> @@ -357,7 +358,15 @@ static void default_do_nmi(struct pt_regs *regs) > } > > /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */ > - raw_spin_lock(&nmi_reason_lock); > + > + /* > + * Another CPU may be processing panic routines with holding > + * nmi_reason_lock. Check IPI issuance from the panicking CPU > + * and call the callback directly. > + */ > + while (!raw_spin_trylock(&nmi_reason_lock)) > + poll_crash_ipi_and_callback(regs); > + > reason = x86_platform.get_nmi_reason();
I noticed this logic is unneeded until applying PATCH 4/4. Currently, unknown NMI can be broadcast to all CPUs, but in that case, panic()/nmi_panic() are called after releasing nmi_reason_lock. So CPUs can't loop infinitely here. PATCH 4/4 allows us to broadcast external NMIs to all CPUs, and it causes infinite loop in raw_spin_lock(&nmi_reason_lock). So the above changes are needed. I'll move these chagnes to a later patch in the next version. Thanks, -- Hidehiro Kawai Hitachi, Ltd. Research & Development Group
