x86, NMI watchdog: add support to enable and disable IOAPIC NMI

Impact: change/improve the way /proc/sys/kernel/nmi_watchdog works

This patch adds support to enable/disable IOAPIC NMI watchdog in runtime via
procfs.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 2c97f07..2c005fa 100644 (file)
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -340,6 +340,8 @@ void stop_apic_nmi_watchdog(void *unused)
                return;
        if (nmi_watchdog == NMI_LOCAL_APIC)
                lapic_watchdog_stop();
+       else
+               __acpi_nmi_disable(NULL);
        __get_cpu_var(wd_enabled) = 0;
        atomic_dec(&nmi_active);
 }
@@ -465,6 +467,24 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
 
 #ifdef CONFIG_SYSCTL
 
+static void enable_ioapic_nmi_watchdog_single(void *unused)
+{
+       __get_cpu_var(wd_enabled) = 1;
+       atomic_inc(&nmi_active);
+       __acpi_nmi_enable(NULL);
+}
+
+static void enable_ioapic_nmi_watchdog(void)
+{
+       on_each_cpu(enable_ioapic_nmi_watchdog_single, NULL, 1);
+       touch_nmi_watchdog();
+}
+
+static void disable_ioapic_nmi_watchdog(void)
+{
+       on_each_cpu(stop_apic_nmi_watchdog, NULL, 1);
+}
+
 static int __init setup_unknown_nmi_panic(char *str)
 {
        unknown_nmi_panic = 1;
@@ -507,6 +527,11 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
                        enable_lapic_nmi_watchdog();
                else
                        disable_lapic_nmi_watchdog();
+       } else if (nmi_watchdog == NMI_IO_APIC) {
+               if (nmi_watchdog_enabled)
+                       enable_ioapic_nmi_watchdog();
+               else
+                       disable_ioapic_nmi_watchdog();
        } else {
                printk(KERN_WARNING
                        "NMI watchdog doesn't know what hardware to touch\n");