On 14.03.2024 08:20, Juergen Gross wrote:
> --- a/xen/common/spinlock.c
> +++ b/xen/common/spinlock.c
> @@ -395,14 +395,7 @@ static bool always_inline spin_is_locked_common(const
> spinlock_tickets_t *t)
>
> int _spin_is_locked(const spinlock_t *lock)
> {
> - /*
> - * Recursive locks may be locked by another CPU, yet we return
> - * "false" here, making this function suitable only for use in
> - * ASSERT()s and alike.
> - */
> - return lock->recurse_cpu == SPINLOCK_NO_CPU
> - ? spin_is_locked_common(&lock->tickets)
> - : lock->recurse_cpu == smp_processor_id();
> + return spin_is_locked_common(&lock->tickets);
> }
The "only suitable for ASSERT()s and alike" part of the comment wants
to survive here, I think.
> @@ -465,6 +458,23 @@ void _spin_barrier(spinlock_t *lock)
> spin_barrier_common(&lock->tickets, &lock->debug, LOCK_PROFILE_PAR);
> }
>
> +bool _rspin_is_locked(const rspinlock_t *lock)
> +{
> + /*
> + * Recursive locks may be locked by another CPU, yet we return
> + * "false" here, making this function suitable only for use in
> + * ASSERT()s and alike.
> + */
> + return lock->recurse_cpu == SPINLOCK_NO_CPU
> + ? spin_is_locked_common(&lock->tickets)
> + : lock->recurse_cpu == smp_processor_id();
> +}
Here otoh I wonder if both the comment and the spin_is_locked_common()
part of the condition are actually correct. Oh, the latter needs
retaining as long as we have nrspin_*() functions, I suppose. But the
comment could surely do with improving a little - at the very least
"yet we return "false"" isn't quite right; minimally there's a "may"
missing.
In principle, without any nrspin_*() functions, the result here ought
to be usable generally, not just for ASSERT()s. Whether having its
and _spin_is_locked()'s behavior differ would be a good idea is a
separate question, of course.
Jan
