s390x/css: sch_handle_start_func() handles resume, too

It's not obvious from the code flow that sch_handle_start_func() gets
called for rsch. Add some comments explaining this.

Signed-off-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 9e98f50..bb8e4be 100644 (file)
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -511,6 +511,7 @@ static void sch_handle_start_func(SubchDev *sch, ORB *orb)
     path = 0x80;
 
     if (!(s->ctrl & SCSW_ACTL_SUSP)) {
+        /* Start Function triggered via ssch, i.e. we have an ORB */
         s->cstat = 0;
         s->dstat = 0;
         /* Look at the orb and try to execute the channel program. */
@@ -528,6 +529,8 @@ static void sch_handle_start_func(SubchDev *sch, ORB *orb)
         sch->ccw_no_data_cnt = 0;
         suspend_allowed = !!(orb->ctrl0 & ORB_CTRL0_MASK_SPND);
     } else {
+        /* Start Function resumed via rsch, i.e. we don't have an
+         * ORB */
         s->ctrl &= ~(SCSW_ACTL_SUSP | SCSW_ACTL_RESUME_PEND);
         /* The channel program had been suspended before. */
         suspend_allowed = true;
@@ -610,6 +613,7 @@ static void do_subchannel_work(SubchDev *sch, ORB *orb)
     } else if (s->ctrl & SCSW_FCTL_HALT_FUNC) {
         sch_handle_halt_func(sch);
     } else if (s->ctrl & SCSW_FCTL_START_FUNC) {
+        /* Triggered by both ssch and rsch. */
         sch_handle_start_func(sch, orb);
     } else {
         /* Cannot happen. */