Messages in this thread | | | Date | Tue, 24 Nov 2015 21:16:41 +0100 | From | Borislav Petkov <> | Subject | Re: [V5 PATCH 2/4] panic/x86: Allow cpus to save registers even if they are looping in NMI context |
| |
On Tue, Nov 24, 2015 at 02:37:00PM -0500, Steven Rostedt wrote: > On Tue, Nov 24, 2015 at 11:48:53AM +0100, Borislav Petkov wrote: > > > > > + */ > > > + while (!raw_spin_trylock(&nmi_reason_lock)) > > > + poll_crash_ipi_and_callback(regs); > > > > Waaait a minute: so if we're getting NMIs broadcasted on every core but > > we're *not* crash dumping, we will run into here too. This can't be > > right. :-\ > > This only does something if crash_ipi_done is set, which means you are killing > the box.
Yeah, Michal and I discussed that on IRC today. And yeah, it is really tricky stuff. So I appreciate it a lot you looking at it too. Thanks!
> But perhaps a comment that states that here would be useful, or maybe > just put in the check here. There's no need to make it depend on SMP, as > raw_spin_trylock() will turn to just ({1}) for UP, and that code wont even be > hit.
Right, this code needs much more thorough documentation to counter the trickiness.
Thanks.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
| |