drm/i915: Allow asynchronous waits on the i915_active barriers

Allow the caller to also wait upon the barriers stored in i915_active.

v2: Hook up i915_request_await_active(I915_ACTIVE_AWAIT_BARRIER) as well
for completeness, and avoid the lazy GEM_BUG_ON()!

v3: Pull flush_lazy_signals() under the active-ref protection as it too
walks the rbtree and so we must be careful that we do not free it as we
iterate.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200406155840.1728-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index d5e24be..d960d0b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -542,35 +542,88 @@ static int __await_active(struct i915_active_fence *active,
        return 0;
 }
 
+struct wait_barrier {
+       struct wait_queue_entry base;
+       struct i915_active *ref;
+};
+
+static int
+barrier_wake(wait_queue_entry_t *wq, unsigned int mode, int flags, void *key)
+{
+       struct wait_barrier *wb = container_of(wq, typeof(*wb), base);
+
+       if (i915_active_is_idle(wb->ref)) {
+               list_del(&wq->entry);
+               i915_sw_fence_complete(wq->private);
+               kfree(wq);
+       }
+
+       return 0;
+}
+
+static int __await_barrier(struct i915_active *ref, struct i915_sw_fence *fence)
+{
+       struct wait_barrier *wb;
+
+       wb = kmalloc(sizeof(*wb), GFP_KERNEL);
+       if (unlikely(!wb))
+               return -ENOMEM;
+
+       GEM_BUG_ON(i915_active_is_idle(ref));
+       if (!i915_sw_fence_await(fence)) {
+               kfree(wb);
+               return -EINVAL;
+       }
+
+       wb->base.flags = 0;
+       wb->base.func = barrier_wake;
+       wb->base.private = fence;
+       wb->ref = ref;
+
+       add_wait_queue(__var_waitqueue(ref), &wb->base);
+       return 0;
+}
+
 static int await_active(struct i915_active *ref,
                        unsigned int flags,
                        int (*fn)(void *arg, struct dma_fence *fence),
-                       void *arg)
+                       void *arg, struct i915_sw_fence *barrier)
 {
        int err = 0;
 
+       if (!i915_active_acquire_if_busy(ref))
+               return 0;
+
        if (flags & I915_ACTIVE_AWAIT_EXCL &&
            rcu_access_pointer(ref->excl.fence)) {
                err = __await_active(&ref->excl, fn, arg);
                if (err)
-                       return err;
+                       goto out;
        }
 
-       if (flags & I915_ACTIVE_AWAIT_ACTIVE &&
-           i915_active_acquire_if_busy(ref)) {
+       if (flags & I915_ACTIVE_AWAIT_ACTIVE) {
                struct active_node *it, *n;
 
                rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
                        err = __await_active(&it->base, fn, arg);
                        if (err)
-                               break;
+                               goto out;
                }
-               i915_active_release(ref);
+       }
+
+       if (flags & I915_ACTIVE_AWAIT_BARRIER) {
+               err = flush_lazy_signals(ref);
                if (err)
-                       return err;
+                       goto out;
+
+               err = __await_barrier(ref, barrier);
+               if (err)
+                       goto out;
        }
 
-       return 0;
+out:
+       i915_active_release(ref);
+       return err;
 }
 
 static int rq_await_fence(void *arg, struct dma_fence *fence)
@@ -582,7 +635,7 @@ int i915_request_await_active(struct i915_request *rq,
                              struct i915_active *ref,
                              unsigned int flags)
 {
-       return await_active(ref, flags, rq_await_fence, rq);
+       return await_active(ref, flags, rq_await_fence, rq, &rq->submit);
 }
 
 static int sw_await_fence(void *arg, struct dma_fence *fence)
@@ -595,7 +648,7 @@ int i915_sw_fence_await_active(struct i915_sw_fence *fence,
                               struct i915_active *ref,
                               unsigned int flags)
 {
-       return await_active(ref, flags, sw_await_fence, fence);
+       return await_active(ref, flags, sw_await_fence, fence, fence);
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)

diff --git a/drivers/gpu/drm/i915/i915_active.h b/drivers/gpu/drm/i915/i915_active.h
index ffafaa7..cf40581 100644 (file)
--- a/drivers/gpu/drm/i915/i915_active.h
+++ b/drivers/gpu/drm/i915/i915_active.h
@@ -195,6 +195,7 @@ int i915_request_await_active(struct i915_request *rq,
                              unsigned int flags);
 #define I915_ACTIVE_AWAIT_EXCL BIT(0)
 #define I915_ACTIVE_AWAIT_ACTIVE BIT(1)
+#define I915_ACTIVE_AWAIT_BARRIER BIT(2)
 
 int i915_active_acquire(struct i915_active *ref);
 bool i915_active_acquire_if_busy(struct i915_active *ref);