render: use dev_t when creating renderer

We don't actually need to open a DRM node here. We just need a way
to reference a DRM node. A dev_t is better suited for this.

include/render/egl.h

@@ -53,11 +53,11 @@ struct wlr_egl_context {
 };
 
 /**
- * Initializes an EGL context for the given DRM FD.
+ * Initializes an EGL context for the given DRM device ID.
  *
  * Will attempt to load all possibly required API functions.
  */
-struct wlr_egl *wlr_egl_create_with_drm_fd(int drm_fd);
+struct wlr_egl *wlr_egl_create_with_drm_dev_id(dev_t dev_id);
 
 /**
  * Frees all related EGL resources, makes the context not-current and

include/render/vulkan.h

@@ -61,9 +61,9 @@ struct wlr_vk_device {
 	struct wlr_drm_format_set shm_texture_formats;
 };
 
-// Tries to find the VkPhysicalDevice for the given drm fd.
+// Tries to find the VkPhysicalDevice for the given DRM device ID.
 // Might find none and return VK_NULL_HANDLE.
-VkPhysicalDevice vulkan_find_drm_phdev(struct wlr_vk_instance *ini, int drm_fd);
+VkPhysicalDevice vulkan_find_drm_phdev(struct wlr_vk_instance *ini, dev_t dev_id);
 bool vulkan_get_phdev_drm_dev_id(VkPhysicalDevice phdev, dev_t *dev_id);
 
 // Creates a device for the given instance and physical device.

include/wlr/render/gles2.h

@@ -10,7 +10,6 @@
 #define WLR_RENDER_GLES2_H
 
 #include <GLES2/gl2.h>
-
 #include <wlr/render/wlr_renderer.h>
 
 struct wlr_egl;
@@ -28,7 +27,7 @@ struct wlr_egl;
  * render pass can't be used before the nested render pass is submitted.
  */
 
-struct wlr_renderer *wlr_gles2_renderer_create_with_drm_fd(int drm_fd);
+struct wlr_renderer *wlr_gles2_renderer_create_with_drm_dev_id(dev_t dev_id);
 struct wlr_renderer *wlr_gles2_renderer_create(struct wlr_egl *egl);
 
 struct wlr_egl *wlr_gles2_renderer_get_egl(struct wlr_renderer *renderer);

include/wlr/render/vulkan.h

@@ -18,7 +18,7 @@ struct wlr_vk_image_attribs {
 	VkFormat format;
 };
 
-struct wlr_renderer *wlr_vk_renderer_create_with_drm_fd(int drm_fd);
+struct wlr_renderer *wlr_vk_renderer_create_with_drm_dev_id(dev_t dev_id);
 
 VkInstance wlr_vk_renderer_get_instance(struct wlr_renderer *renderer);
 VkPhysicalDevice wlr_vk_renderer_get_physical_device(struct wlr_renderer *renderer);

render/egl.c

@@ -441,8 +441,7 @@ static bool egl_init(struct wlr_egl *egl, EGLenum platform,
 
 static bool device_has_name(const drmDevice *device, const char *name);
 
-static EGLDeviceEXT get_egl_device_from_drm_fd(struct wlr_egl *egl,
-		int drm_fd) {
+static EGLDeviceEXT get_egl_device_from_drm_dev_id(struct wlr_egl *egl, dev_t dev_id) {
 	if (egl->procs.eglQueryDevicesEXT == NULL) {
 		wlr_log(WLR_DEBUG, "EGL_EXT_device_enumeration not supported");
 		return EGL_NO_DEVICE_EXT;
@@ -469,9 +468,8 @@ static EGLDeviceEXT get_egl_device_from_drm_fd(struct wlr_egl *egl,
 	}
 
 	drmDevice *device = NULL;
-	int ret = drmGetDevice(drm_fd, &device);
-	if (ret < 0) {
-		wlr_log(WLR_ERROR, "Failed to get DRM device: %s", strerror(-ret));
+	if (drmGetDeviceFromDevId(dev_id, 0, &device) != 0) {
+		wlr_log(WLR_ERROR, "drmGetDeviceFromdev_id() failed");
 		return EGL_NO_DEVICE_EXT;
 	}
 
@@ -496,29 +494,32 @@ static EGLDeviceEXT get_egl_device_from_drm_fd(struct wlr_egl *egl,
 	return egl_device;
 }
 
