[PATCH 2/2] drm/xe: Record utilization before destroying the exec queue

[Umesh Nerlige Ramappa]

Current code captures utilization at the exec queue level whenever a job
is completed and then accumulates it into the xe file stats whenever the
user queries for per client engine utilization. There is a case where
utilization may be lost if the exec queue is destroyed before the user
queries the utilization. To overcome that, record the utlization when
the exec queue is destroyed.

To do so

1) Wait for release of all other references to the exec queue. The wait
   uses the same timeout as the job scheduling timeout. On timeout, only
   a debug message is printed out since this is just a best effort to
   capture the utilization prior to destroying the queue.
2) Before releasing the last reference in xe_exec_queue_destroy_ioctl(),
   record the utilization in the xe file stats.

Fixes: ce62827bc294 ("drm/xe: Do not access xe file when updating exec queue run_ticks")
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
---
 drivers/gpu/drm/xe/xe_exec_queue.c       | 11 +++++++++++
 drivers/gpu/drm/xe/xe_exec_queue_types.h |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
index 4d90a16745d2..f1028eaf2d7f 100644
--- a/drivers/gpu/drm/xe/xe_exec_queue.c
+++ b/drivers/gpu/drm/xe/xe_exec_queue.c
@@ -69,6 +69,7 @@ static struct xe_exec_queue *__xe_exec_queue_alloc(struct xe_device *xe,
 	q->ops = gt->exec_queue_ops;
 	INIT_LIST_HEAD(&q->lr.link);
 	INIT_LIST_HEAD(&q->multi_gt_link);
+	init_waitqueue_head(&q->wq);
 
 	q->sched_props.timeslice_us = hwe->eclass->sched_props.timeslice_us;
 	q->sched_props.preempt_timeout_us =
@@ -825,6 +826,7 @@ int xe_exec_queue_destroy_ioctl(struct drm_device *dev, void *data,
 	struct xe_file *xef = to_xe_file(file);
 	struct drm_xe_exec_queue_destroy *args = data;
 	struct xe_exec_queue *q;
+	int ret;
 
 	if (XE_IOCTL_DBG(xe, args->pad) ||
 	    XE_IOCTL_DBG(xe, args->reserved[0] || args->reserved[1]))
@@ -838,6 +840,15 @@ int xe_exec_queue_destroy_ioctl(struct drm_device *dev, void *data,
 
 	xe_exec_queue_kill(q);
 
+	ret = wait_event_timeout(q->wq, kref_read(&q->refcount) == 1,
+			(q->sched_props.job_timeout_ms/1000) * HZ);
+	if (!ret)
+		drm_dbg(&xe->drm, "Timedout waiting for exec queue run ticks update\n");
+
+	mutex_lock(&xef->exec_queue.lock);
+	xef->run_ticks[q->class] += xe_exec_queue_delta_run_ticks(q);
+	mutex_unlock(&xef->exec_queue.lock);
+
 	trace_xe_exec_queue_close(q);
 	xe_exec_queue_put(q);
 
diff --git a/drivers/gpu/drm/xe/xe_exec_queue_types.h b/drivers/gpu/drm/xe/xe_exec_queue_types.h
index 201588ec33c3..2ae4221d2f61 100644
--- a/drivers/gpu/drm/xe/xe_exec_queue_types.h
+++ b/drivers/gpu/drm/xe/xe_exec_queue_types.h
@@ -143,6 +143,8 @@ struct xe_exec_queue {
 	u64 old_run_ticks;
 	/** @run_ticks: hw engine class run time in ticks for this exec queue */
 	u64 run_ticks;
+	/** @wq: wait queue to wait for cleanup */
+	wait_queue_head_t wq;
 	/** @lrc: logical ring context for this exec queue */
 	struct xe_lrc *lrc[];
 };
-- 
2.34.1