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Message-ID: <20250322212608.40511-9-dmitry.osipenko@collabora.com>
Date: Sun, 23 Mar 2025 00:26:06 +0300
From: Dmitry Osipenko <dmitry.osipenko@...labora.com>
To: David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
Christian König <christian.koenig@....com>,
Gerd Hoffmann <kraxel@...hat.com>,
Qiang Yu <yuq825@...il.com>,
Steven Price <steven.price@....com>,
Boris Brezillon <boris.brezillon@...labora.com>,
Frank Binns <frank.binns@...tec.com>,
Matt Coster <matt.coster@...tec.com>
Cc: dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org,
kernel@...labora.com
Subject: [PATCH v20 08/10] drm/shmem-helper: Use refcount_t for pages_use_count
Use atomic refcount_t helper for pages_use_count to optimize pin/unpin
functions by skipping reservation locking while GEM's pin refcount > 1.
Acked-by: Maxime Ripard <mripard@...nel.org>
Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
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 | 33 ++++++++++------------
drivers/gpu/drm/lima/lima_gem.c | 2 +-
drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 +-
drivers/gpu/drm/tests/drm_gem_shmem_test.c | 8 +++---
include/drm/drm_gem_shmem_helper.h | 2 +-
5 files changed, 22 insertions(+), 25 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index d338b36f4eaa..6fb96e790abd 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -176,7 +176,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
if (shmem->pages)
drm_gem_shmem_put_pages_locked(shmem);
- drm_WARN_ON(obj->dev, shmem->pages_use_count);
+ drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_use_count));
drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_pin_count));
dma_resv_unlock(shmem->base.resv);
@@ -194,14 +194,13 @@ 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 (refcount_inc_not_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);
}
@@ -217,6 +216,8 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
shmem->pages = pages;
+ refcount_set(&shmem->pages_use_count, 1);
+
return 0;
}
@@ -232,21 +233,17 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
dma_resv_assert_held(shmem->base.resv);
- if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
- return;
-
- if (--shmem->pages_use_count > 0)
- return;
-
+ if (refcount_dec_and_test(&shmem->pages_use_count)) {
#ifdef CONFIG_X86
- if (shmem->map_wc)
- set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
+ if (shmem->map_wc)
+ set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
#endif
- drm_gem_put_pages(obj, shmem->pages,
- shmem->pages_mark_dirty_on_put,
- shmem->pages_mark_accessed_on_put);
- shmem->pages = NULL;
+ drm_gem_put_pages(obj, shmem->pages,
+ shmem->pages_mark_dirty_on_put,
+ shmem->pages_mark_accessed_on_put);
+ shmem->pages = NULL;
+ }
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked);
@@ -582,8 +579,8 @@ 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,
+ !refcount_inc_not_zero(&shmem->pages_use_count));
dma_resv_unlock(shmem->base.resv);
@@ -674,7 +671,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
return;
drm_printf_indent(p, indent, "pages_pin_count=%u\n", refcount_read(&shmem->pages_pin_count));
- drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
+ drm_printf_indent(p, indent, "pages_use_count=%u\n", refcount_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 609221351cde..5deec673c11e 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;
+ refcount_set(&bo->base.pages_use_count, 1);
mapping_set_unevictable(mapping);
}
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index b91019cd5acb..4a0b4bf03f1a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -489,7 +489,7 @@ 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;
+ refcount_set(&bo->base.pages_use_count, 1);
} else {
pages = bo->base.pages;
if (pages[page_offset]) {
diff --git a/drivers/gpu/drm/tests/drm_gem_shmem_test.c b/drivers/gpu/drm/tests/drm_gem_shmem_test.c
index 98884966bb92..1459cdb0c413 100644
--- a/drivers/gpu/drm/tests/drm_gem_shmem_test.c
+++ b/drivers/gpu/drm/tests/drm_gem_shmem_test.c
@@ -134,7 +134,7 @@ static void drm_gem_shmem_test_pin_pages(struct kunit *test)
shmem = drm_gem_shmem_create(drm_dev, TEST_SIZE);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, shmem);
KUNIT_EXPECT_NULL(test, shmem->pages);
- KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 0);
+ KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 0);
ret = kunit_add_action_or_reset(test, drm_gem_shmem_free_wrapper, shmem);
KUNIT_ASSERT_EQ(test, ret, 0);
@@ -142,14 +142,14 @@ static void drm_gem_shmem_test_pin_pages(struct kunit *test)
ret = drm_gem_shmem_pin(shmem);
KUNIT_ASSERT_EQ(test, ret, 0);
KUNIT_ASSERT_NOT_NULL(test, shmem->pages);
- KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 1);
+ KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 1);
for (i = 0; i < (shmem->base.size >> PAGE_SHIFT); i++)
KUNIT_ASSERT_NOT_NULL(test, shmem->pages[i]);
drm_gem_shmem_unpin(shmem);
KUNIT_EXPECT_NULL(test, shmem->pages);
- KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 0);
+ KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 0);
}
/*
@@ -251,7 +251,7 @@ static void drm_gem_shmem_test_get_sg_table(struct kunit *test)
sgt = drm_gem_shmem_get_pages_sgt(shmem);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, sgt);
KUNIT_ASSERT_NOT_NULL(test, shmem->pages);
- KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 1);
+ KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 1);
KUNIT_EXPECT_PTR_EQ(test, sgt, shmem->sgt);
for_each_sgtable_sg(sgt, sg, si) {
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index d411215fe494..3a4be433d5f0 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;
+ refcount_t pages_use_count;
/**
* @pages_pin_count:
--
2.49.0
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