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drm/shmem-helper: Use refcount_t for vmap_use_count

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Use refcount_t helper for vmap_use_count to make refcounting consistent
with pages_use_count and pages_pin_count that use refcount_t. This also
makes vmapping to benefit from the refcount_t's overflow checks.

Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.d>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250322212608.40511-11-dmitry.osipenko@collabora.com
This commit is contained in:
Dmitry Osipenko 2025-03-23 00:26:08 +03:00
parent 0271cc484f
commit e1fc39a923
3 changed files with 16 additions and 20 deletions
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28
drivers/gpu/drm/drm_gem_shmem_helper.c
View File

@ -165,7 +165,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
} else {
dma_resv_lock(shmem->base.resv, NULL);
drm_WARN_ON(obj->dev, shmem->vmap_use_count);
drm_WARN_ON(obj->dev, refcount_read(&shmem->vmap_use_count));
if (shmem->sgt) {
dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
@ -355,23 +355,25 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
dma_resv_assert_held(shmem->base.resv);
if (shmem->vmap_use_count++ > 0) {
if (refcount_inc_not_zero(&shmem->vmap_use_count)) {
iosys_map_set_vaddr(map, shmem->vaddr);
return 0;
}
ret = drm_gem_shmem_pin_locked(shmem);
if (ret)
goto err_zero_use;
return ret;
if (shmem->map_wc)
prot = pgprot_writecombine(prot);
shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
VM_MAP, prot);
if (!shmem->vaddr)
if (!shmem->vaddr) {
ret = -ENOMEM;
else
} else {
iosys_map_set_vaddr(map, shmem->vaddr);
refcount_set(&shmem->vmap_use_count, 1);
}
}
if (ret) {
@ -384,8 +386,6 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
err_put_pages:
if (!drm_gem_is_imported(obj))
drm_gem_shmem_unpin_locked(shmem);
err_zero_use:
shmem->vmap_use_count = 0;
return ret;
}
@ -413,14 +413,10 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
} else {
dma_resv_assert_held(shmem->base.resv);
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_unpin_locked(shmem);
if (refcount_dec_and_test(&shmem->vmap_use_count)) {
vunmap(shmem->vaddr);
drm_gem_shmem_unpin_locked(shmem);
}
}
shmem->vaddr = NULL;
@ -672,7 +668,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
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", 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, "vmap_use_count=%u\n", refcount_read(&shmem->vmap_use_count));
drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_print_info);

6
drivers/gpu/drm/tests/drm_gem_shmem_test.c
View File

@ -168,7 +168,7 @@ static void drm_gem_shmem_test_vmap(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->vaddr);
KUNIT_EXPECT_EQ(test, shmem->vmap_use_count, 0);
KUNIT_EXPECT_EQ(test, refcount_read(&shmem->vmap_use_count), 0);
ret = kunit_add_action_or_reset(test, drm_gem_shmem_free_wrapper, shmem);
KUNIT_ASSERT_EQ(test, ret, 0);
@ -177,7 +177,7 @@ static void drm_gem_shmem_test_vmap(struct kunit *test)
KUNIT_ASSERT_EQ(test, ret, 0);
KUNIT_ASSERT_NOT_NULL(test, shmem->vaddr);
KUNIT_ASSERT_FALSE(test, iosys_map_is_null(&map));
KUNIT_EXPECT_EQ(test, shmem->vmap_use_count, 1);
KUNIT_EXPECT_EQ(test, refcount_read(&shmem->vmap_use_count), 1);
iosys_map_memset(&map, 0, TEST_BYTE, TEST_SIZE);
for (i = 0; i < TEST_SIZE; i++)
@ -185,7 +185,7 @@ static void drm_gem_shmem_test_vmap(struct kunit *test)
drm_gem_shmem_vunmap_locked(shmem, &map);
KUNIT_EXPECT_NULL(test, shmem->vaddr);
KUNIT_EXPECT_EQ(test, shmem->vmap_use_count, 0);
KUNIT_EXPECT_EQ(test, refcount_read(&shmem->vmap_use_count), 0);
}
/*

2
include/drm/drm_gem_shmem_helper.h
View File

@ -82,7 +82,7 @@ struct drm_gem_shmem_object {
* Reference count on the virtual address.
* The address are un-mapped when the count reaches zero.
*/
unsigned int vmap_use_count;
refcount_t vmap_use_count;
/**
* @pages_mark_dirty_on_put: