Re: [RFC] locking/rwsem: Avoid issuing wakeup before setting the reader waiter to nil

Davidlohr Bueso
2018-12-18T17:27:26Z

On Tue, 18 Dec 2018, Peter Zijlstra wrote:
>> I'd rather do it like so, except I'm still conflicted on the naming.
>
>> +void wake_q_add(struct wake_q_head *head, struct task_struct *task)
>> +{
>> + if (__wake_q_add(head, task))
>> + get_task_struct(task);
>> +}
>> +
>> +void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task)
>> +{
>> + if (!__wake_a_add(head, task))
>> + put_task_struct(task);
>> }
>
>That is, in the one case it has internal reference counting, in the
>other case it consumes the reference counting.

Yeah I like that better for an interface. Also no concurrency in head
so delaying the get() should be ok.

Thanks,
Davidlohr