x86, nmi: Track NMI usage stats

Now that the NMI handler are broken into lists, increment the appropriate
stats for each list. This allows us to see what is going on when they
get printed out in the next patch.

Signed-off-by: Don Zickus <[e-mail]>
Signed-off-by: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/kernel/nmi.c

···
 
 };
 
+struct nmi_stats {
+	unsigned int normal;
+	unsigned int unknown;
+	unsigned int external;
+	unsigned int swallow;
+};
+
+static DEFINE_PER_CPU(struct nmi_stats, nmi_stats);
+
 static int ignore_nmis;
 
 int unknown_nmi_panic;
···
 	 * if it caused the NMI)
 	 */
 	handled = nmi_handle(NMI_UNKNOWN, regs, false);
-	if (handled)
+	if (handled) {
+		__this_cpu_add(nmi_stats.unknown, handled);
 		return;
+	}
+
+	__this_cpu_add(nmi_stats.unknown, 1);
+
 #ifdef CONFIG_MCA
 	/*
 	 * Might actually be able to figure out what the guilty party
···
 	__this_cpu_write(last_nmi_rip, regs->ip);
 
 	handled = nmi_handle(NMI_LOCAL, regs, b2b);
+	__this_cpu_add(nmi_stats.normal, handled);
 	if (handled) {
 		/*
 		 * There are cases when a NMI handler handles multiple
···
 		 */
 		reassert_nmi();
 #endif
+		__this_cpu_add(nmi_stats.external, 1);
 		raw_spin_unlock(&nmi_reason_lock);
 		return;
 	}
···
 	 * for now.
 	 */
 	if (b2b && __this_cpu_read(swallow_nmi))
-		;
+		__this_cpu_add(nmi_stats.swallow, 1);
 	else
 		unknown_nmi_error(reason, regs);
 }