[PATCH v2 21/23] drm/xe: forcewake debugfs open fails on xe_forcewake_get failure

[Himal Prasad Ghimiray]

A failure in xe_force_wake_get() no longer increments the domain's
refcount. Therefore, if xe_force_wake_get() fails during forcewake
debugfs open, return an error. This ensures there are no valid file
descriptors to close via forcewake debugfs, preventing refcount
mismanagement.

Cc: Badal Nilawar <badal.nilawar at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
---
 drivers/gpu/drm/xe/xe_debugfs.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
index a64bae36e0e3..acee79a1305f 100644
--- a/drivers/gpu/drm/xe/xe_debugfs.c
+++ b/drivers/gpu/drm/xe/xe_debugfs.c
@@ -92,13 +92,34 @@ static int forcewake_open(struct inode *inode, struct file *file)
 {
 	struct xe_device *xe = inode->i_private;
 	struct xe_gt *gt;
-	u8 id;
+	u8 id, last_gt;
+	int  fw_ref;
 
 	xe_pm_runtime_get(xe);
-	for_each_gt(gt, xe, id)
-		XE_WARN_ON(xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL));
+	for_each_gt(gt, xe, id) {
+		last_gt = id;
+
+		fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
+		if (fw_ref != XE_FORCEWAKE_ALL) {
+			xe_gt_WARN_ON(gt, true);
+			goto err_fw_get;
+		}
+	}
 
 	return 0;
+
+err_fw_get:
+	for_each_gt(gt, xe, id) {
+		if (id < last_gt)
+			xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL);
+		else if (id == last_gt)
+			xe_force_wake_put(gt_to_fw(gt), fw_ref);
+		else
+			break;
+	}
+
+	xe_pm_runtime_put(xe);
+	return -ETIMEDOUT;
 }
 
 static int forcewake_release(struct inode *inode, struct file *file)
@@ -108,7 +129,7 @@ static int forcewake_release(struct inode *inode, struct file *file)
 	u8 id;
 
 	for_each_gt(gt, xe, id)
-		XE_WARN_ON(xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL));
+		xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL);
 	xe_pm_runtime_put(xe);
 
 	return 0;
-- 
2.34.1