[PATCH] x86: Add abilty to enable/disable nmi watchdog from procfs (update)

Adds a new /proc/sys/kernel/nmi_watchdog call that will enable/disable the
nmi watchdog.

By entering a non-zero value here, a user can enable the nmi watchdog to
monitor the online cpus in the system.  By entering a zero value here, a
user can disable the nmi watchdog and free up a performance counter which
could then be utilized by the oprofile subsystem, otherwise oprofile may be
short a counter when in use.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>

1 files changed, 4 insertions, 17 deletions

diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index 28065d0b71a9..6241e4448cab 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -847,7 +847,7 @@ static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
 }
 
 /*
- * proc handler for /proc/sys/kernel/nmi_watchdog
+ * proc handler for /proc/sys/kernel/nmi
  */
 int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
                         void __user *buffer, size_t *length, loff_t *ppos)
@@ -861,8 +861,8 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
                 return 0;
 
         if (atomic_read(&nmi_active) < 0) {
-                printk(KERN_WARNING "NMI watchdog is permanently disabled\n");
-                return -EINVAL;
+                printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
+                return -EIO;
         }
 
         if (nmi_watchdog == NMI_DEFAULT) {
@@ -872,24 +872,11 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
                         nmi_watchdog = NMI_IO_APIC;
         }
 
-        if (nmi_watchdog == NMI_LOCAL_APIC)
-        {
+        if (nmi_watchdog == NMI_LOCAL_APIC) {
                 if (nmi_watchdog_enabled)
                         enable_lapic_nmi_watchdog();
                 else
                         disable_lapic_nmi_watchdog();
-        } else if (nmi_watchdog == NMI_IO_APIC) {
-                /* FIXME
-                 * for some reason these functions don't work
-                 */
-                printk("Can not enable/disable NMI on IO APIC\n");
-                return -EINVAL;
-#if 0
-                if (nmi_watchdog_enabled)
-                        enable_timer_nmi_watchdog();
-                else
-                        disable_timer_nmi_watchdog();
-#endif
         } else {
                 printk( KERN_WARNING
                         "NMI watchdog doesn't know what hardware to touch\n");