x86_64: Fix to keep watchdog disabled by default for i386/x86_64

Fixed wrong expression which enabled watchdogs even if nmi_watchdog kernel
parameter wasn't set. This regression got slightly introduced with commit
b7471c6da94d30d3deadc55986cc38d1ff57f9ca.

Introduced NMI_DISABLED (-1) which allows to switch the value of NMI_DEFAULT
without breaking the APIC NMI watchdog code (again).

Fixes:
   https://bugzilla.novell.com/show_bug.cgi?id=298084
   http://bugzilla.kernel.org/show_bug.cgi?id=7839
And likely some more nmi_watchdog=0 related issues.

Signed-off-by: Daniel Gollub <dgollub@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 3 deletions

diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index f9fff29e01a9..3d67ae18d762 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -1085,7 +1085,7 @@ static int __init detect_init_APIC (void)
         if (l & MSR_IA32_APICBASE_ENABLE)
                 mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
 
-        if (nmi_watchdog != NMI_NONE)
+        if (nmi_watchdog != NMI_NONE && nmi_watchdog != NMI_DISABLED)
                 nmi_watchdog = NMI_LOCAL_APIC;
 
         printk(KERN_INFO "Found and enabled local APIC!\n");
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index 99beac7f96ce..8c1c965eb2a8 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -77,7 +77,7 @@ static int __init check_nmi_watchdog(void)
         unsigned int *prev_nmi_count;
         int cpu;
 
-        if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DEFAULT))
+        if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED))
                 return 0;
 
         if (!atomic_read(&nmi_active))
@@ -424,7 +424,7 @@ 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) {
+        if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {
                 printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
                 return -EIO;
         }