A bug inside the new sync-file merge code created empty dma_fence_array instances.

Warn about that and handle those without crashing.

Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-fence-array.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c index 52b85d292383..5c8a7084577b 100644 --- a/drivers/dma-buf/dma-fence-array.c +++ b/drivers/dma-buf/dma-fence-array.c @@ -159,6 +159,8 @@ struct dma_fence_array *dma_fence_array_create(int num_fences, struct dma_fence_array *array; size_t size = sizeof(*array);

+ WARN_ON(!num_fences || !fences); + /* Allocate the callback structures behind the array. */ size += num_fences * sizeof(struct dma_fence_array_cb); array = kzalloc(size, GFP_KERNEL); @@ -231,6 +233,9 @@ struct dma_fence *dma_fence_array_first(struct dma_fence *head) if (!array) return head;

+ if (!array->num_fences) + return NULL; + return array->fences[0]; } EXPORT_SYMBOL(dma_fence_array_first);

On Tue, Mar 29, 2022 at 09:00:00AM +0200, Christian König wrote:

When the array is empty because everything is signaled we can't use add_fence() to add something because that would filter the signaled fence again.

Signed-off-by: Christian König christian.koenig@amd.com Fixes: 519f490db07e ("dma-buf/sync-file: fix warning about fence containers")

---

drivers/dma-buf/sync_file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index b8dea4ec123b..514d213261df 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -262,7 +262,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, }

if (index == 0)

• add_fence(fences, &index, dma_fence_get_stub());
  

• fences[index++] = dma_fence_get_stub();
  

Uh idiot me wondered about this and somehow convinced myself that adding a random fences instead of a singalled stub is ok. I should have checked more carefully :-/

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

if (num_fences > index) { struct dma_fence **tmp; -- 2.25.1

I finally managed to find a machine and tested this series. If it is not too late

The series is Tested-by: Nirmoy Das nirmoy.das@intel.com

On 3/29/2022 9:00 AM, Christian König wrote:

When the array is empty because everything is signaled we can't use add_fence() to add something because that would filter the signaled fence again.

Signed-off-by: Christian König christian.koenig@amd.com Fixes: 519f490db07e ("dma-buf/sync-file: fix warning about fence containers")

---

drivers/dma-buf/sync_file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index b8dea4ec123b..514d213261df 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -262,7 +262,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, }

if (index == 0)

• add_fence(fences, &index, dma_fence_get_stub());
  

• fences[index++] = dma_fence_get_stub();
  
  

  if (num_fences > index) { struct dma_fence **tmp;