On Fri, Feb 28, 2025, Sean Christopherson wrote:
> On Fri, Feb 28, 2025, Lei Yang wrote:
> > Hi Keith
> >
> > V3 introduced a new bug, the following error messages from qemu output
> > after applying this patch to boot up a guest.
>
> Doh, my bug. Not yet tested, but this should fix things. Assuming it does, I'll
> post a v3 so I can add my SoB.
v4
Confirmed that it worked, but deleting the pre-mutex check for ONCE_COMPLETED.
Will post v4 later today.
> diff --git a/include/linux/call_once.h b/include/linux/call_once.h
> index ddcfd91493ea..b053f4701c94 100644
> --- a/include/linux/call_once.h
> +++ b/include/linux/call_once.h
> @@ -35,10 +35,12 @@ static inline int call_once(struct once *once, int (*cb)(struct once *))
> return 0;
>
> guard(mutex)(&once->lock);
> - WARN_ON(atomic_read(&once->state) == ONCE_RUNNING);
> - if (atomic_read(&once->state) != ONCE_NOT_STARTED)
> + if (WARN_ON(atomic_read(&once->state) == ONCE_RUNNING))
> return -EINVAL;
>
> + if (atomic_read(&once->state) == ONCE_COMPLETED)
> + return 0;
> +
> atomic_set(&once->state, ONCE_RUNNING);
> r = cb(once);
> if (r)
