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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>
This commit is contained in:
Matthew Wilcox 2019-02-21 17:36:45 -05:00
parent 962033d55d
commit 2fbe967b3e
2 changed files with 16 additions and 2 deletions
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16
lib/test_xarray.c
View File

@ -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);

2
lib/xarray.c
View File

@ -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;