[PATCH v2 2/2] mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code

SeongJae Park
2023-04-15T03:32:23Z

The SLAB_TYPESAFE_BY_RCU example code snippet is having not tiny RCU
read-side critical section. 'Documentation/RCU/rculist_nulls.rst' has
similar example code snippet, and commit da82af04352b ("doc: Update and
wordsmith rculist_nulls.rst") has broken it. Apply the change to
SLAB_TYPESAFE_BY_RCU example code snippet, too.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
include/linux/slab.h | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index b18e56c6f06c..6acf1b7c6551 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -53,16 +53,18 @@
* stays valid, the trick to using this is relying on an independent
* object validation pass. Something like:
*
+ * begin:
* rcu_read_lock();
- * again:
* obj = lockless_lookup(key);
* if (obj) {
* if (!try_get_ref(obj)) // might fail for free objects
- * goto again;
+ * rcu_read_unlock();
+ * goto begin;
*
* if (obj->key != key) { // not the object we expected
* put_ref(obj);
- * goto again;
+ * rcu_read_unlock();
+ * goto begin;
* }
* }
* rcu_read_unlock();
--
2.25.1