Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die_nmi path

Vivek Goyal
2008-02-06T22:49:22Z

On Wed, Feb 06, 2008 at 11:00:01PM +0100, Ingo Molnar wrote:
>
> * Neil Horman <nhorman@tuxdriver.com> wrote:
>
> > if (!user_mode_vm(regs)) {
> > + nmi_exit();
> > + local_irq_enable();
> > current->thread.trap_no = 2;
> > crash_kexec(regs);
>
> looks good to me, but please move the local_irq_enable() to within
> crash_kexec() instead - probably inside the "got the kexec lock"
> section. That makes crash_kexec() use generally safer too i guess: right
> it seems that die() too can call crash_kexec() with irqs disabled - and
> can thus hang in smp_send_stop() [or wherever it hung before].
>

In general, I think we should not be servicing interrupts once the system
has crashed and crash_kexec() has been invoked.

In fact, right now machine_crash_shutdown() explicity disables interrupt
before sending NMIs to other cpus to stop these cpus and which makes sense to
me.

I am wondering if interrupts are disabled on crashing cpu or if crashing
cpu is inside die_nmi(), how would it stop/prevent delivery of NMI IPI to
other cpus.

Am I missing something obivious?

Thanks
Vivek