Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change

From	Pan Xinhui <xinhui@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change
Date	2017-02-17 10:40 +0100
Message-ID	<tbNbb-2x5-19@gated-at.bofh.it> (permalink)
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在 2017/2/17 14:05, Michael Ellerman 写道:
> Pan Xinhui <xinhui@linux.vnet.ibm.com> writes:
>> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
>> index 9c0e17c..f6e5c3d 100644
>> --- a/arch/powerpc/xmon/xmon.c
>> +++ b/arch/powerpc/xmon/xmon.c
>> @@ -76,6 +76,7 @@ static int xmon_gate;
>>   #endif /* CONFIG_SMP */
>>
>>   static unsigned long in_xmon __read_mostly = 0;
>> +static int xmon_off = !IS_ENABLED(CONFIG_XMON_DEFAULT);
>
> I think the logic would probably clearer if we invert this to become
> xmon_on.
>
yep, make sense.

>> @@ -3266,16 +3269,16 @@ static int __init setup_xmon_sysrq(void)
>>   __initcall(setup_xmon_sysrq);
>>   #endif /* CONFIG_MAGIC_SYSRQ */
>>
>> -static int __initdata xmon_early, xmon_off;
>> +static int __initdata xmon_early;
>>
>>   static int __init early_parse_xmon(char *p)
>>   {
>>   	if (!p || strncmp(p, "early", 5) == 0) {
>>   		/* just "xmon" is equivalent to "xmon=early" */
>> -		xmon_init(1);
>>   		xmon_early = 1;
>> +		xmon_off = 0;
>>   	} else if (strncmp(p, "on", 2) == 0)
>> -		xmon_init(1);
>> +		xmon_off = 0;
>
> You've just changed the timing of when xmon gets enabled for the above
> two cases, from here which is called very early, to xmon_setup() which
> is called much later in boot.
>
> That effectively disables xmon for most of the boot, which we do not
> want to do.
>
Although it is not often that kernel got stucked during boot. Yes, the behavior changed anyway. Will fix that in v3.

> cheers
>

Thread

[PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2017-02-15 04:00 +0100
  Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> - 2017-02-15 22:30 +0100
  Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change Michael Ellerman <mpe@ellerman.id.au> - 2017-02-16 06:10 +0100
    Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> - 2017-02-16 12:00 +0100
      Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change Pan Xinhui <xinhui@linux.vnet.ibm.com> - 2017-02-16 13:00 +0100
        Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change Michael Ellerman <mpe@ellerman.id.au> - 2017-02-17 07:10 +0100
          Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change Pan Xinhui <xinhui@linux.vnet.ibm.com> - 2017-02-17 10:40 +0100
            Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> - 2017-02-17 13:30 +0100
            Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change Michael Ellerman <mpe@ellerman.id.au> - 2017-02-20 05:50 +0100

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