From 2ee4c089741823aae794eaa2eb53780f65019981 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sat, 27 Oct 2018 20:00:12 +0200
Subject: [PATCH] devuart: don't sleep in uartdrainoutput() when called splhi
 or without a process

uartdrainoutput() might be called in early initialization
from uartctl() without a process.
---
 sys/src/9/port/devuart.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/sys/src/9/port/devuart.c b/sys/src/9/port/devuart.c
index 197e695f4..6cc9c46d8 100644
--- a/sys/src/9/port/devuart.c
+++ b/sys/src/9/port/devuart.c
@@ -318,9 +318,8 @@ uartdrained(void* arg)
 static void
 uartdrainoutput(Uart *p)
 {
-	if(!p->enabled)
+	if(!p->enabled || up == nil || !islo())
 		return;
-
 	p->drain = 1;
 	if(waserror()){
 		p->drain = 0;