Date: Thu, 17 Nov 2011 13:02:03 -0800 From: mdf@FreeBSD.org To: Attilio Rao <attilio@freebsd.org> Cc: Kostik Belousov <kostikbel@gmail.com>, Alexander Motin <mav@freebsd.org>, freebsd-current@freebsd.org, Andriy Gapon <avg@freebsd.org> Subject: Re: Stop scheduler on panic Message-ID: <CAMBSHm-jne0qFb5A9ua1N_KOuc8O9e=pjX7_iwMG2dODzpy%2B_A@mail.gmail.com> In-Reply-To: <CAJ-FndB7-UeFVQhqe0sTnpJ2PhWO5ijaCLaE-6bzMU%2B8=gYXeg@mail.gmail.com> References: <20111113083215.GV50300@deviant.kiev.zoral.com.ua> <201111171137.18663.jhb@freebsd.org> <4EC53D1B.4000308@FreeBSD.org> <201111171409.37629.jhb@freebsd.org> <4EC563BB.60209@FreeBSD.org> <CAJ-FndB7-UeFVQhqe0sTnpJ2PhWO5ijaCLaE-6bzMU%2B8=gYXeg@mail.gmail.com>
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On Thu, Nov 17, 2011 at 12:54 PM, Attilio Rao <attilio@freebsd.org> wrote:
> 2011/11/17 Andriy Gapon <avg@freebsd.org>:
>> BTW, it is my opinion that we really should not let the debugger code call
>> mi_switch for any reason.
>
> Yes, I agree with this, this is why the sched_bind() in boot() is
> broken (immagine calling things like doadump from KDB. KDB right now
> can be thought as a first cut of this patch because it does disable
> the CPUs when entering the context, thus, the bug here is that if you
> stop all CPUs including CPU0 and later on you want bind on it you are
> death).
Another patch related to this area we have at $WORK:
#if defined(SMP)
- /*
- * Bind us to CPU 0 so that all shutdown code runs there. Some
- * systems don't shutdown properly (i.e., ACPI power off) if we
- * run on another processor.
- */
- thread_lock(curthread);
- sched_bind(curthread, 0);
- thread_unlock(curthread);
- KASSERT(PCPU_GET(cpuid) == 0, ("%s: not running on cpu 0", __func__));
+ /*
+ * sched_bind can't be done reliably inside of panic. cpu_reset() will
+ * rebind us in any case, more reliably.
+ */
+ if (panicstr == NULL) {
+ /*
+ * Bind us to CPU 0 so that all shutdown code runs there. Some
+ * systems don't shutdown properly (i.e., ACPI power off) if we
+ * run on another processor.
+ */
+ thread_lock(curthread);
+ sched_bind(curthread, 0);
+ thread_unlock(curthread);
+ KASSERT(PCPU_GET(cpuid) == 0, ("boot: not running on cpu 0"));
+ }
#endif
/* We're in the process of rebooting. */
rebooting = 1;
Cheers,
matthew
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