Re: [PATCH] Change synchronize_rcu() in scsi_device_quiesce() into synchronize_sched()

tj
2018-03-19T17:02:25Z

Hey,

On Mon, Mar 19, 2018 at 04:57:45PM +0000, Bart Van Assche wrote:
> For synchronization primitives that wait having a stronger synchronization
> primitive nested inside a more relaxed one can lead to a deadlock. But since
> the rcu read lock primitives do not wait it could be safe to use that kind
> of nesting with RCU. Do you perhaps know whether any documentation is
> available about that kind of nesting or whether it is already used elsewhere
> in the kernel?

Oh, we nest them all the time. They're like (and sometimes literally
are) preempt_disable() and don't care about nest ordering.

Thanks.

--
tejun