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    SubjectSleeping in RCU list traversal
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    Hello.

    Peter Zijlstra wrote:
    > > Can I sleep between rcu_read_lock() and rcu_read_unlock() ?
    > > As far as I saw, rcu_read_lock() makes in_atomic() true, so I think I can't sleep.
    > You can indeed not sleep in an rcu_read_lock() section. However, you
    > could grab a reference on an item, stop the iteration, drop
    > rcu_read_lock. Do you thing, re-acquire rcu_read_lock(), drop the ref,
    > and continue the iteration.

    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" ?

    Regards.

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