From: SeongJae Park <sj@kernel.org>
Date: Mon, 17 Apr 2023 19:04:50 +0000 (+0000)
Subject: mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1143c9d9d7602f20ba7bb3cef0d07b10f23cbef7;p=linux.git

mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code

The SLAB_TYPESAFE_BY_RCU example code snippet uses a single RCU
read-side critical section for retries.
'Documentation/RCU/rculist_nulls.rst' has similar example code snippet,
and commit da82af04352b ("doc: Update and wordsmith rculist_nulls.rst")
broke it up.  Apply the change to SLAB_TYPESAFE_BY_RCU example code
snippet, too.

Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 5eeedbfffcd29..c6bc05765bdb2 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();