sparse is unhappy about this code in hlist_add_tail_rcu:
struct hlist_node *i, *last = NULL;
for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i))
last = i;
This is because hlist_next_rcu and hlist_next_rcu return
__rcu pointers.
It's a false positive - it's a write side primitive and so
does not need to be called in a read side critical section.
The following trivial patch disables the warning
without changing the behaviour in any way.
Note: __hlist_for_each_rcu would also remove the warning but it would be
confusing since it calls rcu_derefence and is designed to run in the rcu
read side critical section.
Signed-off-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
---
Comments from v2:
add a comment as requested by Steven Rostedt
include/linux/rculist.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 4f7a956..b1fd8bf 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -509,7 +509,8 @@ static inline void hlist_add_tail_rcu(struct hlist_node *n,
{
struct hlist_node *i, *last = NULL;
- for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i))
+ /* Note: write side code, so rcu accessors are not needed. */
+ for (i = h->first; i; i = i->next)
last = i;
if (last) {
--
MST
