winsys/nouveau: Rework to use u_pipe_screen_lookup_or_create

All the boilerplate can be removed to use u_pipe_screen_lookup_or_create
instead.

Signed-off-by: Mary Guillemard <mary@mary.zone>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31667>

src/gallium/drivers/nouveau/nouveau_screen.c

@@ -317,12 +317,7 @@ nouveau_screen_init(struct nouveau_screen *screen, struct nouveau_device *dev)
     */
    screen->drm = nouveau_drm(&dev->object);
    screen->device = dev;
-
-   /*
-    * this is initialized to 1 in nouveau_drm_screen_create after screen
-    * is fully constructed and added to the global screen list.
-    */
-   screen->refcount = -1;
+   screen->initialized = false;
 
    if (dev->chipset < 0xc0) {
       data = &nv04_data;

src/gallium/drivers/nouveau/nouveau_screen.h

@@ -32,7 +32,7 @@ struct nouveau_screen {
 
    char chipset_name[8];
 
-   int refcount;
+   bool initialized;
 
    unsigned transfer_pushbuf_threshold;
 
@@ -137,8 +137,6 @@ nouveau_screen(struct pipe_screen *pscreen)
    return (struct nouveau_screen *)pscreen;
 }
 
-bool nouveau_drm_screen_unref(struct nouveau_screen *screen);
-
 bool
 nouveau_screen_bo_get_handle(struct pipe_screen *pscreen,
                              struct nouveau_bo *bo,

src/gallium/drivers/nouveau/nv30/nv30_screen.c

@@ -534,7 +534,7 @@ nv30_screen_destroy(struct pipe_screen *pscreen)
 {
    struct nv30_screen *screen = nv30_screen(pscreen);
 
-   if (!nouveau_drm_screen_unref(&screen->base))
+   if (!screen->base.initialized)
       return;
 
    nouveau_bo_ref(NULL, &screen->notify);

src/gallium/drivers/nouveau/nv50/nv50_screen.c

@@ -472,7 +472,7 @@ nv50_screen_destroy(struct pipe_screen *pscreen)
 {
    struct nv50_screen *screen = nv50_screen(pscreen);
 
-   if (!nouveau_drm_screen_unref(&screen->base))
+   if (!screen->base.initialized)
       return;
 
    if (screen->blitter)

src/gallium/drivers/nouveau/nvc0/nvc0_screen.c

@@ -608,7 +608,7 @@ nvc0_screen_destroy(struct pipe_screen *pscreen)
 {
    struct nvc0_screen *screen = nvc0_screen(pscreen);
 
-   if (!nouveau_drm_screen_unref(&screen->base))
+   if (!screen->base.initialized)
       return;
 
    if (screen->blitter)

src/gallium/winsys/nouveau/drm/nouveau_drm_public.h

@@ -3,6 +3,8 @@
 #define __NOUVEAU_DRM_PUBLIC_H__
 
 struct pipe_screen;
+struct pipe_screen_config;
+struct renderonly;
 
 struct pipe_screen *nouveau_drm_screen_create(int drmFD);
 

src/gallium/winsys/nouveau/drm/nouveau_drm_winsys.c

@@ -1,87 +1,34 @@
-#include <sys/stat.h>
 #include <unistd.h>
-#include <fcntl.h>
-#include "pipe/p_context.h"
-#include "pipe/p_state.h"
+
 #include "util/format/u_format.h"
 #include "util/os_file.h"
-#include "util/simple_mtx.h"
+#include "util/u_debug.h"
 #include "util/u_memory.h"
-#include "util/u_inlines.h"
-#include "util/u_hash_table.h"
-#include "util/u_pointer.h"
-#include "util/u_thread.h"
+#include "util/u_screen.h"
 
+#include "renderonly/renderonly.h"
 #include "nouveau_drm_public.h"
 
 #include "nouveau/nouveau_winsys.h"
 #include "nouveau/nouveau_screen.h"
 