-static int open_render_node(int drm_fd) {
-	char *render_name = drmGetRenderDeviceNameFromFd(drm_fd);
-	if (render_name == NULL) {
-		// This can happen on split render/display platforms, fallback to
-		// primary node
-		render_name = drmGetPrimaryDeviceNameFromFd(drm_fd);
-		if (render_name == NULL) {
-			wlr_log_errno(WLR_ERROR, "drmGetPrimaryDeviceNameFromFd failed");
-			return -1;
-		}
-		wlr_log(WLR_DEBUG, "DRM device '%s' has no render node, "
-			"falling back to primary node", render_name);
+static int open_render_node(dev_t dev_id) {
+	drmDevice *dev;
+	if (drmGetDeviceFromDevId(dev_id, 0, &dev) != 0) {
+		wlr_log(WLR_ERROR, "drmGetDeviceFromdev_id() failed");
+		return -1;
 	}
 
-	int render_fd = open(render_name, O_RDWR | O_CLOEXEC);
-	if (render_fd < 0) {
-		wlr_log_errno(WLR_ERROR, "Failed to open DRM node '%s'", render_name);
+	const char *node_name;
+	if (dev->available_nodes & (1 << DRM_NODE_RENDER)) {
+		node_name = dev->nodes[DRM_NODE_RENDER];
+	} else {
+		assert(dev->available_nodes & (1 << DRM_NODE_PRIMARY));
+		node_name = dev->nodes[DRM_NODE_PRIMARY];
+		wlr_log(WLR_DEBUG, "No DRM render node available, "
+			"falling back to primary node '%s'", node_name);
 	}
-	free(render_name);
+
+	int render_fd = open(node_name, O_RDWR | O_CLOEXEC);
+	if (render_fd < 0) {
+		wlr_log_errno(WLR_ERROR, "Failed to open DRM node '%s'", node_name);
+	}
+	drmFreeDevice(&dev);
 	return render_fd;
 }
 
-struct wlr_egl *wlr_egl_create_with_drm_fd(int drm_fd) {
+struct wlr_egl *wlr_egl_create_with_drm_dev_id(dev_t dev_id) {
 	struct wlr_egl *egl = egl_create();
 	if (egl == NULL) {
 		wlr_log(WLR_ERROR, "Failed to create EGL context");
@@ -530,7 +531,7 @@ struct wlr_egl *wlr_egl_create_with_drm_fd(int drm_fd) {
 		 * Search for the EGL device matching the DRM fd using the
 		 * EXT_device_enumeration extension.
 		 */
-		EGLDeviceEXT egl_device = get_egl_device_from_drm_fd(egl, drm_fd);
+		EGLDeviceEXT egl_device = get_egl_device_from_drm_dev_id(egl, dev_id);
 		if (egl_device != EGL_NO_DEVICE_EXT) {
 			if (egl_init(egl, EGL_PLATFORM_DEVICE_EXT, egl_device)) {
 				wlr_log(WLR_DEBUG, "Using EGL_PLATFORM_DEVICE_EXT");
@@ -544,7 +545,7 @@ struct wlr_egl *wlr_egl_create_with_drm_fd(int drm_fd) {
 	}
 
 	if (egl->exts.KHR_platform_gbm) {
-		int gbm_fd = open_render_node(drm_fd);
+		int gbm_fd = open_render_node(dev_id);
 		if (gbm_fd < 0) {
 			wlr_log(WLR_ERROR, "Failed to open DRM render node");
 			goto error;

render/gles2/renderer.c

@@ -476,8 +476,8 @@ static void load_gl_proc(void *proc_ptr, const char *name) {
 	*(void **)proc_ptr = proc;
 }
 
-struct wlr_renderer *wlr_gles2_renderer_create_with_drm_fd(int drm_fd) {
-	struct wlr_egl *egl = wlr_egl_create_with_drm_fd(drm_fd);
+struct wlr_renderer *wlr_gles2_renderer_create_with_drm_dev_id(dev_t dev_id) {
+	struct wlr_egl *egl = wlr_egl_create_with_drm_dev_id(dev_id);
 	if (egl == NULL) {
 		wlr_log(WLR_ERROR, "Could not initialize EGL");
 		return NULL;

render/vulkan/renderer.c

@@ -2193,7 +2193,7 @@ error:
 	return NULL;
 }
 
-struct wlr_renderer *wlr_vk_renderer_create_with_drm_fd(int drm_fd) {
+struct wlr_renderer *wlr_vk_renderer_create_with_drm_dev_id(dev_t dev_id) {
 	wlr_log(WLR_INFO, "The vulkan renderer is only experimental and "
 		"not expected to be ready for daily use");
 	wlr_log(WLR_INFO, "Run with VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation "
@@ -2205,7 +2205,7 @@ struct wlr_renderer *wlr_vk_renderer_create_with_drm_fd(int drm_fd) {
 		return NULL;
 	}
 
