[PATCH v9 06/11] drm/shmem-helper: Don't use vmap_use_count for dma-bufs

From: Dmitry Osipenko <dmitry.osipenko@collabora.com>
To: "David Airlie" <airlied@gmail.com>,
	"Gerd Hoffmann" <kraxel@redhat.com>,
	"Gurchetan Singh" <gurchetansingh@chromium.org>,
	"Chia-I Wu" <olvaffe@gmail.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Daniel Almeida" <daniel.almeida@collabora.com>,
	"Gustavo Padovan" <gustavo.padovan@collabora.com>,
	"Daniel Stone" <daniel@fooishbar.org>,
	"Tomeu Vizoso" <tomeu.vizoso@collabora.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Rob Clark" <robdclark@gmail.com>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Qiang Yu" <yuq825@gmail.com>,
	"Steven Price" <steven.price@arm.com>,
	"Alyssa Rosenzweig" <alyssa.rosenzweig@collabora.com>,
	"Rob Herring" <robh@kernel.org>, "Sean Paul" <sean@poorly.run>,
	"Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
	"Abhinav Kumar" <quic_abhinavk@quicinc.com>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	kernel@collabora.com, virtualization@lists.linux-foundation.org
Subject: [PATCH v9 06/11] drm/shmem-helper: Don't use vmap_use_count for dma-bufs
Date: Wed, 23 Nov 2022 05:57:18 +0300	[thread overview]
Message-ID: <20221123025723.695075-7-dmitry.osipenko@collabora.com> (raw)
In-Reply-To: <20221123025723.695075-1-dmitry.osipenko@collabora.com>

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.

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 5504eeb61099..ba9d9c5f1064 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -299,24 +299,22 @@ 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;
@@ -382,15 +380,15 @@ 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);
 	}
@@ -652,7 +650,14 @@ 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);
-- 
2.38.1

