[PATCH v4 2/3] Docs/RCU/rculist_nulls: Fix hlist_[nulls]_head field names of 'obj'

From: SeongJae Park
Date: Fri Jun 16 2023 - 19:36:46 EST


The example code snippets on rculist_nulls.rst are assuming 'obj' to
have the 'hlist_head' or 'hlist_nulls_head' field named 'obj_node', but
a sentence and some code snippets are wrongly calling
'obj->obj_node.next' as 'obj->obj_next', or 'obj->obj_node' as 'member'.
Fix it.

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
Documentation/RCU/rculist_nulls.rst | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/RCU/rculist_nulls.rst b/Documentation/RCU/rculist_nulls.rst
index a6827cc31791..4afa11f2c906 100644
--- a/Documentation/RCU/rculist_nulls.rst
+++ b/Documentation/RCU/rculist_nulls.rst
@@ -63,7 +63,7 @@ but a version with an additional memory barrier (smp_rmb())
struct hlist_node *node, *next;
for (pos = rcu_dereference((head)->first);
pos && ({ next = pos->next; smp_rmb(); prefetch(next); 1; }) &&
- ({ obj = hlist_entry(pos, typeof(*obj), member); 1; });
+ ({ obj = hlist_entry(pos, typeof(*obj), obj_node); 1; });
pos = rcu_dereference(next))
if (obj->key == key)
return obj;
@@ -75,7 +75,7 @@ And note the traditional hlist_for_each_entry_rcu() misses this smp_rmb()::
struct hlist_node *node;
for (pos = rcu_dereference((head)->first);
pos && ({ prefetch(pos->next); 1; }) &&
- ({ obj = hlist_entry(pos, typeof(*obj), member); 1; });
+ ({ obj = hlist_entry(pos, typeof(*obj), obj_node); 1; });
pos = rcu_dereference(pos->next))
if (obj->key == key)
return obj;
@@ -95,7 +95,7 @@ Quoting Corey Minyard::
2) Insertion algorithm
----------------------

-We need to make sure a reader cannot read the new 'obj->obj_next' value
+We need to make sure a reader cannot read the new 'obj->obj_node.next' value
and previous value of 'obj->key'. Otherwise, an item could be deleted
from a chain, and inserted into another chain. If new chain was empty
before the move, 'next' pointer is NULL, and lockless reader can not
@@ -163,7 +163,7 @@ Note that using hlist_nulls means the type of 'obj_node' field of
head = &table[slot];
begin:
rcu_read_lock();
- hlist_nulls_for_each_entry_rcu(obj, node, head, member) {
+ hlist_nulls_for_each_entry_rcu(obj, node, head, obj_node) {
if (obj->key == key) {
if (!try_get_ref(obj)) { // might fail for free objects
rcu_read_unlock();
--
2.25.1