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Message-ID: <20230827175449.1766701-14-dmitry.osipenko@collabora.com>
Date: Sun, 27 Aug 2023 20:54:39 +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>,
Will Deacon <will@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Boqun Feng <boqun.feng@...il.com>,
Mark Rutland <mark.rutland@....com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
kernel@...labora.com, virtualization@...ts.linux-foundation.org,
intel-gfx@...ts.freedesktop.org
Subject: [PATCH v15 13/23] drm/shmem-helper: Use kref for pages_use_count
Use atomic kref helper for pages_use_count to optimize pin/unpin functions
by skipping reservation locking while GEM's pin refcount > 1.
Suggested-by: Boris Brezillon <boris.brezillon@...labora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 48 ++++++++++++++-----------
drivers/gpu/drm/lima/lima_gem.c | 2 +-
drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 +-
include/drm/drm_gem_shmem_helper.h | 2 +-
4 files changed, 30 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 1a7e5c332fd8..5a2e37b3e51d 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -155,7 +155,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
if (shmem->got_sgt)
drm_gem_shmem_put_pages_locked(shmem);
- drm_WARN_ON(obj->dev, shmem->pages_use_count);
+ drm_WARN_ON(obj->dev, kref_read(&shmem->pages_use_count));
dma_resv_unlock(shmem->base.resv);
}
@@ -172,14 +172,13 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
dma_resv_assert_held(shmem->base.resv);
- if (shmem->pages_use_count++ > 0)
+ if (kref_get_unless_zero(&shmem->pages_use_count))
return 0;
pages = drm_gem_get_pages(obj);
if (IS_ERR(pages)) {
drm_dbg_kms(obj->dev, "Failed to get pages (%ld)\n",
PTR_ERR(pages));
- shmem->pages_use_count = 0;
return PTR_ERR(pages);
}
@@ -195,26 +194,20 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
shmem->pages = pages;
+ kref_init(&shmem->pages_use_count);
+
return 0;
}
-/*
- * drm_gem_shmem_put_pages_locked - Decrease use count on the backing pages for a shmem GEM object
- * @shmem: shmem GEM object
- *
- * This function decreases the use count and puts the backing pages when use drops to zero.
- */
-void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
-{
- struct drm_gem_object *obj = &shmem->base;
-
- dma_resv_assert_held(shmem->base.resv);
- if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
- return;
+static void drm_gem_shmem_kref_release_pages(struct kref *kref)
+{
+ struct drm_gem_shmem_object *shmem;
+ struct drm_gem_object *obj;
- if (--shmem->pages_use_count > 0)
- return;
+ shmem = container_of(kref, struct drm_gem_shmem_object,
+ pages_use_count);
+ obj = &shmem->base;
#ifdef CONFIG_X86
if (shmem->map_wc)
@@ -226,6 +219,19 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
shmem->pages_mark_accessed_on_put);
shmem->pages = NULL;
}
+
+/*
+ * drm_gem_shmem_put_pages_locked - Decrease use count on the backing pages for a shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This function decreases the use count and puts the backing pages when use drops to zero.
+ */
+void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
+{
+ dma_resv_assert_held(shmem->base.resv);
+
+ kref_put(&shmem->pages_use_count, drm_gem_shmem_kref_release_pages);
+}
EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked);
static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
@@ -556,8 +562,8 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
* mmap'd, vm_open() just grabs an additional reference for the new
* mm the vma is getting copied into (ie. on fork()).
*/
- if (!drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
- shmem->pages_use_count++;
+ drm_WARN_ON_ONCE(obj->dev,
+ !kref_get_unless_zero(&shmem->pages_use_count));
dma_resv_unlock(shmem->base.resv);
@@ -638,7 +644,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
if (shmem->base.import_attach)
return;
- drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
+ drm_printf_indent(p, indent, "pages_use_count=%u\n", kref_read(&shmem->pages_use_count));
drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
}
diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
index 7d74c71f5558..a5f015d188cd 100644
--- a/drivers/gpu/drm/lima/lima_gem.c
+++ b/drivers/gpu/drm/lima/lima_gem.c
@@ -47,7 +47,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm)
}
bo->base.pages = pages;
- bo->base.pages_use_count = 1;
+ kref_init(&bo->base.pages_use_count);
mapping_set_unevictable(mapping);
}
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index 7771769f0ce0..c9ac9d361864 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -487,7 +487,7 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
goto err_unlock;
}
bo->base.pages = pages;
- bo->base.pages_use_count = 1;
+ kref_init(&bo->base.pages_use_count);
} else {
pages = bo->base.pages;
if (pages[page_offset]) {
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index afb7cd671e2a..a5a3c193cc8f 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -37,7 +37,7 @@ struct drm_gem_shmem_object {
* Reference count on the pages table.
* The pages are put when the count reaches zero.
*/
- unsigned int pages_use_count;
+ struct kref pages_use_count;
/**
* @pages_pin_count:
--
2.41.0
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