If we're stopping a secondary cpu, don't let sched_choosecpu() short-circuit

and return the current current CPU, otherwise sched_stop_secondary_cpus()
will spin forever trying to empty its run queues.  Fixes hangs during suspend
that many people reported over the last couple of days.

ok bcook@, guenther@

diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index 6717726..6047611 100644 (file)
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_sched.c,v 1.33 2014/07/13 21:44:58 matthew Exp $ */
+/*     $OpenBSD: kern_sched.c,v 1.34 2014/07/26 16:07:39 kettenis Exp $        */
 /*
  * Copyright (c) 2007, 2008 Artur Grabowski <art@openbsd.org>
  *
@@ -275,6 +275,7 @@ sched_chooseproc(void)
                                while ((p = TAILQ_FIRST(&spc->spc_qs[queue]))) {
                                        remrunqueue(p);
                                        p->p_cpu = sched_choosecpu(p);
+                                       KASSERT(p->p_cpu != curcpu());
                                        setrunqueue(p);
                                }
                        }
@@ -408,6 +409,7 @@ sched_choosecpu(struct proc *p)
         */
        if (cpuset_isset(&set, p->p_cpu) ||
            (p->p_cpu == curcpu() && p->p_cpu->ci_schedstate.spc_nrun == 0 &&
+           (p->p_cpu->ci_schedstate.spc_schedflags & SPCF_SHOULDHALT) == 0 &&
            curproc == p)) {
                sched_wasidle++;
                return (p->p_cpu);