From 344da544f177f919cf6919e5abcd388f27aa53db Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@kernel.org>
Date: Fri, 16 Dec 2022 16:52:01 -0800
Subject: x86/nmi: Print reasons why backtrace NMIs are ignored

Instrument nmi_trigger_cpumask_backtrace() to dump out diagnostics based
on evidence accumulated by exc_nmi().  These diagnostics are dumped for
CPUs that ignored an NMI backtrace request for more than 10 seconds.

[ paulmck: Apply Ingo Molnar feedback. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <x86@kernel.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/nmi.h | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'include/linux/nmi.h')

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index f700ff2df074..048c0b9aa623 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -214,4 +214,12 @@ int proc_watchdog_cpumask(struct ctl_table *, int, void *, size_t *, loff_t *);
 #include <asm/nmi.h>
 #endif
 
+#ifdef CONFIG_NMI_CHECK_CPU
+void nmi_backtrace_stall_snap(const struct cpumask *btp);
+void nmi_backtrace_stall_check(const struct cpumask *btp);
+#else
+static inline void nmi_backtrace_stall_snap(const struct cpumask *btp) {}
+static inline void nmi_backtrace_stall_check(const struct cpumask *btp) {}
+#endif
+
 #endif
-- 
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