Hi
>Something like this?
>
>rcu_read_lock();
>list_for_each_rcu(p, ...) {
> ptr = list_entry(p, struct ..., list);
> /* Grab a reference to "ptr". */
> rcu_read_unlock();
> my_task_that_may_sleep(ptr);
> rcu_read_lock();
> /* Drop a reference to "ptr". */
>}
>rcu_read_unlock();
>Regarding my case, memory region pointed by "ptr" never be removed.
>Do I need to grab a reference to "ptr" ?
In Document/RCU/whatisRCU.txt
Note that the value returned by rcu_dereference() is valid
only within the enclosing RCU read-side critical section.
For example, the following is -not- legal:
rcu_read_lock();
p = rcu_dereference(head.next);
rcu_read_unlock();
x = p->address;
rcu_read_lock();
y = p->data;
rcu_read_unlock();
Holding a reference from one RCU read-side critical section
to another is just as illegal as holding a reference from
one lock-based critical section to another! Similarly,
using a reference outside of the critical section in which
it was acquired is just as illegal as doing so with normal
locking.
Jun Wang
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