Re: [PATCH 2/2] xen: privcmd: Add support for ioeventfd

From: Viresh Kumar
Date: Mon Oct 09 2023 - 06:53:27 EST


On 09-10-23, 10:40, Alex Bennée wrote:
> I thought generally sync points act as full barriers. Doing a bunch of
> grepping I think ends at:
>
> static __always_inline bool __mutex_unlock_fast(struct mutex *lock)
> {
> unsigned long curr = (unsigned long)current;
>
> return atomic_long_try_cmpxchg_release(&lock->owner, &curr, 0UL);
> }
>
> so you should already have completed your writes by that point.

I am not sure if depending on such indirect mechanisms to implement
barriers for you is a good idea.

The situation here probably requires explicit barriers to make sure it
doesn't break in future ?

--
viresh