Re: [PATCH] drm/xe/hw_engine_group: Fix bad free in xe_hw_engine_setup_groups()

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On 2024/11/14 15:45, Vivekanandan, Balasubramani wrote:
On 14.11.2024 14:39, Su Hui wrote:

diff --git a/drivers/gpu/drm/xe/xe_hw_engine_group.c b/drivers/gpu/drm/xe/xe_hw_engine_group.c
index 82750520a90a..ee2cb32817fa 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine_group.c
+++ b/drivers/gpu/drm/xe/xe_hw_engine_group.c
@@ -51,7 +51,7 @@ static struct xe_hw_engine_group *
  hw_engine_group_alloc(struct xe_device *xe)
  {
  	struct xe_hw_engine_group *group;
-	int err;
+	int err = -ENOMEM;
group = kzalloc(sizeof(*group), GFP_KERNEL);
  	if (!group)
@@ -59,7 +59,7 @@ hw_engine_group_alloc(struct xe_device *xe)
group->resume_wq = alloc_workqueue("xe-resume-lr-jobs-wq", 0, 0);
  	if (!group->resume_wq)
-		return ERR_PTR(-ENOMEM);
+		goto free_group;
kfree can be directly called from here followed by return, instead of a
goto.
Agreed.
init_rwsem(&group->mode_sem);
  	INIT_WORK(&group->resume_work, hw_engine_group_resume_lr_jobs_func);
@@ -67,9 +67,15 @@ hw_engine_group_alloc(struct xe_device *xe)
err = drmm_add_action_or_reset(&xe->drm, hw_engine_group_free, group);
  	if (err)
-		return ERR_PTR(err);
+		goto destroy_wq;
There is no need to clear the resources on failure, because
drmm_add_action_or_reset takes care of freeing the resources on
failure.
Oh, my fault, I missed this function.
/**
@@ -87,21 +93,19 @@ int xe_hw_engine_setup_groups(struct xe_gt *gt)
  	int err;
group_rcs_ccs = hw_engine_group_alloc(xe);
-	if (IS_ERR(group_rcs_ccs)) {
-		err = PTR_ERR(group_rcs_ccs);
-		goto err_group_rcs_ccs;
-	}
+	if (IS_ERR(group_rcs_ccs))
+		return PTR_ERR(group_rcs_ccs);
group_bcs = hw_engine_group_alloc(xe);
  	if (IS_ERR(group_bcs)) {
  		err = PTR_ERR(group_bcs);
-		goto err_group_bcs;
+		goto free_group_rcs_ccs;
No need of freeing the memory here and in the following lines as we have
managed it through the drmm_add_action_or_reset call in
hw_engine_group_alloc.
We can simply return the error code.
Got it.

-err_group_vcs_vecs:
-	kfree(group_vcs_vecs);
-err_group_bcs:
+free_group_bcs:
+	destroy_workqueue(group_bcs->resume_wq);
  	kfree(group_bcs);
-err_group_rcs_ccs:
+free_group_rcs_ccs:
+	destroy_workqueue(group_rcs_ccs->resume_wq);
  	kfree(group_rcs_ccs);
-
All these kfree statements are not required.
Agreed too. Thanks for your review.
I will send a v2 patch to remove these kfree if there are no further suggestions.

Regards,
Su Hui






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