idr: Fix idr_alloc_u32 on 32-bit systems

Attempting to allocate an entry at 0xffffffff when one is already
present would succeed in allocating one at 2^32, which would confuse
everything.  Return -ENOSPC in this case, as expected.
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent f6341c5a
......@@ -1529,7 +1529,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
offset = radix_tree_find_next_bit(node, IDR_FREE,
offset + 1);
start = next_index(start, node, offset);
if (start > max)
if (start > max || start == 0)
return ERR_PTR(-ENOSPC);
while (offset == RADIX_TREE_MAP_SIZE) {
offset = node->offset + 1;
......
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