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

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Date:	Sun, 8 Jun 2008 20:31:33 +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

[=?ISO-8859-1?Q?N=E9meth_M=E1rton_ - Sun, Jun 08, 2008 at 06:23:38PM +0200]
| Cyrill Gorcunov wrote:
| > | 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.
| 
| Don't forget that the NMI_DEFAULT symbol in include/asm-x86/nmi.h also equals to
| NMI_DISABLED, which is -1.
| 
| 	Márton Németh
| 

yes, i know

		- Cyrill -
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