.output_add, &sub->output_add);
+	sub->output_add.notify = output_add_reemit;
+
 	wl_signal_add(&backend->events.output_remove, &sub->output_remove);
+	sub->output_remove.notify = output_remove_reemit;
 }
 
 struct wlr_session *wlr_multi_get_session(struct wlr_backend *_backend) {

From 58e69c9ce177f3de4790bddd161e9d74dd2e512c Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Tue, 19 Dec 2017 18:49:00 -0500
Subject: [PATCH 04/11] multibackend remove subbackend

---
 backend/multi/backend.c     | 31 ++++++++++++++++++++++++++++++-
 include/wlr/backend/multi.h |  3 +++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index 8659d8ec..e6be4a20 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -118,11 +118,27 @@ static void handle_subbackend_destroy(struct wl_listener *listener,
 	subbackend_state_destroy(state);
 }
 
+static struct subbackend_state *multi_backend_get_subbackend(struct wlr_multi_backend *multi,
+		struct wlr_backend *backend) {
+	struct subbackend_state *sub = NULL;
+	wl_list_for_each(sub, &multi->backends, link) {
+		if (sub->backend == backend) {
+			return sub;
+		}
+	}
+	return NULL;
+}
+
 void wlr_multi_backend_add(struct wlr_backend *_multi,
 		struct wlr_backend *backend) {
 	assert(wlr_backend_is_multi(_multi));
-
 	struct wlr_multi_backend *multi = (struct wlr_multi_backend *)_multi;
+
+	if (multi_backend_get_subbackend(multi, backend)) {
+		// already added
+		return;
+	}
+
 	struct subbackend_state *sub;
 	if (!(sub = calloc(1, sizeof(struct subbackend_state)))) {
 		wlr_log(L_ERROR, "Could not add backend: allocation failed");
@@ -149,6 +165,19 @@ void wlr_multi_backend_add(struct wlr_backend *_multi,
 	sub->output_remove.notify = output_remove_reemit;
 }
 
+void wlr_multi_backend_remove(struct wlr_backend *_multi,
+		struct wlr_backend *backend) {
+	assert(wlr_backend_is_multi(_multi));
+	struct wlr_multi_backend *multi = (struct wlr_multi_backend *)_multi;
+
+	struct subbackend_state *sub =
+		multi_backend_get_subbackend(multi, backend);
+
+	if (sub) {
+		subbackend_state_destroy(sub);
+	}
+}
+
 struct wlr_session *wlr_multi_get_session(struct wlr_backend *_backend) {
 	assert(wlr_backend_is_multi(_backend));
 
diff --git a/include/wlr/backend/multi.h b/include/wlr/backend/multi.h
index fc53f369..35f7c165 100644
--- a/include/wlr/backend/multi.h
+++ b/include/wlr/backend/multi.h
@@ -9,6 +9,9 @@ struct wlr_backend *wlr_multi_backend_create(struct wl_display *display);
 void wlr_multi_backend_add(struct wlr_backend *multi,
 	struct wlr_backend *backend);
 
+void wlr_multi_backend_remove(struct wlr_backend *multi,
+	struct wlr_backend *backend);
+
 bool wlr_backend_is_multi(struct wlr_backend *backend);
 
 struct wlr_session *wlr_multi_get_session(struct wlr_backend *base);

From ca6a0ef1bbbd611c9ebf0ace08b8fc6af3883d09 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Tue, 19 Dec 2017 19:07:33 -0500
Subject: [PATCH 05/11] always return multibakend from autocreate

---
 backend/backend.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/backend/backend.c b/backend/backend.c
index 7dfd6676..2adc3171 100644
--- a/backend/backend.c
+++ b/backend/backend.c
@@ -72,30 +72,31 @@ static struct wlr_backend *attempt_wl_backend(struct wl_display *display) {
 }
 
 struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
-	struct wlr_backend *backend;
+	struct wlr_backend *backend = wlr_multi_backend_create(display);
+	if (!backend) {
+		wlr_log(L_ERROR, "could not allocate multibackend");
+		return NULL;
+	}
+
 	if (getenv("WAYLAND_DISPLAY") || getenv("_WAYLAND_DISPLAY")) {
-		backend = attempt_wl_backend(display);
-		if (backend) {
-			return backend;
+		struct wlr_backend *wl_backend = attempt_wl_backend(display);
+		if (wl_backend) {
+			wlr_multi_backend_add(backend, wl_backend);
 		}
 	}
 
 	const char *x11_display = getenv("DISPLAY");
 	if (x11_display) {
-		return wlr_x11_backend_create(display, x11_display);
+		struct wlr_backend *x11_backend =
+			wlr_x11_backend_create(display, x11_display);
+		wlr_multi_backend_add(backend, x11_backend);
 	}
 
