On Thu Nov 10, 2022 at 10:35 AM AEST, Jordan Niethe wrote:

On Thu, 2022-07-28 at 16:31 +1000, Nicholas Piggin wrote:
<snip>

quoted

-#define queued_spin_lock queued_spin_lock
 
-static inline void queued_spin_unlock(struct qspinlock *lock)
+static __always_inline int queued_spin_trylock(struct qspinlock *lock)
 {
-	if (!IS_ENABLED(CONFIG_PARAVIRT_SPINLOCKS) || !is_shared_processor())
-		smp_store_release(&lock->locked, 0);
-	else
-		__pv_queued_spin_unlock(lock);
+	if (atomic_cmpxchg_acquire(&lock->val, 0, 1) == 0)
+		return 1;
+	return 0;

optional style nit: return (atomic_cmpxchg_acquire(&lock->val, 0, 1) == 0);

[resend as utf-8, not utf-7]

Thanks for the thorough review, apologies again it took me so long to
get back to.

I'm not completely sold on this. I guess it's already side-effects in a
control flow statement though... Maybe I will change it, not sure.

Thanks,
Nick