-	VkPhysicalDevice phdev = vulkan_find_drm_phdev(ini, drm_fd);
+	VkPhysicalDevice phdev = vulkan_find_drm_phdev(ini, dev_id);
 	if (!phdev) {
 		// We rather fail here than doing some guesswork
 		wlr_log(WLR_ERROR, "Could not match drm and vulkan device");

render/vulkan/vulkan.c

@@ -255,7 +255,7 @@ static void log_phdev(const VkPhysicalDeviceProperties *props) {
 	wlr_log(WLR_INFO, "  Driver version: %u.%u.%u", dv_major, dv_minor, dv_patch);
 }
 
-VkPhysicalDevice vulkan_find_drm_phdev(struct wlr_vk_instance *ini, int drm_fd) {
+VkPhysicalDevice vulkan_find_drm_phdev(struct wlr_vk_instance *ini, dev_t devid) {
 	VkResult res;
 	uint32_t num_phdevs;
 
@@ -272,12 +272,6 @@ VkPhysicalDevice vulkan_find_drm_phdev(struct wlr_vk_instance *ini, int drm_fd)
 		return VK_NULL_HANDLE;
 	}
 
-	struct stat drm_stat = {0};
-	if (fstat(drm_fd, &drm_stat) != 0) {
-		wlr_log_errno(WLR_ERROR, "fstat failed");
-		return VK_NULL_HANDLE;
-	}
-
 	for (uint32_t i = 0; i < num_phdevs; ++i) {
 		VkPhysicalDevice phdev = phdevs[i];
 
@@ -352,8 +346,7 @@ VkPhysicalDevice vulkan_find_drm_phdev(struct wlr_vk_instance *ini, int drm_fd)
 
 		dev_t primary_devid = makedev(drm_props.primaryMajor, drm_props.primaryMinor);
 		dev_t render_devid = makedev(drm_props.renderMajor, drm_props.renderMinor);
-		if (primary_devid == drm_stat.st_rdev ||
-				render_devid == drm_stat.st_rdev) {
+		if (primary_devid == devid || render_devid == devid) {
 			wlr_log(WLR_INFO, "Found matching Vulkan physical device: %s",
 				phdev_props.deviceName);
 			return phdev;

render/wlr_renderer.c

@@ -91,40 +91,41 @@ bool wlr_renderer_init_wl_display(struct wlr_renderer *r,
 	return true;
 }
 
-static int open_drm_render_node(void) {
+static bool pick_drm_render_node(dev_t *dev_id) {
 	uint32_t flags = 0;
 	int devices_len = drmGetDevices2(flags, NULL, 0);
 	if (devices_len < 0) {
 		wlr_log(WLR_ERROR, "drmGetDevices2 failed: %s", strerror(-devices_len));
-		return -1;
+		return false;
 	}
 	drmDevice **devices = calloc(devices_len, sizeof(*devices));
 	if (devices == NULL) {
 		wlr_log_errno(WLR_ERROR, "Allocation failed");
-		return -1;
+		return false;
 	}
 	devices_len = drmGetDevices2(flags, devices, devices_len);
 	if (devices_len < 0) {
 		free(devices);
 		wlr_log(WLR_ERROR, "drmGetDevices2 failed: %s", strerror(-devices_len));
-		return -1;
+		return false;
 	}
 
-	int fd = -1;
+	bool ok = false;
 	for (int i = 0; i < devices_len; i++) {
 		drmDevice *dev = devices[i];
 		if (dev->available_nodes & (1 << DRM_NODE_RENDER)) {
 			const char *name = dev->nodes[DRM_NODE_RENDER];
-			wlr_log(WLR_DEBUG, "Opening DRM render node '%s'", name);
-			fd = open(name, O_RDWR | O_CLOEXEC);
-			if (fd < 0) {
-				wlr_log_errno(WLR_ERROR, "Failed to open '%s'", name);
+			wlr_log(WLR_DEBUG, "Picking DRM render node '%s'", name);
+			struct stat st;
+			if (stat(name, &st) != 0) {
+				wlr_log_errno(WLR_ERROR, "stat() failed for %s", name);
 				goto out;
 			}
+			*dev_id = st.st_rdev;
 			break;
 		}
 	}
-	if (fd < 0) {
+	if (!ok) {
 		wlr_log(WLR_ERROR, "Failed to find any DRM render node");
 	}
 
@@ -134,15 +135,31 @@ out:
 	}
 	free(devices);
 
-	return fd;
+	return ok;
 }
 
-static bool open_preferred_drm_fd(struct wlr_backend *backend, int *drm_fd_ptr,
-		bool *own_drm_fd) {
-	if (*drm_fd_ptr >= 0) {
+static bool dev_id_from_fd(int fd, dev_t *dev_id, bool *has_dev_id) {
+	struct stat st;
+	if (fstat(fd, &st) != 0) {
+		wlr_log_errno(WLR_ERROR, "fstat() failed");
+		return false;
+	}
+	*dev_id = st.st_rdev;
+	*has_dev_id = true;
+	return true;
+}
+
+static bool get_preferred_drm_dev_id(struct wlr_backend *backend, int drm_fd,
+		dev_t *dev_id, bool *has_dev_id) {
+	if (*has_dev_id) {
 		return true;
 	}
 
