x86: nmi - fix incorrect NMI watchdog used by default

The commit

	commit 4b82b277707a39b97271439c475f186f63ec4692
	Author: Cyrill Gorcunov <gorcunov@gmail.com>
	Date:   Sat May 24 19:36:35 2008 +0400

set nmi_watchdog to NMI_IO_APIC as by default. This causes hangs on some
machines with buggy watchdogs. Fix it - i.e. restore old behaviour.

Thanks to Sitsofe Wheeler and Adrian Bunk for catching the problem
and Maciej W. Rozycki for explanation what is going on there.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
CC: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 7 deletions

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 69a839fc1eb0..3671a9f3564b 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -84,20 +84,15 @@ static inline unsigned int get_timer_irqs(int cpu)
 #endif
 }
 
+#ifdef CONFIG_X86_64
 /* Run after command line and cpu_init init, but before all other checks */
 void nmi_watchdog_default(void)
 {
         if (nmi_watchdog != NMI_DEFAULT)
                 return;
-#ifdef CONFIG_X86_64
         nmi_watchdog = NMI_NONE;
-#else
-        if (lapic_watchdog_ok())
-                nmi_watchdog = NMI_LOCAL_APIC;
-        else
-                nmi_watchdog = NMI_IO_APIC;
-#endif
 }
+#endif
 
 #ifdef CONFIG_SMP
 /*
@@ -488,8 +483,15 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
                 return -EIO;
         }
 
+#ifdef CONFIG_X86_64
         /* if nmi_watchdog is not set yet, then set it */
         nmi_watchdog_default();
+#else
+        if (lapic_watchdog_ok())
+                nmi_watchdog = NMI_LOCAL_APIC;
+        else
+                nmi_watchdog = NMI_IO_APIC;
+#endif
 
         if (nmi_watchdog == NMI_LOCAL_APIC) {
                 if (nmi_watchdog_enabled)