 	// Attempt DRM+libinput
-
 	struct wlr_session *session = wlr_session_create(display);
 	if (!session) {
 		wlr_log(L_ERROR, "Failed to start a DRM session");
-		return NULL;
-	}
-
-	backend = wlr_multi_backend_create(display);
-	if (!backend) {
-		goto error_session;
+		return backend;
 	}
 
 	struct wlr_backend *libinput = wlr_libinput_backend_create(display, session);
@@ -134,9 +135,8 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 
 error_multi:
 	wlr_backend_destroy(backend);
-error_session:
 	wlr_session_destroy(session);
-	return NULL;
+	return backend;
 }
 
 uint32_t usec_to_msec(uint64_t usec) {

From ee39dff1e7de4a234f2ff39c1ce2df6bc84abb04 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Wed, 20 Dec 2017 05:51:23 -0500
Subject: [PATCH 06/11] rootston: handle backend creation failed

---
 backend/multi/backend.c     | 7 ++++++-
 include/backend/multi.h     | 2 --
 include/wlr/backend/multi.h | 2 ++
 rootston/main.c             | 7 +++++++
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index e6be4a20..c000342b 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -42,7 +42,6 @@ static void subbackend_state_destroy(struct subbackend_state *sub) {
 
 static void multi_backend_destroy(struct wlr_backend *wlr_backend) {
 	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)wlr_backend;
-	wl_list_remove(&backend->display_destroy.link);
 	struct subbackend_state *sub, *next;
 	wl_list_for_each_safe(sub, next, &backend->backends, link) {
 		// XXX do we really want to take ownership over added backends?
@@ -190,3 +189,9 @@ struct wlr_session *wlr_multi_get_session(struct wlr_backend *_backend) {
 	}
 	return NULL;
 }
+
+bool wlr_multi_is_empty(struct wlr_backend *_backend) {
+	assert(wlr_backend_is_multi(_backend));
+	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)_backend;
+	return wl_list_length(&backend->backends) < 1;
+}
diff --git a/include/backend/multi.h b/include/backend/multi.h
index f0e50fc0..e283139c 100644
--- a/include/backend/multi.h
+++ b/include/backend/multi.h
@@ -10,8 +10,6 @@ struct wlr_multi_backend {
 	struct wlr_backend backend;
 
 	struct wl_list backends;
-
-	struct wl_listener display_destroy;
 };
 
 #endif
diff --git a/include/wlr/backend/multi.h b/include/wlr/backend/multi.h
index 35f7c165..d9914efc 100644
--- a/include/wlr/backend/multi.h
+++ b/include/wlr/backend/multi.h
@@ -16,4 +16,6 @@ bool wlr_backend_is_multi(struct wlr_backend *backend);
 
 struct wlr_session *wlr_multi_get_session(struct wlr_backend *base);
 
+bool wlr_multi_is_empty(struct wlr_backend *backend);
+
 #endif
diff --git a/rootston/main.c b/rootston/main.c
index aa20dbba..2f913272 100644
--- a/rootston/main.c
+++ b/rootston/main.c
@@ -5,6 +5,7 @@
 #include <wayland-server.h>
 #include <wlr/backend.h>
 #include <wlr/backend/headless.h>
+#include <wlr/backend/multi.h>
 #include <wlr/render.h>
 #include <wlr/render/gles2.h>
 #include <wlr/util/log.h>
@@ -32,6 +33,12 @@ int main(int argc, char **argv) {
 
 	assert(server.backend = wlr_backend_autocreate(server.wl_display));
 
+	if (wlr_multi_is_empty(server.backend)) {
+		wlr_log(L_ERROR, "could not start backend");
+		wlr_backend_destroy(server.backend);
+		return 1;
+	}
+
 	assert(server.renderer = wlr_gles2_renderer_create(server.backend));
 	server.data_device_manager =
 		wlr_data_device_manager_create(server.wl_display);

