XArray: add cmpxchg order test

XArray multi-index entries do not keep track of the order stored once the
entry is being marked as used with cmpxchg (conditionally replaced with
NULL).  Add a test to check the order is actually lost.  The test also
verifies the order and entries for all the tied indexes before and after
the NULL replacement with xa_cmpxchg.

Add another entry at 1 << order that keeps the node around and the order
information for the NULL-entry after xa_cmpxchg.

Link: https://lkml.kernel.org/r/20240131225125.1370598-3-mcgrof@kernel.org
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 1050e9113d2a5b88d8f54eeca94c5e16599362c0..ebe2af2e072db390b2c65e149969c65544476e16 100644 (file)
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -423,6 +423,59 @@ static noinline void check_cmpxchg(struct xarray *xa)
        XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static noinline void check_cmpxchg_order(struct xarray *xa)
+{
+#ifdef CONFIG_XARRAY_MULTI
+       void *FIVE = xa_mk_value(5);
+       unsigned int i, order = 3;
+
+       XA_BUG_ON(xa, xa_store_order(xa, 0, order, FIVE, GFP_KERNEL));
+
+       /* Check entry FIVE has the order saved */
+       XA_BUG_ON(xa, xa_get_order(xa, xa_to_value(FIVE)) != order);
+
+       /* Check all the tied indexes have the same entry and order */
+       for (i = 0; i < (1 << order); i++) {
+               XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
+               XA_BUG_ON(xa, xa_get_order(xa, i) != order);
+       }
+
+       /* Ensure that nothing is stored at index '1 << order' */
+       XA_BUG_ON(xa, xa_load(xa, 1 << order) != NULL);
+
+       /*
+        * Additionally, keep the node information and the order at
+        * '1 << order'
+        */
+       XA_BUG_ON(xa, xa_store_order(xa, 1 << order, order, FIVE, GFP_KERNEL));
+       for (i = (1 << order); i < (1 << order) + (1 << order) - 1; i++) {
+               XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
+               XA_BUG_ON(xa, xa_get_order(xa, i) != order);
+       }
+
+       /* Conditionally replace FIVE entry at index '0' with NULL */
+       XA_BUG_ON(xa, xa_cmpxchg(xa, 0, FIVE, NULL, GFP_KERNEL) != FIVE);
+
+       /* Verify the order is lost at FIVE (and old) entries */
+       XA_BUG_ON(xa, xa_get_order(xa, xa_to_value(FIVE)) != 0);
+
+       /* Verify the order and entries are lost in all the tied indexes */
+       for (i = 0; i < (1 << order); i++) {
+               XA_BUG_ON(xa, xa_load(xa, i) != NULL);
+               XA_BUG_ON(xa, xa_get_order(xa, i) != 0);
+       }
+
+       /* Verify node and order are kept at '1 << order' */
+       for (i = (1 << order); i < (1 << order) + (1 << order) - 1; i++) {
+               XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
+               XA_BUG_ON(xa, xa_get_order(xa, i) != order);
+       }
+
+       xa_store_order(xa, 0, BITS_PER_LONG - 1, NULL, GFP_KERNEL);
+       XA_BUG_ON(xa, !xa_empty(xa));
+#endif
+}
+
 static noinline void check_reserve(struct xarray *xa)
 {
        void *entry;
@@ -1976,6 +2029,7 @@ static int xarray_checks(void)
        check_xas_erase(&array);
        check_insert(&array);
        check_cmpxchg(&array);
+       check_cmpxchg_order(&array);
        check_reserve(&array);
        check_reserve(&xa0);
        check_multi_store(&array);