2 files changed, 17 insertions, 9 deletions

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 32acda25e3cb..8dfe9db87a9e 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -119,10 +119,7 @@ int __init check_nmi_watchdog(void)
         unsigned int *prev_nmi_count;
         int cpu;
 
-        if (nmi_watchdog == NMI_NONE)
-                return 0;
-
-        if (!atomic_read(&nmi_active))
+        if (!nmi_watchdog_active() || !atomic_read(&nmi_active))
                 return 0;
 
         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
@@ -317,8 +314,7 @@ void setup_apic_nmi_watchdog(void *unused)
 void stop_apic_nmi_watchdog(void *unused)
 {
         /* only support LOCAL and IO APICs for now */
-        if (nmi_watchdog != NMI_LOCAL_APIC &&
-            nmi_watchdog != NMI_IO_APIC)
+        if (!nmi_watchdog_active())
                 return;
         if (__get_cpu_var(wd_enabled) == 0)
                 return;
@@ -348,8 +344,7 @@ static DEFINE_PER_CPU(int, nmi_touch);
 
 void touch_nmi_watchdog(void)
 {
-        if (nmi_watchdog == NMI_LOCAL_APIC ||
-                nmi_watchdog == NMI_IO_APIC) {
+        if (nmi_watchdog_active()) {
                 unsigned cpu;
 
                 /*
@@ -474,7 +469,7 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
         if (!!old_state == !!nmi_watchdog_enabled)
                 return 0;
 
-        if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_NONE) {
+        if (atomic_read(&nmi_active) < 0 || !nmi_watchdog_active()) {
                 printk(KERN_WARNING
                         "NMI watchdog is permanently disabled\n");
                 return -EIO;
diff --git a/include/asm-x86/nmi.h b/include/asm-x86/nmi.h
index 1348e542360f..21f8d0202a82 100644
--- a/include/asm-x86/nmi.h
+++ b/include/asm-x86/nmi.h
@@ -56,6 +56,19 @@ static inline void localise_nmi_watchdog(void)
         if (nmi_watchdog == NMI_IO_APIC)
                 nmi_watchdog = NMI_LOCAL_APIC;
 }
+
+/* check if nmi_watchdog is active (ie was specified at boot) */
+static inline int nmi_watchdog_active(void)
+{
+        /*
+         * actually it should be:
+         *      return (nmi_watchdog == NMI_LOCAL_APIC ||
+         *              nmi_watchdog == NMI_IO_APIC)
+         * but since they are power of two we could use a
+         * cheaper way --cvg
+         */
+        return nmi_watchdog & 0x3;
+}
 #endif
 
 void lapic_watchdog_stop(void);