linux-kernel - Re: [PATCH] x86: cleanups to nmi

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Message-ID: <20080608155649.GC7020@cvg>
Date:	Sun, 8 Jun 2008 19:56:49 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	nm127@...email.hu
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: cleanups to nmi_watchdog variable


| From: Márton Németh <nm127@...email.hu>
| 
| Use NMI_NONE instead of 0. As the symbol NMI_DISABLED equals to -1,
| the nmi_watchdog variable should also be signed.
| 
| Signed-off-by: Márton Németh <nm127@...email.hu>
| ---
| diff -upr linux-2.6.26-rc5.orig/arch/x86/kernel/io_apic_32.c linux-2.6.26-rc5/arch/x86/kernel/io_apic_32.c
| --- linux-2.6.26-rc5.orig/arch/x86/kernel/io_apic_32.c	2008-06-07 12:35:24.000000000 +0200
| +++ linux-2.6.26-rc5/arch/x86/kernel/io_apic_32.c	2008-06-07 12:40:20.000000000 +0200
| @@ -2217,7 +2217,7 @@ static inline void __init check_timer(vo
| 
|  	if (nmi_watchdog == NMI_IO_APIC) {
|  		printk(KERN_WARNING "timer doesn't work through the IO-APIC - disabling NMI Watchdog!\n");
| -		nmi_watchdog = 0;
| +		nmi_watchdog = NMI_NONE;
|  	}
| 
|  	printk(KERN_INFO "...trying to set up timer as Virtual Wire IRQ...");
| diff -upr linux-2.6.26-rc5.orig/arch/x86/kernel/io_apic_64.c linux-2.6.26-rc5/arch/x86/kernel/io_apic_64.c
| --- linux-2.6.26-rc5.orig/arch/x86/kernel/io_apic_64.c	2008-06-05 18:39:49.000000000 +0200
| +++ linux-2.6.26-rc5/arch/x86/kernel/io_apic_64.c	2008-06-07 12:37:01.000000000 +0200
| @@ -1735,7 +1735,7 @@ static inline void __init check_timer(vo
| 
|  	if (nmi_watchdog == NMI_IO_APIC) {
|  		printk(KERN_WARNING "timer doesn't work through the IO-APIC - disabling NMI Watchdog!\n");
| -		nmi_watchdog = 0;
| +		nmi_watchdog = NMI_NONE;
|  	}
| 
|  	apic_printk(APIC_VERBOSE, KERN_INFO "...trying to set up timer as Virtual Wire IRQ...");
| diff -upr linux-2.6.26-rc5.orig/arch/x86/kernel/nmi_32.c linux-2.6.26-rc5/arch/x86/kernel/nmi_32.c
| --- linux-2.6.26-rc5.orig/arch/x86/kernel/nmi_32.c	2008-06-05 18:39:49.000000000 +0200
| +++ linux-2.6.26-rc5/arch/x86/kernel/nmi_32.c	2008-06-07 11:19:55.000000000 +0200
| @@ -43,7 +43,7 @@ static cpumask_t backtrace_mask = CPU_MA
|   */
|  atomic_t nmi_active = ATOMIC_INIT(0);		/* oprofile uses this */
| 
| -unsigned int nmi_watchdog = NMI_DEFAULT;
| +int nmi_watchdog = NMI_DEFAULT;
|  static unsigned int nmi_hz = HZ;
| 
|  static DEFINE_PER_CPU(short, wd_enabled);
| diff -upr linux-2.6.26-rc5.orig/arch/x86/kernel/nmi_64.c linux-2.6.26-rc5/arch/x86/kernel/nmi_64.c
| --- linux-2.6.26-rc5.orig/arch/x86/kernel/nmi_64.c	2008-06-05 18:39:49.000000000 +0200
| +++ linux-2.6.26-rc5/arch/x86/kernel/nmi_64.c	2008-06-07 11:20:00.000000000 +0200
| @@ -43,7 +43,7 @@ static cpumask_t backtrace_mask = CPU_MA
|  atomic_t nmi_active = ATOMIC_INIT(0);		/* oprofile uses this */
|  static int panic_on_timeout;
| 
| -unsigned int nmi_watchdog = NMI_DEFAULT;
| +int nmi_watchdog = NMI_DEFAULT;
|  static unsigned int nmi_hz = HZ;
| 
|  static DEFINE_PER_CPU(short, wd_enabled);
| diff -upr linux-2.6.26-rc5.orig/include/asm-x86/nmi.h linux-2.6.26-rc5/include/asm-x86/nmi.h
| --- linux-2.6.26-rc5.orig/include/asm-x86/nmi.h	2008-06-05 18:40:12.000000000 +0200
| +++ linux-2.6.26-rc5/include/asm-x86/nmi.h	2008-06-07 11:21:20.000000000 +0200
| @@ -61,7 +61,7 @@ extern void enable_timer_nmi_watchdog(vo
|  extern int nmi_watchdog_tick(struct pt_regs *regs, unsigned reason);
| 
|  extern atomic_t nmi_active;
| -extern unsigned int nmi_watchdog;
| +extern int nmi_watchdog;
|  #define NMI_DISABLED    -1
|  #define NMI_NONE	0
|  #define NMI_IO_APIC	1
| 

We should leave nmi_watchdog as unsigned. The only snippet which
could be reviewed as controversy point  - is touch_nmi_watchdog()
where we just test nmi_watchdog for being greater than 0. Actually
there NMI_NONE should be used instead. But frankly some additional
simplification is needed.

		- Cyrill -
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