Re: [PATCH V4 7/9] vhost: do not use RCU to synchronize MMU notifier with worker

From: Jason Gunthorpe
Date: Thu Aug 08 2019 - 09:05:29 EST

On Thu, Aug 08, 2019 at 08:54:54PM +0800, Jason Wang wrote:

> I don't have any objection to convert to spinlock() but just want to
> know if any case that the above smp_mb() + counter looks good to you?

This email is horribly mangled, but I don't think mixing smb_mb() and
smp_load_acquire() would be considerd a best-practice, and using
smp_store_release() instead would be the wrong barrier.

spinlock does seem to be the only existing locking primitive that does
what is needed here.