[PATCH] Oprofile: fix nmi_timer_int detection

From: Philippe Elie <phil.el@wanadoo.fr>

From: Zwane Mwaikambo <zwane@arm.linux.org.uk>

The nmi_timer_int oprofile driver was enabling itself unconditionally if an
SMP kernel was being used on a UP system without an IOAPIC.

Tested on a P5 using NMI timer int driver and UP system using timer int
driver both running an SMP kernel.

2004-02-11  Zwane Mwaikambo <zwane@arm.linux.org.uk>

	* arch/i386/kernel/nmi.c: export nmi_active
	* arch/i386/oprofile/nmi_timer_int.c: use it to check if owe can use
	  an nmi interrupt

arch/i386/kernel/nmi.c

@@ -42,7 +42,7 @@ extern void show_registers(struct pt_regs *regs);
  *     be enabled
  * -1: the lapic NMI watchdog is disabled, but can be enabled
  */
-static int nmi_active;
+int nmi_active;
 
 #define K7_EVNTSEL_ENABLE	(1 << 22)
 #define K7_EVNTSEL_INT		(1 << 20)
@@ -462,6 +462,7 @@ void nmi_watchdog_tick (struct pt_regs * regs)
 	}
 }
 
+EXPORT_SYMBOL(nmi_active);
 EXPORT_SYMBOL(nmi_watchdog);
 EXPORT_SYMBOL(disable_lapic_nmi_watchdog);
 EXPORT_SYMBOL(enable_lapic_nmi_watchdog);

arch/i386/oprofile/nmi_timer_int.c

@@ -48,9 +48,13 @@ static struct oprofile_operations nmi_timer_ops = {
 	.cpu_type = "timer"
 };
 
- 
 int __init nmi_timer_init(struct oprofile_operations ** ops)
 {
+	extern int nmi_active;
+
+	if (nmi_active <= 0)
+		return -ENODEV;
+
 	*ops = &nmi_timer_ops;
 	printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
 	return 0;

arch/x86_64/kernel/nmi.c

@@ -39,7 +39,7 @@
  *     be enabled
  * -1: the lapic NMI watchdog is disabled, but can be enabled
  */
-static int nmi_active;
+int nmi_active;		/* oprofile uses this */
 static int panic_on_timeout;
 
 unsigned int nmi_watchdog = NMI_LOCAL_APIC;
@@ -380,6 +380,7 @@ void unset_nmi_callback(void)
 	nmi_callback = dummy_nmi_callback;
 }
 
+EXPORT_SYMBOL(nmi_active);
 EXPORT_SYMBOL(nmi_watchdog);
 EXPORT_SYMBOL(disable_lapic_nmi_watchdog);
 EXPORT_SYMBOL(enable_lapic_nmi_watchdog);