drm/i915/gem: Take local vma references for the parser

Take and hold a reference to each of the vma (and their objects) as we
process them with the cmdparser. This stops them being freed during the
work if the GEM execbuf is interrupted and the request we expected to
keep the objects alive is incomplete.

Fixes: 686c7c35 ("drm/i915/gem: Asynchronous cmdparser")
Closes: https://gitlab.freedesktop.org/drm/intel/issues/970Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200113154555.1909639-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -1981,9 +1981,20 @@ static int __eb_parse(struct dma_fence_work *work)
 				       pw->trampoline);
 }
 
+static void __eb_parse_release(struct dma_fence_work *work)
+{
+	struct eb_parse_work *pw = container_of(work, typeof(*pw), base);
+
+	if (pw->trampoline)
+		i915_active_release(&pw->trampoline->active);
+	i915_active_release(&pw->shadow->active);
+	i915_active_release(&pw->batch->active);
+}
+
 static const struct dma_fence_work_ops eb_parse_ops = {
 	.name = "eb_parse",
 	.work = __eb_parse,
+	.release = __eb_parse_release,
 };
 
 static int eb_parse_pipeline(struct i915_execbuffer *eb,
@@ -1997,6 +2008,20 @@ static int eb_parse_pipeline(struct i915_execbuffer *eb,
 	if (!pw)
 		return -ENOMEM;
 
+	err = i915_active_acquire(&eb->batch->active);
+	if (err)
+		goto err_free;
+
+	err = i915_active_acquire(&shadow->active);
+	if (err)
+		goto err_batch;
+
+	if (trampoline) {
+		err = i915_active_acquire(&trampoline->active);
+		if (err)
+			goto err_shadow;
+	}
+
 	dma_fence_work_init(&pw->base, &eb_parse_ops);
 
 	pw->engine = eb->engine;
@@ -2006,7 +2031,9 @@ static int eb_parse_pipeline(struct i915_execbuffer *eb,
 	pw->shadow = shadow;
 	pw->trampoline = trampoline;
 
-	dma_resv_lock(pw->batch->resv, NULL);
+	err = dma_resv_lock_interruptible(pw->batch->resv, NULL);
+	if (err)
+		goto err_trampoline;
 
 	err = dma_resv_reserve_shared(pw->batch->resv, 1);
 	if (err)
@@ -2034,6 +2061,14 @@ static int eb_parse_pipeline(struct i915_execbuffer *eb,
 
 err_batch_unlock:
 	dma_resv_unlock(pw->batch->resv);
+err_trampoline:
+	if (trampoline)
+		i915_active_release(&trampoline->active);
+err_shadow:
+	i915_active_release(&shadow->active);
+err_batch:
+	i915_active_release(&eb->batch->active);
+err_free:
 	kfree(pw);
 	return err;
 }