[Linaro-mm-sig] Re: [PATCH 06/10] dma-buf/selftests: test RCU ops and inline lock v2

On 13/01/2026 15:16, Christian König wrote:

Drop the mock_fence and the kmem_cache, instead use the inline lock and test if the ops are properly dropped after signaling.

v2: move the RCU check to the end of the test

Signed-off-by: Christian König christian.koenig@amd.com

drivers/dma-buf/st-dma-fence.c | 44 ++++++++-------------------------- 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/drivers/dma-buf/st-dma-fence.c b/drivers/dma-buf/st-dma-fence.c index 5d0d9abc6e21..0d9d524d79b6 100644 --- a/drivers/dma-buf/st-dma-fence.c +++ b/drivers/dma-buf/st-dma-fence.c @@ -14,43 +14,26 @@ #include "selftest.h" -static struct kmem_cache *slab_fences;

-static struct mock_fence {

• struct dma_fence base;
• struct spinlock lock;

-} *to_mock_fence(struct dma_fence *f) {

• return container_of(f, struct mock_fence, base);

-}

• static const char *mock_name(struct dma_fence *f) { return "mock"; }

-static void mock_fence_release(struct dma_fence *f) -{

• kmem_cache_free(slab_fences, to_mock_fence(f));

-}

• static const struct dma_fence_ops mock_ops = { .get_driver_name = mock_name, .get_timeline_name = mock_name,
• .release = mock_fence_release, };

static struct dma_fence *mock_fence(void) {

• struct mock_fence *f;

• struct dma_fence *f;

• f = kmem_cache_alloc(slab_fences, GFP_KERNEL);

• f = kmalloc(sizeof(*f), GFP_KERNEL); if (!f) return NULL;

• spin_lock_init(&f->lock);
• dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
• return &f->base;

• dma_fence_init(f, &mock_ops, NULL, 0, 0);
• return f; }

static int sanitycheck(void *arg) @@ -100,6 +83,11 @@ static int test_signaling(void *arg) goto err_free; }

• if (rcu_dereference_protected(f->ops, true)) {

• pr_err("Fence ops not cleared on signal\n");
  

• goto err_free;
  

• }
• err = 0; err_free: dma_fence_put(f);

@@ -540,19 +528,7 @@ int dma_fence(void) SUBTEST(test_stub), SUBTEST(race_signal_callback), };

• int ret;

pr_info("sizeof(dma_fence)=%zu\n", sizeof(struct dma_fence));

• slab_fences = KMEM_CACHE(mock_fence,

• 		 SLAB_TYPESAFE_BY_RCU |
  

• 		 SLAB_HWCACHE_ALIGN);
  

• if (!slab_fences)

• return -ENOMEM;
  

• ret = subtests(tests, NULL);
• kmem_cache_destroy(slab_fences);
• return ret;

• return subtests(tests, NULL); }

Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@igalia.com

Regards,

Tvrtko