linux-kernel - Re: [PATCH 6/9] x86/intel_rdt: Add support for cache bit mask management

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Date:	Thu, 30 Jul 2015 10:54:13 -0700 (PDT)
From:	Vikas Shivappa <vikas.shivappa@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	linux-kernel@...r.kernel.org, vikas.shivappa@...el.com,
	x86@...nel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...nel.org, tj@...nel.org, matt.fleming@...el.com,
	will.auld@...el.com, glenn.p.williamson@...el.com,
	kanaka.d.juvva@...el.com
Subject: Re: [PATCH 6/9] x86/intel_rdt: Add support for cache bit mask
 management



On Tue, 28 Jul 2015, Peter Zijlstra wrote:

> On Wed, Jul 01, 2015 at 03:21:07PM -0700, Vikas Shivappa wrote:
>> +static int cbm_validate(struct intel_rdt *ir, unsigned long cbmvalue)
>> +{
>> +	struct cgroup_subsys_state *css;
>> +	struct intel_rdt *par, *c;
>> +	unsigned long *cbm_tmp;
>> +	int err = 0;
>> +
>> +	if (!cbm_is_contiguous(cbmvalue)) {
>> +		pr_err("bitmask should have >= 1 bit and be contiguous\n");
>> +		err = -EINVAL;
>> +		goto out_err;
>> +	}
>
>> +static struct cftype rdt_files[] = {
>> +	{
>> +		.name		= "l3_cache_mask",
>> +		.seq_show	= intel_cache_alloc_cbm_read,
>> +		.write_u64	= intel_cache_alloc_cbm_write,
>> +		.mode		= 0666,
>
> So this file is world writable? How is the above pr_err() not a DoS ?

Will fix. the mode can be default and can remove pr_err 
Thanks,
Vikas

>
>> +	},
>> +	{ }	/* terminate */
>> +};
>
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