[PATCH v6 15/22] drm/shmem-helper: Don't use vmap_use_count for dma-bufs

Dmitry Osipenko
2022-05-26T23:56:09Z

There is no need to refcount vmappings of dma-bufs because dma-buf core
has its own refcounting. Drop the refcounting of dma-bufs. This will ease
replacing of all drm-shmem locks with a single dma-buf reservation lock,
preparing drm-shmem code for addition of the generic drm-shmem shrinker.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 35 +++++++++++++++-----------
1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 7232e321fdb4..fd2647690bf7 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -293,24 +293,22 @@ 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 (WARN_ON(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;
@@ -376,15 +374,15 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
{
struct drm_gem_object *obj = &shmem->base;

- if (WARN_ON_ONCE(!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 (WARN_ON_ONCE(!shmem->vmap_use_count))
+ return;
+
+ if (--shmem->vmap_use_count > 0)
+ return;
+
vunmap(shmem->vaddr);
drm_gem_shmem_put_pages(shmem);
}
@@ -637,7 +635,14 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
struct drm_printer *p, unsigned int indent)
{
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);
+
+ if (shmem->base.import_attach)
+ drm_printf_indent(p, indent, "vmap_use_count=%u\n",
+ shmem->base.dma_buf->vmapping_counter);
+ else
+ drm_printf_indent(p, indent, "vmap_use_count=%u\n",
+ shmem->vmap_use_count);
+
drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
}
EXPORT_SYMBOL(drm_gem_shmem_print_info);
--
2.35.3