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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>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        Qiang Yu <yuq825@gmail.com>,
        Steven Price <steven.price@arm.com>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        Emma Anholt <emma@anholt.net>, Melissa Wen <mwen@igalia.com>
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        kernel@collabora.com, virtualization@lists.linux-foundation.org
Subject: [PATCH v18 14/26] drm/lima: Explicitly get and put drm-shmem pages
Date:   Mon, 30 Oct 2023 02:01:53 +0300
Message-ID: <20231029230205.93277-15-dmitry.osipenko@collabora.com>
In-Reply-To: <20231029230205.93277-1-dmitry.osipenko@collabora.com>
References: <20231029230205.93277-1-dmitry.osipenko@collabora.com>
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To simplify the drm-shmem refcnt handling, we're moving away from
the implicit get_pages() that is used by get_pages_sgt(). From now on
drivers will have to pin pages while they use sgt. Lima driver doesn't
have shrinker, hence pages are pinned and sgt is valid as long as pages'
use-count > 0.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
 drivers/gpu/drm/lima/lima_gem.c | 18 ++++++++++++++++--
 drivers/gpu/drm/lima/lima_gem.h |  1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
index 988e74f67465..d255f5775dac 100644
--- a/drivers/gpu/drm/lima/lima_gem.c
+++ b/drivers/gpu/drm/lima/lima_gem.c
@@ -46,6 +46,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm)
 			return -ENOMEM;
 		}
 
+		bo->put_pages = true;
 		bo->base.pages = pages;
 		refcount_set(&bo->base.pages_use_count, 1);
 
@@ -115,6 +116,7 @@ int lima_gem_create_handle(struct drm_device *dev, struct drm_file *file,
 		return PTR_ERR(shmem);
 
 	obj = &shmem->base;
+	bo = to_lima_bo(obj);
 
 	/* Mali Utgard GPU can only support 32bit address space */
 	mask = mapping_gfp_mask(obj->filp->f_mapping);
@@ -123,13 +125,19 @@ int lima_gem_create_handle(struct drm_device *dev, struct drm_file *file,
 	mapping_set_gfp_mask(obj->filp->f_mapping, mask);
 
 	if (is_heap) {
-		bo = to_lima_bo(obj);
 		err = lima_heap_alloc(bo, NULL);
 		if (err)
 			goto out;
 	} else {
-		struct sg_table *sgt = drm_gem_shmem_get_pages_sgt(shmem);
+		struct sg_table *sgt;
+
+		err = drm_gem_shmem_get_pages(shmem);
+		if (err)
+			goto out;
+
+		bo->put_pages = true;
 
+		sgt = drm_gem_shmem_get_pages_sgt(shmem);
 		if (IS_ERR(sgt)) {
 			err = PTR_ERR(sgt);
 			goto out;
@@ -139,6 +147,9 @@ int lima_gem_create_handle(struct drm_device *dev, struct drm_file *file,
 	err = drm_gem_handle_create(file, obj, handle);
 
 out:
+	if (err && bo->put_pages)
+		drm_gem_shmem_put_pages(shmem);
+
 	/* drop reference from allocate - handle holds it now */
 	drm_gem_object_put(obj);
 
@@ -152,6 +163,9 @@ static void lima_gem_free_object(struct drm_gem_object *obj)
 	if (!list_empty(&bo->va))
 		dev_err(obj->dev->dev, "lima gem free bo still has va\n");
 
+	if (bo->put_pages)
+		drm_gem_shmem_put_pages(&bo->base);
+
 	drm_gem_shmem_free(&bo->base);
 }
 
diff --git a/drivers/gpu/drm/lima/lima_gem.h b/drivers/gpu/drm/lima/lima_gem.h
index ccea06142f4b..dc5a6d465c80 100644
--- a/drivers/gpu/drm/lima/lima_gem.h
+++ b/drivers/gpu/drm/lima/lima_gem.h
@@ -16,6 +16,7 @@ struct lima_bo {
 	struct list_head va;
 
 	size_t heap_size;
+	bool put_pages;
 };
 
 static inline struct lima_bo *
-- 
2.41.0