linux-kernel - [PATCH v19 16/30] drm/lima: Explicitly get and put drm-shmem pages

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Date: Fri,  5 Jan 2024 21:46:10 +0300
From: Dmitry Osipenko <dmitry.osipenko@...labora.com>
To: David Airlie <airlied@...il.com>,
	Gerd Hoffmann <kraxel@...hat.com>,
	Gurchetan Singh <gurchetansingh@...omium.org>,
	Chia-I Wu <olvaffe@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Christian König <christian.koenig@....com>,
	Qiang Yu <yuq825@...il.com>,
	Steven Price <steven.price@....com>,
	Boris Brezillon <boris.brezillon@...labora.com>,
	Emma Anholt <emma@...olt.net>,
	Melissa Wen <mwen@...lia.com>
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	kernel@...labora.com,
	virtualization@...ts.linux-foundation.org
Subject: [PATCH v19 16/30] drm/lima: Explicitly get and put drm-shmem pages

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@...labora.com>
---
 drivers/gpu/drm/lima/lima_gem.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
index 2a97aa85416b..9c3e34a7fbed 100644
--- a/drivers/gpu/drm/lima/lima_gem.c
+++ b/drivers/gpu/drm/lima/lima_gem.c
@@ -115,6 +115,7 @@ 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 +124,17 @@ 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;
+
+		sgt = drm_gem_shmem_get_pages_sgt(shmem);
 		if (IS_ERR(sgt)) {
 			err = PTR_ERR(sgt);
 			goto out;
@@ -139,6 +144,9 @@ int lima_gem_create_handle(struct drm_device *dev, struct drm_file *file,
 	err = drm_gem_handle_create(file, obj, handle);
 
 out:
+	if (err && refcount_read(&bo->base.pages_use_count))
+		drm_gem_shmem_put_pages(shmem);
+
 	/* drop reference from allocate - handle holds it now */
 	drm_gem_object_put(obj);
 
@@ -152,6 +160,9 @@ 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 (refcount_read(&bo->base.pages_use_count))
+		drm_gem_shmem_put_pages(&bo->base);
+
 	drm_gem_shmem_free(&bo->base);
 }
 
-- 
2.43.0