[Intel-xe] [PATCH] drm/xe: Don't grab runtime PM ref in engine create IOCTL

[Matthew Brost]

A VM had a runtime PM ref, a engine can't be created without a VM, and
the engine holds a ref to the VM thus this is unnecessary. Beyond that
taking a ref in the engine create IOCTL and dropping it in the destroy
IOCTL is wrong as a user doesn't have to call the destroy IOCTL (e.g.
they can just kill the process or close the driver FD). If a user does
this PM refs are leaked.

Signed-off-by: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/xe/xe_engine.c | 43 ++++++++++------------------------
 1 file changed, 13 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_engine.c b/drivers/gpu/drm/xe/xe_engine.c
index 37209b13bcd6..094ec17d3004 100644
--- a/drivers/gpu/drm/xe/xe_engine.c
+++ b/drivers/gpu/drm/xe/xe_engine.c
@@ -539,8 +539,6 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
 	if (XE_IOCTL_ERR(xe, eci[0].gt_id >= xe->info.tile_count))
 	       return -EINVAL;
 
-	xe_pm_runtime_get(xe);
-
 	if (eci[0].engine_class == DRM_XE_ENGINE_CLASS_VM_BIND) {
 		for_each_gt(gt, xe, id) {
 			struct xe_engine *new;
@@ -552,16 +550,12 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
 			logical_mask = bind_engine_logical_mask(xe, gt, eci,
 								args->width,
 								args->num_placements);
-			if (XE_IOCTL_ERR(xe, !logical_mask)) {
-				err = -EINVAL;
-				goto put_rpm;
-			}
+			if (XE_IOCTL_ERR(xe, !logical_mask))
+				return -EINVAL;
 
 			hwe = find_hw_engine(xe, eci[0]);
-			if (XE_IOCTL_ERR(xe, !hwe)) {
-				err = -EINVAL;
-				goto put_rpm;
-			}
+			if (XE_IOCTL_ERR(xe, !hwe))
+				return -EINVAL;
 
 			migrate_vm = xe_migrate_get_vm(gt->migrate);
 			new = xe_engine_create(xe, migrate_vm, logical_mask,
@@ -576,7 +570,7 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
 				err = PTR_ERR(new);
 				if (e)
 					goto put_engine;
-				goto put_rpm;
+				return err;
 			}
 			if (id == 0)
 				e = new;
@@ -589,30 +583,22 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
 		logical_mask = calc_validate_logical_mask(xe, gt, eci,
 							  args->width,
 							  args->num_placements);
-		if (XE_IOCTL_ERR(xe, !logical_mask)) {
-			err = -EINVAL;
-			goto put_rpm;
-		}
+		if (XE_IOCTL_ERR(xe, !logical_mask))
+			return -EINVAL;
 
 		hwe = find_hw_engine(xe, eci[0]);
-		if (XE_IOCTL_ERR(xe, !hwe)) {
-			err = -EINVAL;
-			goto put_rpm;
-		}
+		if (XE_IOCTL_ERR(xe, !hwe))
+			return -EINVAL;
 
 		vm = xe_vm_lookup(xef, args->vm_id);
-		if (XE_IOCTL_ERR(xe, !vm)) {
-			err = -ENOENT;
-			goto put_rpm;
-		}
+		if (XE_IOCTL_ERR(xe, !vm))
+			return -ENOENT;
 
 		e = xe_engine_create(xe, vm, logical_mask,
 				     args->width, hwe, ENGINE_FLAG_PERSISTENT);
 		xe_vm_put(vm);
-		if (IS_ERR(e)) {
-			err = PTR_ERR(e);
-			goto put_rpm;
-		}
+		if (IS_ERR(e))
+			return PTR_ERR(e);
 	}
 
 	if (args->extensions) {
@@ -642,8 +628,6 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
 put_engine:
 	xe_engine_kill(e);
 	xe_engine_put(e);
-put_rpm:
-	xe_pm_runtime_put(xe);
 	return err;
 }
 
@@ -750,7 +734,6 @@ int xe_engine_destroy_ioctl(struct drm_device *dev, void *data,
 
 	trace_xe_engine_close(e);
 	xe_engine_put(e);
-	xe_pm_runtime_put(xe);
 
 	return 0;
 }
-- 
2.34.1