+	// If the caller passed in a DRM FD, use that
+	if (drm_fd >= 0) {
+		return dev_id_from_fd(drm_fd, dev_id, has_dev_id);
+	}
+
 	// Allow the user to override the render node
 	const char *render_name = getenv("WLR_RENDER_DRM_DEVICE");
 	if (render_name != NULL) {
@@ -159,29 +176,25 @@ static bool open_preferred_drm_fd(struct wlr_backend *backend, int *drm_fd_ptr,
 			close(drm_fd);
 			return false;
 		}
-		*drm_fd_ptr = drm_fd;
-		*own_drm_fd = true;
-		return true;
+		bool ok = dev_id_from_fd(drm_fd, dev_id, has_dev_id);
+		close(drm_fd);
+		return ok;
 	}
 
 	// Prefer the backend's DRM node, if any
 	int backend_drm_fd = wlr_backend_get_drm_fd(backend);
 	if (backend_drm_fd >= 0) {
-		*drm_fd_ptr = backend_drm_fd;
-		*own_drm_fd = false;
-		return true;
+		return dev_id_from_fd(backend_drm_fd, dev_id, has_dev_id);
 	}
 
 	// If the backend hasn't picked a DRM FD, but accepts DMA-BUFs, pick an
 	// arbitrary render node
 	uint32_t backend_caps = backend_get_buffer_caps(backend);
 	if (backend_caps & WLR_BUFFER_CAP_DMABUF) {
-		int drm_fd = open_drm_render_node();
-		if (drm_fd < 0) {
+		if (!pick_drm_render_node(dev_id)) {
 			return false;
 		}
-		*drm_fd_ptr = drm_fd;
-		*own_drm_fd = true;
+		*has_dev_id = true;
 		return true;
 	}
 
@@ -222,14 +235,18 @@ static struct wlr_renderer *renderer_autocreate(struct wlr_backend *backend, int
 	bool is_auto = strcmp(renderer_name, "auto") == 0;
 	struct wlr_renderer *renderer = NULL;
 
-	bool own_drm_fd = false;
+	dev_t drm_dev_id;
+	bool has_drm_dev_id = false;
+	(void)drm_dev_id;
+	(void)has_drm_dev_id;
+	(void)get_preferred_drm_dev_id;
 
-	if ((is_auto && WLR_HAS_GLES2_RENDERER) || strcmp(renderer_name, "gles2") == 0) {
-		if (!open_preferred_drm_fd(backend, &drm_fd, &own_drm_fd)) {
-			log_creation_failure(is_auto, "Cannot create GLES2 renderer: no DRM FD available");
+	if (is_auto || strcmp(renderer_name, "gles2") == 0) {
+		if (!get_preferred_drm_dev_id(backend, drm_fd, &drm_dev_id, &has_drm_dev_id)) {
+			log_creation_failure(is_auto, "Cannot create GLES2 renderer: no DRM device available");
 		} else {
 #if WLR_HAS_GLES2_RENDERER
-			renderer = wlr_gles2_renderer_create_with_drm_fd(drm_fd);
+			renderer = wlr_gles2_renderer_create_with_drm_dev_id(drm_dev_id);
 #else
 			wlr_log(WLR_ERROR, "Cannot create GLES renderer: disabled at compile-time");
 #endif
@@ -242,11 +259,11 @@ static struct wlr_renderer *renderer_autocreate(struct wlr_backend *backend, int
 	}
 
 	if (strcmp(renderer_name, "vulkan") == 0) {
-		if (!open_preferred_drm_fd(backend, &drm_fd, &own_drm_fd)) {
-			log_creation_failure(is_auto, "Cannot create Vulkan renderer: no DRM FD available");
+		if (!get_preferred_drm_dev_id(backend, drm_fd, &drm_dev_id, &has_drm_dev_id)) {
+			log_creation_failure(is_auto, "Cannot create Vulkan renderer: no DRM device available");
 		} else {
 #if WLR_HAS_VULKAN_RENDERER
-			renderer = wlr_vk_renderer_create_with_drm_fd(drm_fd);
+			renderer = wlr_vk_renderer_create_with_drm_dev_id(drm_dev_id);
 #else
 			wlr_log(WLR_ERROR, "Cannot create Vulkan renderer: disabled at compile-time");
 #endif
@@ -271,9 +288,6 @@ out:
 	if (renderer == NULL) {
 		wlr_log(WLR_ERROR, "Could not initialize renderer");
 	}
-	if (own_drm_fd && drm_fd >= 0) {
-		close(drm_fd);
-	}
 	return renderer;
 }