linux-kernel - Re: [PATCH v2] sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters

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Message-ID: <87d08ol3h6.fsf@nanos.tec.linutronix.de>
Date:   Fri, 03 Apr 2020 22:27:17 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org
Cc:     Ming Lei <ming.lei@...hat.com>, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Luiz Capitulino <lcapitulino@...hat.com>
Subject: Re: [PATCH v2] sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters

Peter Xu <peterx@...hat.com> writes:
> On Thu, Apr 02, 2020 at 10:59:29AM -0400, Peter Xu wrote:
>> -		pr_warn("isolcpus: Error, unknown flag\n");
>> -		return 0;
>> +		/*
>> +		 * Skip unknown sub-parameter and validate that it is not
>> +		 * containing an invalid character.
>> +		 */
>> +		for (par = str, len = 0; *str && *str != ','; str++, len++)

lacks {


>> +			if (!isalpha(*str))
>> +				illegal = true;

lacks }

>> +
>> +		if (illegal) {
>> +			pr_warn("isolcpus: Invalid flag %.*s\n", len, par);
>> +			return 0;
>> +		}
>> +
>> +		pr_info("isolcpus: Skipped unknown flag %.*s\n", len, par);
>> +		str++;
>>  	}
>
> I just noticed this is still problematic if we want to mark this as
> stable, because "managed_irq" violate the "isalpha()" rule already...
> It means even if we apply this patch to the stable trees it'll still
> think managed_irq as illegal and ignore the whole isolcpus=.

		if (!isalpha(*str) && *str != '_')

which is what I told you a couple of days ago already.

Thanks,

        tglx