[RFC PATCH 25/29] drm/xe: Add a message lock to the Xe GPU scheduler

[Matthew Brost]

Stop abusing job list lock for message, use a dedicated lock. This lock
will soon be able to be taken in IRQ contexts, using irqsave for
simplicity. Can to tweaked in a follow up as needed.

Signed-off-by: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/xe/xe_gpu_scheduler.c       | 19 ++++++++++++-------
 drivers/gpu/drm/xe/xe_gpu_scheduler.h       | 12 ++++--------
 drivers/gpu/drm/xe/xe_gpu_scheduler_types.h |  2 ++
 drivers/gpu/drm/xe/xe_guc_submit.c          | 15 +++++++++------
 4 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.c b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
index 50361b4638f9..55ccfb587523 100644
--- a/drivers/gpu/drm/xe/xe_gpu_scheduler.c
+++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
@@ -14,25 +14,27 @@ static void xe_sched_process_msg_queue(struct xe_gpu_scheduler *sched)
 static void xe_sched_process_msg_queue_if_ready(struct xe_gpu_scheduler *sched)
 {
 	struct xe_sched_msg *msg;
+	unsigned long flags;
 
-	xe_sched_msg_lock(sched);
+	xe_sched_msg_lock(sched, flags);
 	msg = list_first_entry_or_null(&sched->msgs, struct xe_sched_msg, link);
 	if (msg)
 		xe_sched_process_msg_queue(sched);
-	xe_sched_msg_unlock(sched);
+	xe_sched_msg_unlock(sched, flags);
 }
 
 static struct xe_sched_msg *
 xe_sched_get_msg(struct xe_gpu_scheduler *sched)
 {
 	struct xe_sched_msg *msg;
+	unsigned long flags;
 
-	xe_sched_msg_lock(sched);
+	xe_sched_msg_lock(sched, flags);
 	msg = list_first_entry_or_null(&sched->msgs,
 				       struct xe_sched_msg, link);
 	if (msg)
 		list_del_init(&msg->link);
-	xe_sched_msg_unlock(sched);
+	xe_sched_msg_unlock(sched, flags);
 
 	return msg;
 }
@@ -64,6 +66,7 @@ int xe_sched_init(struct xe_gpu_scheduler *sched,
 		  struct device *dev)
 {
 	sched->ops = xe_ops;
+	spin_lock_init(&sched->msg_lock);
 	INIT_LIST_HEAD(&sched->msgs);
 	INIT_WORK(&sched->work_process_msg, xe_sched_process_msg_work);
 
@@ -98,15 +101,17 @@ void xe_sched_submission_resume_tdr(struct xe_gpu_scheduler *sched)
 void xe_sched_add_msg(struct xe_gpu_scheduler *sched,
 		      struct xe_sched_msg *msg)
 {
-	xe_sched_msg_lock(sched);
+	unsigned long flags;
+
+	xe_sched_msg_lock(sched, flags);
 	xe_sched_add_msg_locked(sched, msg);
-	xe_sched_msg_unlock(sched);
+	xe_sched_msg_unlock(sched, flags);
 }
 
 void xe_sched_add_msg_locked(struct xe_gpu_scheduler *sched,
 			     struct xe_sched_msg *msg)
 {
-	lockdep_assert_held(&sched->base.job_list_lock);
+	lockdep_assert_held(&sched->msg_lock);
 
 	list_add_tail(&msg->link, &sched->msgs);
 	xe_sched_process_msg_queue(sched);
diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.h b/drivers/gpu/drm/xe/xe_gpu_scheduler.h
index c250ea773491..3238de26dcfe 100644
--- a/drivers/gpu/drm/xe/xe_gpu_scheduler.h
+++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.h
@@ -29,15 +29,11 @@ void xe_sched_add_msg(struct xe_gpu_scheduler *sched,
 void xe_sched_add_msg_locked(struct xe_gpu_scheduler *sched,
 			     struct xe_sched_msg *msg);
 
-static inline void xe_sched_msg_lock(struct xe_gpu_scheduler *sched)
-{
-	spin_lock(&sched->base.job_list_lock);
-}
+#define xe_sched_msg_lock(sched, flags) \
+	spin_lock_irqsave(&sched->msg_lock, flags)
 
-static inline void xe_sched_msg_unlock(struct xe_gpu_scheduler *sched)
-{
-	spin_unlock(&sched->base.job_list_lock);
-}
+#define xe_sched_msg_unlock(sched, flags) \
+	spin_unlock_irqrestore(&sched->msg_lock, flags)
 
 static inline void xe_sched_stop(struct xe_gpu_scheduler *sched)
 {
diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h b/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h
index 6731b13da8bb..c8e0352ef941 100644
--- a/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h
+++ b/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h
@@ -47,6 +47,8 @@ struct xe_gpu_scheduler {
 	const struct xe_sched_backend_ops	*ops;
 	/** @msgs: list of messages to be processed in @work_process_msg */
 	struct list_head			msgs;
+	/** @msg_lock: Lock for messages */
+	spinlock_t msg_lock;
 	/** @work_process_msg: processes messages */
 	struct work_struct		work_process_msg;
 };
diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 82071a0ec91e..3efd2000c0a2 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1704,14 +1704,15 @@ static int guc_exec_queue_suspend(struct xe_exec_queue *q)
 {
 	struct xe_gpu_scheduler *sched = &q->guc->sched;
 	struct xe_sched_msg *msg = q->guc->static_msgs + STATIC_MSG_SUSPEND;
+	unsigned long flags;
 
 	if (exec_queue_killed_or_banned_or_wedged(q))
 		return -EINVAL;
 
-	xe_sched_msg_lock(sched);
+	xe_sched_msg_lock(sched, flags);
 	if (guc_exec_queue_try_add_msg(q, msg, SUSPEND))
 		q->guc->suspend_pending = true;
-	xe_sched_msg_unlock(sched);
+	xe_sched_msg_unlock(sched, flags);
 
 	return 0;
 }
@@ -1751,30 +1752,32 @@ static void guc_exec_queue_resume(struct xe_exec_queue *q)
 	struct xe_gpu_scheduler *sched = &q->guc->sched;
 	struct xe_sched_msg *msg = q->guc->static_msgs + STATIC_MSG_RESUME;
 	struct xe_guc *guc = exec_queue_to_guc(q);
+	unsigned long flags;
 
 	xe_gt_assert(guc_to_gt(guc), !q->guc->suspend_pending);
 
-	xe_sched_msg_lock(sched);
+	xe_sched_msg_lock(sched, flags);
 	guc_exec_queue_try_add_msg(q, msg, RESUME);
-	xe_sched_msg_unlock(sched);
+	xe_sched_msg_unlock(sched, flags);
 }
 
 static void guc_exec_queue_kill_user(struct xe_exec_queue *q)
 {
 	struct xe_gpu_scheduler *sched = &q->guc->sched;
 	struct xe_sched_msg *msg = q->guc->static_msgs + STATIC_MSG_KILL_USER;
+	unsigned long flags;
 
 	if (exec_queue_extra_ref(q))
 		return;
 
 	set_exec_queue_banned(q);
 
-	xe_sched_msg_lock(sched);
+	xe_sched_msg_lock(sched, flags);
 	if (guc_exec_queue_try_add_msg(q, msg, KILL_USER)) {
 		set_exec_queue_extra_ref(q);
 		xe_exec_queue_get(q);
 	}
-	xe_sched_msg_unlock(sched);
+	xe_sched_msg_unlock(sched, flags);
 }
 
 static bool guc_exec_queue_reset_status(struct xe_exec_queue *q)
-- 
2.34.1