diff options
| author | Dev Jain <dev.jain@arm.com> | 2025-06-04 09:45:33 +0530 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-07-09 22:42:02 -0700 |
| commit | 1e6b17b4237dacb02e9cfeaed35d889bbc9e8a84 (patch) | |
| tree | 84f34e1355042c3a32c9acdc1ebe91fcff694a0b /lib/xarray.c | |
| parent | ff7ec8dc1b646296f8d94c39339e8d3833d16c05 (diff) | |
xarray: add a BUG_ON() to ensure caller is not sibling
Suppose xas is pointing somewhere near the end of the multi-entry batch.
Then it may happen that the computed slot already falls beyond the batch,
thus breaking the loop due to !xa_is_sibling(), and computing the wrong
order.
For example, suppose we have a shift-6 node having an order-9 entry => 8 -
1 = 7 siblings, so assume the slots are at offset 0 till 7 in this node.
If xas->xa_offset is 6, then the code will compute order as 1 +
xas->xa_node->shift = 7. Therefore, the order computation must start from
the beginning of the multi-slot entries, that is, the non-sibling entry.
Thus ensure that the caller is aware of this by triggering a BUG when the
entry is a sibling entry. Note that this BUG_ON() is only active while
running selftests, so there is no overhead in a running kernel.
Link: https://lkml.kernel.org/r/20250604041533.91198-1-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib/xarray.c')
| -rw-r--r-- | lib/xarray.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/xarray.c b/lib/xarray.c index 76dde3a1cacf..ae3d80f4b4ee 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1910,6 +1910,7 @@ EXPORT_SYMBOL(xa_store_range); * @xas: XArray operation state. * * Called after xas_load, the xas should not be in an error state. + * The xas should not be pointing to a sibling entry. * * Return: A number between 0 and 63 indicating the order of the entry. */ @@ -1920,6 +1921,8 @@ int xas_get_order(struct xa_state *xas) if (!xas->xa_node) return 0; + XA_NODE_BUG_ON(xas->xa_node, xa_is_sibling(xa_entry(xas->xa, + xas->xa_node, xas->xa_offset))); for (;;) { unsigned int slot = xas->xa_offset + (1 << order); |