Re: [PATCH] NMI watchdog: setup before enabling NMI watchdog

From: Cyrill Gorcunov
Date: Mon Sep 22 2008 - 14:05:52 EST


[Aristeu Rozanski - Mon, Sep 22, 2008 at 01:13:59PM -0400]
| There's a small window when NMI watchdog is being set up that if any NMIs
| are triggered, the NMI code will make make use of not initalized wd_ops
| elements:

Hi Aristeu,

thanks for the patch! I may be _absolutely_ wrong but could you
explain me how we reach this site in traps

---
if (!(reason & 0xc0)) {
if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason,
2, SIGINT) == NOTIFY_STOP)
return;
/*
* Ok, so this is none of the documented NMI sources,
* so it must be the NMI watchdog.
^^^^
*/
if (nmi_watchdog_tick(regs, reason))
return;
if (!do_nmi_callback(regs, cpu))
unknown_nmi_error(reason, regs);

return;
}
---

not having masked APIC registers as NMI entry yet (which is done during
perfctl initialization)?

- Cyrill -
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