Re: sched_4bsd startup crash trying to run a bound thread on an AP that hasn't started

On Wed, Apr 6, 2011 at 2:29 PM, John Baldwin <jhb_at_freebsd.org> wrote:
> I guess one other option would be something like this:
>
>                if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
>                    ts->ts_flags & TSF_AFFINITY)) {
>                        if (td->td_pinned != 0)
>                                cpu = td->td_lastcpu;
>                        else if (td->td_flags & TDF_BOUND) {
>                                /* Find CPU from bound runq. */
>                                KASSERT(...);
>                                cpu = ts->ts_runq - &runq_pcpu[0];
>                        } else
>                                /* Find a valid CPU for our cpuset. */
>                                cpu = sched_pickcpu(td);
>                        ts->ts_runq = &runq_pcpu[cpu];
>                        single_cpu = 1;
>                        CTR3(KTR_RUNQ, ...);
>                } else {
>                        /* Global runq case. */
>                }
>
> This also avoids duplicating some common code to all the single_cpu cases.
>
> --
> John Baldwin
>

I went with this option.  Does this look right?

Index: sys/kern/sched_4bsd.c
===================================================================
--- sys/kern/sched_4bsd.c       (revision 220603)
+++ sys/kern/sched_4bsd.c       (working copy)
_at__at_ -1246,30 +1246,28 _at__at_
        }
        TD_SET_RUNQ(td);

-       if (td->td_pinned != 0) {
-               cpu = td->td_lastcpu;
+       /*
+        * If SMP is not started, don't obey any requested CPU pinning as that
+        * CPU has either not yet started or it is curcpu.  Trying to run a
+        * thread on a CPU that has not yet started will panic the system.
+        */
+       if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
+           ts->ts_flags & TSF_AFFINITY)) {
+               if (td->td_pinned != 0)
+                       cpu = td->td_lastcpu;
+               else if (td->td_flags & TDF_BOUND) {
+                       /* Find CPU from bound runq. */
+                       KASSERT(SKE_RUNQ_PCPU(ts),
+                           ("sched_add: bound td_sched not on cpu runq"));
+                       cpu = ts->ts_runq - &runq_pcpu[0];
+               } else
+                       /* Find a valid CPU for our cpuset */
+                       cpu = sched_pickcpu(td);
                ts->ts_runq = &runq_pcpu[cpu];
                single_cpu = 1;
                CTR3(KTR_RUNQ,
                    "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
                    cpu);
-       } else if (td->td_flags & TDF_BOUND) {
-               /* Find CPU from bound runq. */
-               KASSERT(SKE_RUNQ_PCPU(ts),
-                   ("sched_add: bound td_sched not on cpu runq"));
-               cpu = ts->ts_runq - &runq_pcpu[0];
-               single_cpu = 1;
-               CTR3(KTR_RUNQ,
-                   "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
-                   cpu);
-       } else if (ts->ts_flags & TSF_AFFINITY) {
-               /* Find a valid CPU for our cpuset */
-               cpu = sched_pickcpu(td);
-               ts->ts_runq = &runq_pcpu[cpu];
-               single_cpu = 1;
-               CTR3(KTR_RUNQ,
-                   "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
-                   cpu);
        } else {
                CTR2(KTR_RUNQ,
                    "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,