From 6ab707e575fefa32c039ce5f815e4859b6cd1d47 Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sat, 31 Dec 2022 12:56:49 +0100
Subject: mach-defpager: document lock ordering

---
 mach-defpager/priv.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'mach-defpager')

diff --git a/mach-defpager/priv.h b/mach-defpager/priv.h
index 6f5aade6..d77e509c 100644
--- a/mach-defpager/priv.h
+++ b/mach-defpager/priv.h
@@ -31,6 +31,28 @@
 #include <queue.h>
 #include <hurd/ihash.h>
 
+/*
+ * Note: lock ordering:
+ *
+ * - all_partitions.lock
+ * - part->p_lock
+ *
+ * (from S_default_pager_objects)
+ * - all_pagers.lock
+ * - dstruct_lock
+ *
+ * (from S_default_pager_object_set_size that calls pager_truncate)
+ * - dstruct_lock
+ * - pager.lock
+ * - part->p_lock
+ *
+ * (from destroy_paging_partition)
+ * - all_partitions.lock
+ * - part->p_lock
+ * - all_pagers.lock
+ * - dstruct_lock
+ */
+
 /*
  * Bitmap allocation.
  */
-- 
cgit v1.2.3