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>

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 69a839fc1eb0d36f2abc5d838de0558c39fb754d..3671a9f3564b5a41a78595a7419b3c99b61b0e00 100644 (file)
--- 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)

diff --git a/include/asm-x86/nmi.h b/include/asm-x86/nmi.h
index 1e8f34d7ab68d528d0724f7494fb37f8343a2b46..6f4d44fc051f1715290131f300204dca15591f20 100644 (file)
--- a/include/asm-x86/nmi.h
+++ b/include/asm-x86/nmi.h
@@ -38,9 +38,11 @@ static inline void unset_nmi_pm_callback(struct pm_dev *dev)
 
 #ifdef CONFIG_X86_64
 extern void default_do_nmi(struct pt_regs *);
+extern void nmi_watchdog_default(void);
+#else
+#define nmi_watchdog_default(void) do {} while (0)
 #endif
 
-extern void nmi_watchdog_default(void);
 extern void die_nmi(char *str, struct pt_regs *regs, int do_panic);
 extern int check_nmi_watchdog(void);
 extern int nmi_watchdog_enabled;