Re: [PATCHv3 0/2]

Sean Christopherson
2025-02-28T14:15:22Z

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.

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)