drm/shmem-helper: Don't use vmap_use_count for dma-bufs

DMA-buf core has its own refcounting of vmaps, use it instead of drm-shmem
counting. This change prepares drm-shmem for addition of memory shrinker
support where drm-shmem will use a single dma-buf reservation lock for
all operations performed over dma-bufs.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://lore.kernel.org/all/20230108210445.3948344-7-dmitry.osipenko@collabora.com/

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 0cc11adf989e5dc9b5f744316d1defc64acb0157..f75e50273d7a9ea395901c466d7bca744fd42c89 100644 (file)
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -301,24 +301,22 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
        struct drm_gem_object *obj = &shmem->base;
        int ret = 0;
 
-       if (shmem->vmap_use_count++ > 0) {
-               iosys_map_set_vaddr(map, shmem->vaddr);
-               return 0;
-       }
-
        if (obj->import_attach) {
                ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
                if (!ret) {
                        if (drm_WARN_ON(obj->dev, map->is_iomem)) {
                                dma_buf_vunmap(obj->import_attach->dmabuf, map);
-                               ret = -EIO;
-                               goto err_put_pages;
+                               return -EIO;
                        }
-                       shmem->vaddr = map->vaddr;
                }
        } else {
                pgprot_t prot = PAGE_KERNEL;
 
+               if (shmem->vmap_use_count++ > 0) {
+                       iosys_map_set_vaddr(map, shmem->vaddr);
+                       return 0;
+               }
+
                ret = drm_gem_shmem_get_pages(shmem);
                if (ret)
                        goto err_zero_use;
@@ -384,15 +382,15 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
 {
        struct drm_gem_object *obj = &shmem->base;
 
-       if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count))
-               return;
-
-       if (--shmem->vmap_use_count > 0)
-               return;
-
        if (obj->import_attach) {
                dma_buf_vunmap(obj->import_attach->dmabuf, map);
        } else {
+               if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count))
+                       return;
+
+               if (--shmem->vmap_use_count > 0)
+                       return;
+
                vunmap(shmem->vaddr);
                drm_gem_shmem_put_pages(shmem);
        }
@@ -654,6 +652,9 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
 void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
                              struct drm_printer *p, unsigned int indent)
 {
+       if (shmem->base.import_attach)
+               return;
+
        drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
        drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
        drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);