drm/i915/selftests: Wrap a timer into a i915_sw_fence

For some selftests, we want to issue requests but delay them going to
hardware. Furthermore, we don't want those requests to block
indefinitely (or else we may hang the driver and block testing) so we
want to employ a timeout. So naturally we want a fence that is
automatically signaled by a timer.

v2: Add kselftests.
v3: Limit the API available to selftests; there isn't an overwhelming
reason to export it universally.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171012125726.14736-2-chris@chris-wilson.co.ukReviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/i915_sw_fence.c

@@ -41,6 +41,11 @@ static inline void debug_fence_init(struct i915_sw_fence *fence)
 	debug_object_init(fence, &i915_sw_fence_debug_descr);
 }
 
+static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
+{
+	debug_object_init_on_stack(fence, &i915_sw_fence_debug_descr);
+}
+
 static inline void debug_fence_activate(struct i915_sw_fence *fence)
 {
 	debug_object_activate(fence, &i915_sw_fence_debug_descr);
@@ -79,6 +84,10 @@ static inline void debug_fence_init(struct i915_sw_fence *fence)
 {
 }
 
+static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
+{
+}
+
 static inline void debug_fence_activate(struct i915_sw_fence *fence)
 {
 }
@@ -507,5 +516,6 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/lib_sw_fence.c"
 #include "selftests/i915_sw_fence.c"
 #endif

drivers/gpu/drm/i915/selftests/i915_sw_fence.c

@@ -24,6 +24,7 @@
 
 #include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/prime_numbers.h>
 
 #include "../i915_selftest.h"
 
@@ -565,6 +566,46 @@ static int test_ipc(void *arg)
 	return ret;
 }
 
+static int test_timer(void *arg)
+{
+	unsigned long target, delay;
+	struct timed_fence tf;
+
+	timed_fence_init(&tf, target = jiffies);
+	if (!i915_sw_fence_done(&tf.fence)) {
+		pr_err("Fence with immediate expiration not signaled\n");
+		goto err;
+	}
+	timed_fence_fini(&tf);
+
+	for_each_prime_number(delay, i915_selftest.timeout_jiffies/2) {
+		timed_fence_init(&tf, target = jiffies + delay);
+		if (i915_sw_fence_done(&tf.fence)) {
+			pr_err("Fence with future expiration (%lu jiffies) already signaled\n", delay);
+			goto err;
+		}
+
+		i915_sw_fence_wait(&tf.fence);
+		if (!i915_sw_fence_done(&tf.fence)) {
+			pr_err("Fence not signaled after wait\n");
+			goto err;
+		}
+		if (time_before(jiffies, target)) {
+			pr_err("Fence signaled too early, target=%lu, now=%lu\n",
+			       target, jiffies);
+			goto err;
+		}
+
+		timed_fence_fini(&tf);
+	}
+
+	return 0;
+
+err:
+	timed_fence_fini(&tf);
+	return -EINVAL;
+}
+
 int i915_sw_fence_mock_selftests(void)
 {
 	static const struct i915_subtest tests[] = {
@@ -576,6 +617,7 @@ int i915_sw_fence_mock_selftests(void)
 		SUBTEST(test_C_AB),
 		SUBTEST(test_chain),
 		SUBTEST(test_ipc),
+		SUBTEST(test_timer),
 	};
 
 	return i915_subtests(tests, NULL);

drivers/gpu/drm/i915/selftests/lib_sw_fence.c

+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include "lib_sw_fence.h"
+
+/* Small library of different fence types useful for writing tests */
+
+static int __i915_sw_fence_call
+nop_fence_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
+{
+	return NOTIFY_DONE;
+}
+
+void __onstack_fence_init(struct i915_sw_fence *fence,
+			  const char *name,
+			  struct lock_class_key *key)
+{
+	debug_fence_init_onstack(fence);
+
+	__init_waitqueue_head(&fence->wait, name, key);
+	atomic_set(&fence->pending, 1);
+	fence->flags = (unsigned long)nop_fence_notify;
+}
+
+void onstack_fence_fini(struct i915_sw_fence *fence)
+{
+	i915_sw_fence_commit(fence);
+	i915_sw_fence_fini(fence);
+}
+
+static void timed_fence_wake(unsigned long data)
+{
+	struct timed_fence *tf = (struct timed_fence *)data;
+
+	i915_sw_fence_commit(&tf->fence);
+}
+
+void timed_fence_init(struct timed_fence *tf, unsigned long expires)
+{
+	onstack_fence_init(&tf->fence);
+
+	setup_timer_on_stack(&tf->timer, timed_fence_wake, (unsigned long)tf);
+
+	if (time_after(expires, jiffies))
+		mod_timer(&tf->timer, expires);
+	else
+		i915_sw_fence_commit(&tf->fence);
+}
+
+void timed_fence_fini(struct timed_fence *tf)
+{
+	if (del_timer_sync(&tf->timer))
+		i915_sw_fence_commit(&tf->fence);
+
+	destroy_timer_on_stack(&tf->timer);
+	i915_sw_fence_fini(&tf->fence);
+}

drivers/gpu/drm/i915/selftests/lib_sw_fence.h

+/*
+ * lib_sw_fence.h - library routines for testing N:M synchronisation points
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#ifndef _LIB_SW_FENCE_H_
+#define _LIB_SW_FENCE_H_
+
+#include <linux/timer.h>
+
+#include "../i915_sw_fence.h"
+
+#ifdef CONFIG_LOCKDEP
+#define onstack_fence_init(fence)				\
+do {								\
+	static struct lock_class_key __key;			\
+								\
+	__onstack_fence_init((fence), #fence, &__key);	\
+} while (0)
+#else
+#define onstack_fence_init(fence)				\
+	__onstack_fence_init((fence), NULL, NULL)
+#endif
+
+void __onstack_fence_init(struct i915_sw_fence *fence,
+			  const char *name,
+			  struct lock_class_key *key);
+void onstack_fence_fini(struct i915_sw_fence *fence);
+
+struct timed_fence {
+	struct i915_sw_fence fence;
+	struct timer_list timer;
+};
+
+void timed_fence_init(struct timed_fence *tf, unsigned long expires);
+void timed_fence_fini(struct timed_fence *tf);
+
+#endif /* _LIB_SW_FENCE_H_ */