From 6c8fd6017e92441e8b1702958f34fd9d88e32928 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Wed, 20 Dec 2017 05:54:41 -0500
Subject: [PATCH 07/11] backend add and remove events

---
 backend/multi/backend.c | 6 ++++++
 include/backend/multi.h | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index c000342b..0dd3c54b 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -79,6 +79,9 @@ struct wlr_backend *wlr_multi_backend_create(struct wl_display *display) {
 	wl_list_init(&backend->backends);
 	wlr_backend_init(&backend->backend, &backend_impl);
 
+	wl_signal_init(&backend->events.backend_add);
+	wl_signal_init(&backend->events.backend_remove);
+
 	return &backend->backend;
 }
 
@@ -162,6 +165,8 @@ void wlr_multi_backend_add(struct wlr_backend *_multi,
 
 	wl_signal_add(&backend->events.output_remove, &sub->output_remove);
 	sub->output_remove.notify = output_remove_reemit;
+
+	wl_signal_emit(&multi->events.backend_add, backend);
 }
 
 void wlr_multi_backend_remove(struct wlr_backend *_multi,
@@ -173,6 +178,7 @@ void wlr_multi_backend_remove(struct wlr_backend *_multi,
 		multi_backend_get_subbackend(multi, backend);
 
 	if (sub) {
+		wl_signal_emit(&multi->events.backend_remove, backend);
 		subbackend_state_destroy(sub);
 	}
 }
diff --git a/include/backend/multi.h b/include/backend/multi.h
index e283139c..947464e1 100644
--- a/include/backend/multi.h
+++ b/include/backend/multi.h
@@ -10,6 +10,11 @@ struct wlr_multi_backend {
 	struct wlr_backend backend;
 
 	struct wl_list backends;
+
+	struct {
+		struct wl_signal backend_add;
+		struct wl_signal backend_remove;
+	} events;
 };
 
 #endif

From d1dce19253d0b4d30d99d2074a05fe7970391a61 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Thu, 21 Dec 2017 08:13:36 -0500
Subject: [PATCH 08/11] handle display destroy

---
 backend/multi/backend.c | 10 +++++++++-
 include/backend/multi.h |  2 ++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index 0dd3c54b..07e84c01 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -44,7 +44,6 @@ static void multi_backend_destroy(struct wlr_backend *wlr_backend) {
 	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)wlr_backend;
 	struct subbackend_state *sub, *next;
 	wl_list_for_each_safe(sub, next, &backend->backends, link) {
-		// XXX do we really want to take ownership over added backends?
 		wlr_backend_destroy(sub->backend);
 	}
 	free(backend);
@@ -68,6 +67,12 @@ struct wlr_backend_impl backend_impl = {
 	.get_egl = multi_backend_get_egl,
 };
 
+static void handle_display_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_multi_backend *backend =
+		wl_container_of(listener, backend, display_destroy);
+	multi_backend_destroy((struct wlr_backend*)backend);
+}
+
 struct wlr_backend *wlr_multi_backend_create(struct wl_display *display) {
 	struct wlr_multi_backend *backend =
 		calloc(1, sizeof(struct wlr_multi_backend));
@@ -82,6 +87,9 @@ struct wlr_backend *wlr_multi_backend_create(struct wl_display *display) {
 	wl_signal_init(&backend->events.backend_add);
 	wl_signal_init(&backend->events.backend_remove);
 
+	backend->display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(display, &backend->display_destroy);
+
 	return &backend->backend;
 }
 
diff --git a/include/backend/multi.h b/include/backend/multi.h
index 947464e1..3363c608 100644
--- a/include/backend/multi.h
+++ b/include/backend/multi.h
@@ -11,6 +11,8 @@ struct wlr_multi_backend {
 
 	struct wl_list backends;
 
+	struct wl_listener display_destroy;
+
 	struct {
 		struct wl_signal backend_add;
 		struct wl_signal backend_remove;

From b4159c52d5ee8bbcfdee291b19b503f9af7b24cd Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Thu, 21 Dec 2017 08:33:34 -0500
Subject: [PATCH 09/11] autocreate backend returns null instead of empty

