From: Kairui Song kasong@tencent.com
maillist inclusion category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/I9JAY9 CVE: NA
Reference: https://lore.kernel.org/linux-mm/20240416071722.45997-1-ryncsn@gmail.com/#t
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It can be used after xas_load to check the order of loaded entries. Compared to xa_get_order, it saves an XA_STATE and avoid a rewalk.
Added new test for xas_get_order, to make the test work, we have to export xas_get_order with EXPORT_SYMBOL_GPL.
Also fix a sparse warning by checking the slot value with xa_entry instead of accessing it directly, as suggested by Matthew Wilcox.
Link: https://lkml.kernel.org/r/20240415171857.19244-4-ryncsn@gmail.com Signed-off-by: Kairui Song kasong@tencent.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Andrew Morton akpm@linux-foundation.org
Conflicts: lib/test_xarray.c
Signed-off-by: ZhangPeng zhangpeng362@huawei.com --- include/linux/xarray.h | 6 ++++++ lib/test_xarray.c | 34 +++++++++++++++++++++++++++++ lib/xarray.c | 49 ++++++++++++++++++++++++++---------------- 3 files changed, 71 insertions(+), 18 deletions(-)
diff --git a/include/linux/xarray.h b/include/linux/xarray.h index 89ec31f1f023..c3f54d2eaf36 100644 --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -1551,6 +1551,7 @@ void xas_create_range(struct xa_state *);
#ifdef CONFIG_XARRAY_MULTI int xa_get_order(struct xarray *, unsigned long index); +int xas_get_order(struct xa_state *xas); void xas_split(struct xa_state *, void *entry, unsigned int order); void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t); #else @@ -1559,6 +1560,11 @@ static inline int xa_get_order(struct xarray *xa, unsigned long index) return 0; }
+static inline int xas_get_order(struct xa_state *xas) +{ + return 0; +} + static inline void xas_split(struct xa_state *xas, void *entry, unsigned int order) { diff --git a/lib/test_xarray.c b/lib/test_xarray.c index e77d4856442c..2e229012920b 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1756,6 +1756,39 @@ static noinline void check_get_order(struct xarray *xa) } }
+static noinline void check_xas_get_order(struct xarray *xa) +{ + XA_STATE(xas, xa, 0); + + unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1; + unsigned int order; + unsigned long i, j; + + for (order = 0; order < max_order; order++) { + for (i = 0; i < 10; i++) { + xas_set_order(&xas, i << order, order); + do { + xas_lock(&xas); + xas_store(&xas, xa_mk_value(i)); + xas_unlock(&xas); + } while (xas_nomem(&xas, GFP_KERNEL)); + + for (j = i << order; j < (i + 1) << order; j++) { + xas_set_order(&xas, j, 0); + rcu_read_lock(); + xas_load(&xas); + XA_BUG_ON(xa, xas_get_order(&xas) != order); + rcu_read_unlock(); + } + + xas_lock(&xas); + xas_set_order(&xas, i << order, order); + xas_store(&xas, NULL); + xas_unlock(&xas); + } + } +} + static noinline void check_destroy(struct xarray *xa) { unsigned long index; @@ -1805,6 +1838,7 @@ static int xarray_checks(void) check_reserve(&xa0); check_multi_store(&array); check_get_order(&array); + check_xas_get_order(&array); check_xa_alloc(); check_find(&array); check_find_entry(&array); diff --git a/lib/xarray.c b/lib/xarray.c index f49053882354..84faa433cd24 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1751,39 +1751,52 @@ void *xa_store_range(struct xarray *xa, unsigned long first, EXPORT_SYMBOL(xa_store_range);
/** - * xa_get_order() - Get the order of an entry. - * @xa: XArray. - * @index: Index of the entry. + * xas_get_order() - Get the order of an loaded entry after xas_load. + * @xas: XArray operation state. + * + * Called after xas_load, the xas should not be in an error state. * * Return: A number between 0 and 63 indicating the order of the entry. */ -int xa_get_order(struct xarray *xa, unsigned long index) +int xas_get_order(struct xa_state *xas) { - XA_STATE(xas, xa, index); - void *entry; int order = 0;
- rcu_read_lock(); - entry = xas_load(&xas); - - if (!entry) - goto unlock; - - if (!xas.xa_node) - goto unlock; + if (!xas->xa_node) + return 0;
for (;;) { - unsigned int slot = xas.xa_offset + (1 << order); + unsigned int slot = xas->xa_offset + (1 << order);
if (slot >= XA_CHUNK_SIZE) break; - if (!xa_is_sibling(xas.xa_node->slots[slot])) + if (!xa_is_sibling(xas->xa_node->slots[slot])) break; order++; }
- order += xas.xa_node->shift; -unlock: + order += xas->xa_node->shift; + return order; +} +EXPORT_SYMBOL_GPL(xas_get_order); + +/** + * xa_get_order() - Get the order of an entry. + * @xa: XArray. + * @index: Index of the entry. + * + * Return: A number between 0 and 63 indicating the order of the entry. + */ +int xa_get_order(struct xarray *xa, unsigned long index) +{ + XA_STATE(xas, xa, index); + int order = 0; + void *entry; + + rcu_read_lock(); + entry = xas_load(&xas); + if (entry) + order = xas_get_order(&xas); rcu_read_unlock();
return order;