-#include "nvif/class.h"
-#include "nvif/cl0080.h"
-
-static struct hash_table *fd_tab = NULL;
-
-static simple_mtx_t nouveau_screen_mutex = SIMPLE_MTX_INITIALIZER;
-
-bool nouveau_drm_screen_unref(struct nouveau_screen *screen)
-{
-	int ret;
-	if (screen->refcount == -1)
-		return true;
-
-	simple_mtx_lock(&nouveau_screen_mutex);
-	ret = --screen->refcount;
-	assert(ret >= 0);
-	if (ret == 0)
-		_mesa_hash_table_remove_key(fd_tab, intptr_to_pointer(screen->drm->fd));
-	simple_mtx_unlock(&nouveau_screen_mutex);
-	return ret == 0;
-}
-
-PUBLIC struct pipe_screen *
-nouveau_drm_screen_create(int fd)
+static struct pipe_screen *
+nouveau_screen_create(int fd, const struct pipe_screen_config *config,
+					  struct renderonly *ro)
 {
 	struct nouveau_drm *drm = NULL;
 	struct nouveau_device *dev = NULL;
 	struct nouveau_screen *(*init)(struct nouveau_device *);
 	struct nouveau_screen *screen = NULL;
-	int ret, dupfd;
+	int ret;
 
-	simple_mtx_lock(&nouveau_screen_mutex);
-	if (!fd_tab) {
-		fd_tab = util_hash_table_create_fd_keys();
-		if (!fd_tab) {
-			simple_mtx_unlock(&nouveau_screen_mutex);
-			return NULL;
-		}
-	}
-
-	screen = util_hash_table_get(fd_tab, intptr_to_pointer(fd));
-	if (screen) {
-		screen->refcount++;
-		simple_mtx_unlock(&nouveau_screen_mutex);
-		return &screen->base;
-	}
-
-	/* Since the screen re-use is based on the device node and not the fd,
-	 * create a copy of the fd to be owned by the device. Otherwise a
-	 * scenario could occur where two screens are created, and the first
-	 * one is shut down, along with the fd being closed. The second
-	 * (identical) screen would now have a reference to the closed fd. We
-	 * avoid this by duplicating the original fd. Note that
-	 * nouveau_device_wrap does not close the fd in case of a device
-	 * creation error.
-	 */
-	dupfd = os_dupfd_cloexec(fd);
-
-	ret = nouveau_drm_new(dupfd, &drm);
+	ret = nouveau_drm_new(fd, &drm);
 	if (ret)
-		goto err;
+		return NULL;
 
 	ret = nouveau_device_new(&drm->client, &dev);
 	if (ret)
-		goto err;
+		goto err_dev_new;
 
 	switch (dev->chipset & ~0xf) {
 	case 0x30:
@@ -111,31 +58,34 @@ nouveau_drm_screen_create(int fd)
 		break;
 	default:
 		debug_printf("%s: unknown chipset nv%02x\n", __func__,
-			     dev->chipset);
-		goto err;
+					 dev->chipset);
+		goto err_screen_create;
 	}
 
 	screen = init(dev);
-	if (!screen || !screen->base.context_create)
-		goto err;
+	if (!screen)
+		goto err_screen_create;
 
-	/* Use dupfd in hash table, to avoid errors if the original fd gets
-	 * closed by its owner. The hash key needs to live at least as long as
-	 * the screen.
-	 */
-	_mesa_hash_table_insert(fd_tab, intptr_to_pointer(dupfd), screen);
-	screen->refcount = 1;
-	simple_mtx_unlock(&nouveau_screen_mutex);
+	if (!screen->base.context_create)
+		goto err_screen_init;
+
+	screen->initialized = true;
 	return &screen->base;
 
-err:
-	if (screen) {
-		screen->base.destroy(&screen->base);
-	} else {
-		nouveau_device_del(&dev);
-		nouveau_drm_del(&drm);
-		close(dupfd);
-	}
-	simple_mtx_unlock(&nouveau_screen_mutex);
+err_screen_init:
+	screen->base.destroy(&screen->base);
+	return NULL;
+
+err_screen_create:
+	nouveau_device_del(&dev);
+err_dev_new:
+	nouveau_drm_del(&drm);
 	return NULL;
 }
+
+PUBLIC struct pipe_screen *
+nouveau_drm_screen_create(int fd)
+{
+	return u_pipe_screen_lookup_or_create(os_dupfd_cloexec(fd), NULL, NULL,
+										  nouveau_screen_create);
+}