mps(4) blocks panic-reboot

[Harry Schmalzbauer]

 Bezüglich Harry Schmalzbauer's Nachricht vom 01.06.2017 21:03 (localtime):
> Bezüglich Stephen Mcconnell's Nachricht vom 01.06.2017 19:36 (localtime):
>> Can you try the attached patch and let me know how it goes? I didn't test
>> it, but since you know how, it might be easier this way. This was diff'd
>> from the latest mps files in stable/11, which I recently updated (today).
> Your diff is doing very well on r319447:
>
>
…
> mps0: Sending StopUnit: path (xpt0:mps0:0:6:ffffffff):  handle 13
> mps0: Completing stop unit for (xpt0:mps0:0:6:ffffffff):
>
> And, there followed a immediate reset :-)

There's one new problem: Shutting down leads to the probably last panic
possible:

kernel trap 12 with interrupts disabled

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0x20
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff805f43ec
stack pointer           = 0x28:0xfffffe03bc9c3730
frame pointer           = 0x28:0xfffffe03bc9c3750
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = resume, IOPL = 0
current process         = 1 (init)
trap number             = 12
panic: page fault
cpuid = 0
KDB: stack backtrace:
#0 0xffffffff805df4f7 at kdb_backtrace+0x67
#1 0xffffffff8059df96 at vpanic+0x186
#2 0xffffffff8059de03 at panic+0x43
#3 0xffffffff808a1892 at trap_fatal+0x322
#4 0xffffffff808a18e9 at trap_pfault+0x49
#5 0xffffffff808a1126 at trap+0x286
#6 0xffffffff80887401 at calltrap+0x8
#7 0xffffffff805800f2 at __mtx_unlock_sleep+0x72
#8 0xffffffff8029a7dc at xpt_polled_action+0x31c
#9 0xffffffff80416c2b at mpssas_ir_shutdown+0x51b
#10 0xffffffff8059db9a at kern_reboot+0x49a
#11 0xffffffff8059d6f8 at sys_reboot+0x458
#12 0xffffffff808a23f4 at amd64_syscall+0x6c4
#13 0xffffffff808876eb at Xfast_syscall+0xfb

(kgdb) list *0xffffffff805f43ec                   
0xffffffff805f43ec is in turnstile_broadcast
(/usr/local/share/deploy-tools/RELENG_11/src/sys/kern/subr_turnstile.c:837).
832
833             /*
834              * Transfer the blocked list to the pending list.
835              */
836             mtx_lock_spin(&td_contested_lock);
837             TAILQ_CONCAT(&ts->ts_pending, &ts->ts_blocked[queue],
td_lockq);
838             mtx_unlock_spin(&td_contested_lock);
839
840             /*
841              * Give a turnstile to each thread.  The last thread gets

I haven't looked at the code at all and only very briefly lokked at the
diff, just out of curiosity, like pigs staring at clockworks ;-)

But at least I hope this report does help.

Thanks,

-harry