kernel/async.c: remove async_unregister_domain()

No callers in the tree.

Link: https://lkml.kernel.org/r/20210309151723.1907838-2-linux@rasmusvillemoes.dkSigned-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/async.h

@@ -112,7 +112,6 @@ async_schedule_dev_domain(async_func_t func, struct device *dev,
 	return async_schedule_node_domain(func, dev, dev_to_node(dev), domain);
 }
 
-void async_unregister_domain(struct async_domain *domain);
 extern void async_synchronize_full(void);
 extern void async_synchronize_full_domain(struct async_domain *domain);
 extern void async_synchronize_cookie(async_cookie_t cookie);

kernel/async.c

@@ -245,24 +245,6 @@ void async_synchronize_full(void)
 }
 EXPORT_SYMBOL_GPL(async_synchronize_full);
 
-/**
- * async_unregister_domain - ensure no more anonymous waiters on this domain
- * @domain: idle domain to flush out of any async_synchronize_full instances
- *
- * async_synchronize_{cookie|full}_domain() are not flushed since callers
- * of these routines should know the lifetime of @domain
- *
- * Prefer ASYNC_DOMAIN_EXCLUSIVE() declarations over flushing
- */
-void async_unregister_domain(struct async_domain *domain)
-{
-	spin_lock_irq(&async_lock);
-	WARN_ON(!domain->registered || !list_empty(&domain->pending));
-	domain->registered = 0;
-	spin_unlock_irq(&async_lock);
-}
-EXPORT_SYMBOL_GPL(async_unregister_domain);
-
 /**
  * async_synchronize_full_domain - synchronize all asynchronous function within a certain domain
  * @domain: the domain to synchronize