[PATCH v2 05/14] drm/i915: Deconstruct execute fence

Chris Wilson
2017-02-14T09:54:24Z

On reflection, we are only using the execute fence as a waitqueue on the
global_seqno and not using it for dependency tracking between fences
(unlike the submit and dma fences). By only treating it as a waitqueue,
we can then treat it similar to the other waitqueues durin submit,
making the code simpler.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_request.c | 47 +++++++--------------------------
drivers/gpu/drm/i915/i915_gem_request.h | 10 +------
2 files changed, 11 insertions(+), 46 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 001fc9fedf49..bb59acaa8a34 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -69,7 +69,6 @@ static void i915_fence_release(struct dma_fence *fence)
* caught trying to reuse dead objects.
*/
i915_sw_fence_fini(&req->submit);
- i915_sw_fence_fini(&req->execute);

kmem_cache_free(req->i915->requests, req);
}
@@ -211,7 +210,6 @@ static void i915_gem_request_retire(struct drm_i915_gem_request *request)

lockdep_assert_held(&request->i915->drm.struct_mutex);
GEM_BUG_ON(!i915_sw_fence_signaled(&request->submit));
- GEM_BUG_ON(!i915_sw_fence_signaled(&request->execute));
GEM_BUG_ON(!i915_gem_request_completed(request));

GEM_BUG_ON(!request->i915->gt.active_requests);
@@ -422,7 +420,7 @@ void __i915_gem_request_submit(struct drm_i915_gem_request *request)
list_move_tail(&request->link, &timeline->requests);
spin_unlock(&request->timeline->lock);

- i915_sw_fence_commit(&request->execute);
+ wake_up_all(&request->execute);
}

void i915_gem_request_submit(struct drm_i915_gem_request *request)
@@ -457,24 +455,6 @@ submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
return NOTIFY_DONE;
}

-static int __i915_sw_fence_call
-execute_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
-{
- struct drm_i915_gem_request *request =
- container_of(fence, typeof(*request), execute);
-
- switch (state) {
- case FENCE_COMPLETE:
- break;
-
- case FENCE_FREE:
- i915_gem_request_put(request);
- break;
- }
-
- return NOTIFY_DONE;
-}
-
/**
* i915_gem_request_alloc - allocate a request structure
*
@@ -567,13 +547,7 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,

/* We bump the ref for the fence chain */
i915_sw_fence_init(&i915_gem_request_get(req)->submit, submit_notify);
- i915_sw_fence_init(&i915_gem_request_get(req)->execute, execute_notify);
-
- /* Ensure that the execute fence completes after the submit fence -
- * as we complete the execute fence from within the submit fence
- * callback, its completion would otherwise be visible first.
- */
- i915_sw_fence_await_sw_fence(&req->execute, &req->submit, &req->execq);
+ init_waitqueue_head(&req->execute);

i915_priotree_init(&req->priotree);

@@ -1015,6 +989,7 @@ long i915_wait_request(struct drm_i915_gem_request *req,
TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
wait_queue_head_t *errq = &req->i915->gpu_error.wait_queue;
DEFINE_WAIT(reset);
+ DEFINE_WAIT(exec);
struct intel_wait wait;

might_sleep();
@@ -1036,12 +1011,11 @@ long i915_wait_request(struct drm_i915_gem_request *req,
if (flags & I915_WAIT_LOCKED)
add_wait_queue(errq, &reset);

- if (!i915_sw_fence_done(&req->execute)) {
- DEFINE_WAIT(exec);
-
+ reset_wait_queue(&req->execute, &exec);
+ if (!req->global_seqno) {
do {
- prepare_to_wait(&req->execute.wait, &exec, state);
- if (i915_sw_fence_done(&req->execute))
+ set_current_state(state);
+ if (req->global_seqno)
break;

if (flags & I915_WAIT_LOCKED &&
@@ -1064,15 +1038,14 @@ long i915_wait_request(struct drm_i915_gem_request *req,

timeout = io_schedule_timeout(timeout);
} while (1);
- finish_wait(&req->execute.wait, &exec);
+ finish_wait(&req->execute, &exec);

if (timeout < 0)
goto complete;

- GEM_BUG_ON(!i915_sw_fence_done(&req->execute));
+ GEM_BUG_ON(!req->global_seqno);
}
- GEM_BUG_ON(!i915_sw_fence_done(&req->submit));
- GEM_BUG_ON(!req->global_seqno);
+ GEM_BUG_ON(!i915_sw_fence_signaled(&req->submit));

/* Optimistic short spin before touching IRQs */
if (i915_spin_request(req, state, 5))
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index 9049936c571c..467d3e13fce0 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -119,18 +119,10 @@ struct drm_i915_gem_request {
* The submit fence is used to await upon all of the request's
* dependencies. When it is signaled, the request is ready to run.
* It is used by the driver to then queue the request for execution.
- *
- * The execute fence is used to signal when the request has been
- * sent to hardware.
- *
- * It is illegal for the submit fence of one request to wait upon the
- * execute fence of an earlier request. It should be sufficient to
- * wait upon the submit fence of the earlier request.
*/
struct i915_sw_fence submit;
- struct i915_sw_fence execute;
wait_queue_t submitq;
- wait_queue_t execq;
+ wait_queue_head_t execute;

/* A list of everyone we wait upon, and everyone who waits upon us.
* Even though we will not be submitted to the hardware before the
--
2.11.0