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From:   Dmitry Osipenko <dmitry.osipenko@collabora.com>
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Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Dmitry Osipenko <digetx@gmail.com>,
        Dmitry Osipenko <dmitry.osipenko@collabora.com>,
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Subject: [PATCH v6 15/22] drm/shmem-helper: Don't use vmap_use_count for dma-bufs
Date:   Fri, 27 May 2022 02:50:33 +0300
Message-Id: <20220526235040.678984-16-dmitry.osipenko@collabora.com>
In-Reply-To: <20220526235040.678984-1-dmitry.osipenko@collabora.com>
References: <20220526235040.678984-1-dmitry.osipenko@collabora.com>
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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