Thanks to the evil Intel AMT serial, I've been able to figure out what
made my x220 hang when suspending. Turns out that the fix matthew@
committed almost two weeks ago uncovered another bug that made
sched_stop_secondary_cpus() spin forever if there was a processing
running on a secondary cpu but nothing left on the run qeueue. In
that case sched_choosecpu() short-circuits and returns the current
cpu. The fix is obvious: don't short-circuit when we're on a cpu that
should stop.
ok?
Index: kern_sched.c
===================================================================
RCS file: /home/cvs/src/sys/kern/kern_sched.c,v
retrieving revision 1.33
diff -u -p -r1.33 kern_sched.c
--- kern_sched.c 13 Jul 2014 21:44:58 -0000 1.33
+++ kern_sched.c 26 Jul 2014 11:44:26 -0000
@@ -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);
