On 13/11/2025 14:51, Christian König wrote:
When neither a release nor a wait backend ops is specified it is possible to let the dma_fence live on independently of the module who issued it.
This makes it possible to unload drivers and only wait for all their fences to signal.
v2: fix typo in comment
Signed-off-by: Christian König christian.koenig@amd.com
drivers/dma-buf/dma-fence.c | 16 ++++++++++++---- include/linux/dma-fence.h | 4 ++-- 2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index ec21be9b089a..7074347f506d 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -374,6 +374,14 @@ int dma_fence_signal_timestamp_locked(struct dma_fence *fence, &fence->flags))) return -EINVAL;
- /*
* When neither a release nor a wait operation is specified set the ops* pointer to NULL to allow the fence structure to become independent* from who originally issued it.*/- if (!fence->ops->release && !fence->ops->wait)
RCU_INIT_POINTER(fence->ops, NULL);- /* Stash the cb_list before replacing it with the timestamp */ list_replace(&fence->cb_list, &cb_list);
@@ -513,7 +521,7 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) rcu_read_lock(); ops = rcu_dereference(fence->ops); trace_dma_fence_wait_start(fence);
- if (ops->wait) {
- if (ops && ops->wait) { /*
- Implementing the wait ops is deprecated and not supported for
- issuer independent fences, so it is ok to use the ops outside
@@ -578,7 +586,7 @@ void dma_fence_release(struct kref *kref) } ops = rcu_dereference(fence->ops);
- if (ops->release)
- if (ops && ops->release) ops->release(fence); else dma_fence_free(fence);
@@ -614,7 +622,7 @@ static bool __dma_fence_enable_signaling(struct dma_fence *fence) rcu_read_lock(); ops = rcu_dereference(fence->ops);
- if (!was_set && ops->enable_signaling) {
- if (!was_set && ops && ops->enable_signaling) { trace_dma_fence_enable_signal(fence);
if (!ops->enable_signaling(fence)) { @@ -1000,7 +1008,7 @@ void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline) rcu_read_lock(); ops = rcu_dereference(fence->ops);
- if (ops->set_deadline && !dma_fence_is_signaled(fence))
- if (ops && ops->set_deadline && !dma_fence_is_signaled(fence)) ops->set_deadline(fence, deadline); rcu_read_unlock(); }
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 77f07735f556..eb57bcc8712f 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -436,7 +436,7 @@ dma_fence_is_signaled_locked(struct dma_fence *fence) rcu_read_lock(); ops = rcu_dereference(fence->ops);
- if (ops->signaled && ops->signaled(fence)) {
- if (ops && ops->signaled && ops->signaled(fence)) { rcu_read_unlock(); dma_fence_signal_locked(fence); return true;
@@ -472,7 +472,7 @@ dma_fence_is_signaled(struct dma_fence *fence) rcu_read_lock(); ops = rcu_dereference(fence->ops);
- if (ops->signaled && ops->signaled(fence)) {
- if (ops && ops->signaled && ops->signaled(fence)) { rcu_read_unlock(); dma_fence_signal(fence); return true;
Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@igalia.com
Regards,
Tvrtko