From 2fbe967b3eb7466f679307b38564b8271c093241 Mon Sep 17 00:00:00 2001
From: Matthew Wilcox <willy@infradead.org>
Date: Thu, 21 Feb 2019 17:36:45 -0500
Subject: [PATCH] XArray: Fix xa_erase of 2-byte aligned entries
xas_store() was interpreting the entry it found in the array as a node
entry if the bottom two bits had value 2. That's only true if either
the entry is in the root node or in a non-leaf node.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
lib/test_xarray.c | 16 +++++++++++++++-
lib/xarray.c | 2 +-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 52f8ecff8c0cc..bc202d468a6b0 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1355,6 +1355,20 @@ static void check_align_1(struct xarray *xa, char *name)
xa_destroy(xa);
}
+static void check_align_2(struct xarray *xa, char *name)
+{
+ int i;
+
+ XA_BUG_ON(xa, !xa_empty(xa));
+
+ for (i = 0; i < 8; i++) {
+ XA_BUG_ON(xa, xa_store(xa, 0, name + i, GFP_KERNEL) != NULL);
+ xa_erase(xa, 0);
+ }
+
+ XA_BUG_ON(xa, !xa_empty(xa));
+}
+
static noinline void check_align(struct xarray *xa)
{
char name[] = "Motorola 68000";
@@ -1363,7 +1377,7 @@ static noinline void check_align(struct xarray *xa)
check_align_1(xa, name + 1);
check_align_1(xa, name + 2);
check_align_1(xa, name + 3);
-// check_align_2(xa, name);
+ check_align_2(xa, name);
}
static LIST_HEAD(shadow_nodes);
diff --git a/lib/xarray.c b/lib/xarray.c
index 3f10198f00b77..2cc3798672f7d 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -800,7 +800,7 @@ void *xas_store(struct xa_state *xas, void *entry)
* entry is set to NULL.
*/
rcu_assign_pointer(*slot, entry);
- if (xa_is_node(next))
+ if (xa_is_node(next) && (!node || node->shift))
xas_free_nodes(xas, xa_to_node(next));
if (!node)
break;
--
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