1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index bc3a8e4a49f7..062716cf0f0c 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -332,6 +332,8 @@ int css_sch_is_valid(struct schib *schib)
 {
         if ((schib->pmcw.st == SUBCHANNEL_TYPE_IO) && !schib->pmcw.dnv)
                 return 0;
+        if ((schib->pmcw.st == SUBCHANNEL_TYPE_MSG) && !schib->pmcw.w)
+                return 0;
         return 1;
 }
 EXPORT_SYMBOL_GPL(css_sch_is_valid);