Introduce rwsleep(9), an equivalent to msleep(9) but for code protected

by a write lock.

ok guenther@, vgross@

1 files changed, 35 insertions, 1 deletions

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index 4e87d06b64b..beeefe06458 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_synch.c,v 1.134 2016/09/03 15:06:06 akfaew Exp $	*/
+/*	$OpenBSD: kern_synch.c,v 1.135 2016/09/13 08:32:44 mpi Exp $	*/
 /*	$NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $	*/
 
 /*
@@ -226,6 +226,40 @@ msleep(const volatile void *ident, struct mutex *mtx, int priority,
 	return (error);
 }
 
+/*
+ * Same as tsleep, but if we have a rwlock provided, then once we've
+ * entered the sleep queue we drop the it. After sleeping we re-lock.
+ */
+int
+rwsleep(const volatile void *ident, struct rwlock *wl, int priority,
+    const char *wmesg, int timo)
+{
+	struct sleep_state sls;
+	int error, error1;
+
+	KASSERT((priority & ~(PRIMASK | PCATCH | PNORELOCK)) == 0);
+	rw_assert_wrlock(wl);
+
+	sleep_setup(&sls, ident, priority, wmesg);
+	sleep_setup_timeout(&sls, timo);
+	sleep_setup_signal(&sls, priority);
+
+	rw_exit_write(wl);
+
+	sleep_finish(&sls, 1);
+	error1 = sleep_finish_timeout(&sls);
+	error = sleep_finish_signal(&sls);
+
+	if ((priority & PNORELOCK) == 0)
+		rw_enter_write(wl);
+
+	/* Signal errors are higher priority than timeouts. */
+	if (error == 0 && error1 != 0)
+		error = error1;
+
+	return (error);
+}
+
 void
 sleep_setup(struct sleep_state *sls, const volatile void *ident, int prio,
     const char *wmesg)