XArray: Fix xa_for_each with a single element at 0
The following sequence of calls would result in an infinite loop in
xa_find_after():
xa_store(xa, 0, x, GFP_KERNEL);
index = 0;
xa_for_each(xa, entry, index, ULONG_MAX, XA_PRESENT) { }
xa_find_after() was confusing the situation where we found no entry in
the tree with finding a multiorder entry, so it would look for the
successor entry forever. Just check for this case explicitly. Includes
a few new checks in the test suite to be sure this doesn't reappear.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index aa47754..1261276 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -702,7 +702,7 @@
}
}
-static noinline void check_find(struct xarray *xa)
+static noinline void check_find_1(struct xarray *xa)
{
unsigned long i, j, k;
@@ -748,6 +748,34 @@
XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_0));
}
XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static noinline void check_find_2(struct xarray *xa)
+{
+ void *entry;
+ unsigned long i, j, index = 0;
+
+ xa_for_each(xa, entry, index, ULONG_MAX, XA_PRESENT) {
+ XA_BUG_ON(xa, true);
+ }
+
+ for (i = 0; i < 1024; i++) {
+ xa_store_index(xa, index, GFP_KERNEL);
+ j = 0;
+ index = 0;
+ xa_for_each(xa, entry, index, ULONG_MAX, XA_PRESENT) {
+ XA_BUG_ON(xa, xa_mk_value(index) != entry);
+ XA_BUG_ON(xa, index != j++);
+ }
+ }
+
+ xa_destroy(xa);
+}
+
+static noinline void check_find(struct xarray *xa)
+{
+ check_find_1(xa);
+ check_find_2(xa);
check_multi_find(xa);
check_multi_find_2(xa);
}
diff --git a/lib/xarray.c b/lib/xarray.c
index 8b176f0..c991ff4 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1829,6 +1829,8 @@
entry = xas_find_marked(&xas, max, filter);
else
entry = xas_find(&xas, max);
+ if (xas.xa_node == XAS_BOUNDS)
+ break;
if (xas.xa_shift) {
if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
continue;