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

Bart Van Assche
2018-03-19T20:19:52Z

On Mon, 2018-03-19 at 10:02 -0700, tj@kernel.org wrote:
> 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.

Hello Martin,

This was probably already clear to you, but anyway: please drop the patch at the
start of this thread.

Thanks,

Bart.