Third retroactive test, make sure that the seqno waiters are woken.
v2: Smattering of comments, rearrange code
v3: Fix IDLE assert to avoid startup/sleep races
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c | 201 +++++++++++++++++++++
1 file changed, 201 insertions(+)
diff --git a/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c b/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c
index 32a27e56c353..d1b99b565500 100644
--- a/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c
@@ -259,11 +259,212 @@ static int igt_insert_complete(void *arg)
return err;
}
+struct igt_wakeup {
+ struct task_struct *tsk;
+ atomic_t *ready, *set, *done;
+ struct intel_engine_cs *engine;
+ unsigned long flags;
+#define STOP 0
+#define IDLE 1
+ wait_queue_head_t *wq;
+ u32 seqno;
+};
+
+static int wait_atomic(atomic_t *p)
+{
+ schedule();
+ return 0;
+}
+
+static int wait_atomic_timeout(atomic_t *p)
+{
+ return schedule_timeout(10 * HZ) ? 0 : -ETIMEDOUT;
+}
+
+static bool wait_for_ready(struct igt_wakeup *w)
+{
+ DEFINE_WAIT(ready);
+
+ set_bit(IDLE, &w->flags);
+ if (atomic_dec_and_test(w->done))
+ wake_up_atomic_t(w->done);
+
+ if (test_bit(STOP, &w->flags))
+ goto out;
+
+ for (;;) {
+ prepare_to_wait(w->wq, &ready, TASK_INTERRUPTIBLE);
+ if (atomic_read(w->ready) == 0)
+ break;
+
+ schedule();
+ }
+ finish_wait(w->wq, &ready);
+
+out:
+ clear_bit(IDLE, &w->flags);
+ if (atomic_dec_and_test(w->set))
+ wake_up_atomic_t(w->set);
+
+ return !test_bit(STOP, &w->flags);
+}
+
+static int igt_wakeup_thread(void *arg)
+{
+ struct igt_wakeup *w = arg;
+ struct intel_wait wait;
+
+ while (wait_for_ready(w)) {
+ GEM_BUG_ON(kthread_should_stop());
+
+ intel_wait_init(&wait, w->seqno);
+ intel_engine_add_wait(w->engine, &wait);
+ for (;;) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (i915_seqno_passed(intel_engine_get_seqno(w->engine),
+ w->seqno))
+ break;
+
+ if (test_bit(STOP, &w->flags)) /* emergency escape */
+ break;
+
+ schedule();
+ }
+ intel_engine_remove_wait(w->engine, &wait);
+ __set_current_state(TASK_RUNNING);
+ }
+
+ return 0;
+}
+
+static void igt_wake_all_sync(atomic_t *ready,
+ atomic_t *set,
+ atomic_t *done,
+ wait_queue_head_t *wq,
+ int count)
+{
+ atomic_set(set, count);
+ atomic_set(ready, 0);
+ wake_up_all(wq);
+
+ wait_on_atomic_t(set, wait_atomic, TASK_UNINTERRUPTIBLE);
+ atomic_set(ready, count);
+ atomic_set(done, count);
+}
+
+static int igt_wakeup(void *arg)
+{
+ I915_RND_STATE(prng);
+ const int state = TASK_UNINTERRUPTIBLE;
+ struct intel_engine_cs *engine = arg;
+ struct igt_wakeup *waiters;
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+ const int count = 4096;
+ const u32 max_seqno = count / 4;
+ atomic_t ready, set, done;
+ int err = -ENOMEM;
+ int n, step;
+
+ mock_engine_reset(engine);
+
+ waiters = drm_malloc_gfp(count, sizeof(*waiters), GFP_TEMPORARY);
+ if (!waiters)
+ goto out_engines;
+
+ /* Create a large number of threads, each waiting on a random seqno.
+ * Multiple waiters will be waiting for the same seqno.
+ */
+ atomic_set(&ready, count);
+ for (n = 0; n < count; n++) {
+ waiters[n].wq = &wq;
+ waiters[n].ready = &ready;
+ waiters[n].set = &set;
+ waiters[n].done = &done;
+ waiters[n].engine = engine;
+ waiters[n].flags = BIT(IDLE);
+
+ waiters[n].tsk = kthread_run(igt_wakeup_thread, &waiters[n],
+ "i915/igt:%d", n);
+ if (IS_ERR(waiters[n].tsk))
+ goto out_waiters;
+
+ get_task_struct(waiters[n].tsk);
+ }
+
+ for (step = 1; step <= max_seqno; step <<= 1) {
+ u32 seqno;
+
+ /* The waiter threads start paused as we assign them a random
+ * seqno and reset the engine. Once the engine is reset,
+ * we signal that the threads may begin their wait upon their
+ * seqno.
+ */
+ for (n = 0; n < count; n++) {
+ GEM_BUG_ON(!test_bit(IDLE, &waiters[n].flags));
+ waiters[n].seqno =
+ 1 + prandom_u32_state(&prng) % max_seqno;
+ }
+ mock_seqno_advance(engine, 0);
+ igt_wake_all_sync(&ready, &set, &done, &wq, count);
+
+ /* Simulate the GPU doing chunks of work, with one or more
+ * seqno appearing to finish at the same time. A random number
+ * of threads will be waiting upon the update and hopefully be
+ * woken.
+ */
+ for (seqno = 1; seqno <= max_seqno + step; seqno += step) {
+ usleep_range(50, 500);
+ mock_seqno_advance(engine, seqno);
+ }
+ GEM_BUG_ON(intel_engine_get_seqno(engine) < 1 + max_seqno);
+
+ /* With the seqno now beyond any of the waiting threads, they
+ * should all be woken, see that they are complete and signal
+ * that they are ready for the next test. We wait until all
+ * threads are complete and waiting for us (i.e. not a seqno).
+ */
+ err = wait_on_atomic_t(&done, wait_atomic_timeout, state);
+ if (err) {
+ pr_err("Timed out waiting for %d remaining waiters\n",
+ atomic_read(&done));
+ break;
+ }
+
+ err = check_rbtree_empty(engine);
+ if (err)
+ break;
+ }
+
+out_waiters:
+ for (n = 0; n < count; n++) {
+ if (IS_ERR(waiters[n].tsk))
+ break;
+
+ set_bit(STOP, &waiters[n].flags);
+ }
+ mock_seqno_advance(engine, INT_MAX); /* wakeup any broken waiters */
+ igt_wake_all_sync(&ready, &set, &done, &wq, n);
+
+ for (n = 0; n < count; n++) {
+ if (IS_ERR(waiters[n].tsk))
+ break;
+
+ kthread_stop(waiters[n].tsk);
+ put_task_struct(waiters[n].tsk);
+ }
+
+ drm_free_large(waiters);
+out_engines:
+ mock_engine_flush(engine);
+ return err;
+}
+
int intel_breadcrumbs_mock_selftests(void)
{
static const struct i915_subtest tests[] = {
SUBTEST(igt_random_insert_remove),
SUBTEST(igt_insert_complete),
+ SUBTEST(igt_wakeup),
};
struct intel_engine_cs *engine;
int err;
--
2.11.0
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