On 2024-10-07 15:47, Boqun Feng wrote:
On Thu, Oct 03, 2024 at 09:30:53AM -0400, Mathieu Desnoyers wrote:
[...]
+ /*
+ * Use RCU dereference without lockdep checks, because
+ * lockdep is not aware of HP guarantees.
+ */
+ addr2 = rcu_access_pointer(*addr_p); /* Load A */
Why rcu_access_pointer() instead of READ_ONCE()? Because you want to
mark the head of address dependency?
Yes, the intent here is to mark the address dependency and provide
a publication guarantee similar to RCU pairing rcu_assign_pointer
and rcu_dereference. Do you see any reason why READ_ONCE() would
suffice here ?
READ_ONCE() also provides address dependencies. See the "DEPENDENCY
RELATIONS: data, addr, and ctrl" section in
tools/memory-model/Documentation/explanantion.txt.
Fair point, so let's use READ_ONCE() then.
Thanks,
Mathieu
Regards,
Boqun
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com