drm/i915/display: add lock while printing frontbuffer tracking bits to debugfs

Add missing spin_lock/unlock
Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230814163452.2925-1-juhapekka.heikkila@gmail.com

drivers/gpu/drm/i915/display/intel_display_debugfs.c

@@ -43,12 +43,16 @@ static int i915_frontbuffer_tracking(struct seq_file *m, void *unused)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
 
+	spin_lock(&dev_priv->display.fb_tracking.lock);
+
 	seq_printf(m, "FB tracking busy bits: 0x%08x\n",
 		   dev_priv->display.fb_tracking.busy_bits);
 
 	seq_printf(m, "FB tracking flip bits: 0x%08x\n",
 		   dev_priv->display.fb_tracking.flip_bits);
 
+	spin_unlock(&dev_priv->display.fb_tracking.lock);
+
 	return 0;
 }