---
 backend/backend.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/backend/backend.c b/backend/backend.c
index 2adc3171..359ee0e5 100644
--- a/backend/backend.c
+++ b/backend/backend.c
@@ -96,16 +96,14 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 	struct wlr_session *session = wlr_session_create(display);
 	if (!session) {
 		wlr_log(L_ERROR, "Failed to start a DRM session");
-		return backend;
+		goto out;
 	}
 
 	struct wlr_backend *libinput = wlr_libinput_backend_create(display, session);
-	if (!libinput) {
-		goto error_multi;
+	if (libinput) {
+		wlr_multi_backend_add(backend, libinput);
 	}
 
-	wlr_multi_backend_add(backend, libinput);
-
 	int gpus[8];
 	size_t num_gpus = wlr_session_find_gpus(session, 8, gpus);
 	struct wlr_backend *primary_drm = NULL;
@@ -128,14 +126,14 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 
 	if (!primary_drm) {
 		wlr_log(L_ERROR, "Failed to open any DRM device");
-		goto error_multi;
 	}
 
-	return backend;
+out:
+	if (wlr_multi_is_empty(backend)) {
+		wlr_backend_destroy(backend);
+		return NULL;
+	}
 
-error_multi:
-	wlr_backend_destroy(backend);
-	wlr_session_destroy(session);
 	return backend;
 }
 

From 9871cde60433699468e2bd30b60382904173ba55 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Thu, 21 Dec 2017 18:27:38 -0500
Subject: [PATCH 10/11] rootston: server backend check

---
 rootston/main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rootston/main.c b/rootston/main.c
index 2f913272..161824d6 100644
--- a/rootston/main.c
+++ b/rootston/main.c
@@ -31,9 +31,9 @@ int main(int argc, char **argv) {
 	assert(server.wl_display = wl_display_create());
 	assert(server.wl_event_loop = wl_display_get_event_loop(server.wl_display));
 
-	assert(server.backend = wlr_backend_autocreate(server.wl_display));
+	server.backend = wlr_backend_autocreate(server.wl_display);
 
-	if (wlr_multi_is_empty(server.backend)) {
+	if (server.backend == NULL) {
 		wlr_log(L_ERROR, "could not start backend");
 		wlr_backend_destroy(server.backend);
 		return 1;

From 4cec7f54e24a58fd9756395ce64a5bd73f412c9e Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Thu, 21 Dec 2017 18:38:58 -0500
Subject: [PATCH 11/11] only add first backend to multi autocreate

---
 backend/backend.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/backend/backend.c b/backend/backend.c
index 359ee0e5..6b32bc6a 100644
--- a/backend/backend.c
+++ b/backend/backend.c
@@ -33,6 +33,10 @@ bool wlr_backend_start(struct wlr_backend *backend) {
 }
 
 void wlr_backend_destroy(struct wlr_backend *backend) {
+	if (!backend) {
+		return;
+	}
+
 	wl_signal_emit(&backend->events.destroy, backend);
 	if (backend->impl && backend->impl->destroy) {
 		backend->impl->destroy(backend);
@@ -82,6 +86,7 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		struct wlr_backend *wl_backend = attempt_wl_backend(display);
 		if (wl_backend) {
 			wlr_multi_backend_add(backend, wl_backend);
+			return backend;
 		}
 	}
 
@@ -90,18 +95,25 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		struct wlr_backend *x11_backend =
 			wlr_x11_backend_create(display, x11_display);
 		wlr_multi_backend_add(backend, x11_backend);
+		return backend;
 	}
 
 	// Attempt DRM+libinput
 	struct wlr_session *session = wlr_session_create(display);
 	if (!session) {
 		wlr_log(L_ERROR, "Failed to start a DRM session");
-		goto out;
+		wlr_backend_destroy(backend);
+		return NULL;
 	}
 
 	struct wlr_backend *libinput = wlr_libinput_backend_create(display, session);
 	if (libinput) {
 		wlr_multi_backend_add(backend, libinput);
+	} else {
+		wlr_log(L_ERROR, "Failed to start libinput backend");
+		wlr_backend_destroy(backend);
+		wlr_session_destroy(session);
+		return NULL;
 	}
 
 	int gpus[8];
@@ -126,10 +138,8 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 
 	if (!primary_drm) {
 		wlr_log(L_ERROR, "Failed to open any DRM device");
-	}
-
-out:
-	if (wlr_multi_is_empty(backend)) {
+		wlr_backend_destroy(libinput);
+		wlr_session_destroy(session);
 		wlr_backend_destroy(backend);
 		return NULL;
 	}