suspend-related shceduler fix

[Mark Kettenis]

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.c13 Jul 2014 21:44:58 -  1.33
+++ kern_sched.c26 Jul 2014 11:44:26 -
@@ -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);

Re: suspend-related shceduler fix

[Brent Cook]

This cures my x220 as well. OK bcook@
On Jul 26, 2014 6:56 AM, Mark Kettenis mark.kette...@xs4all.nl wrote:

 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.c13 Jul 2014 21:44:58 -  1.33
 +++ kern_sched.c26 Jul 2014 11:44:26 -
 @@ -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);

Re: suspend-related shceduler fix

[Philip Guenther]

On Sat, Jul 26, 2014 at 4:56 AM, Mark Kettenis mark.kette...@xs4all.nl
wrote:

 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?


ok guenther@