linux-kernel - Re: [PATCH] drivers/base: cacheinfo: validate device node for all the caches

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Date:	Mon, 23 Feb 2015 15:45:06 +0000
From:	Sudeep Holla <sudeep.holla@....com>
To:	Mark Rutland <mark.rutland@....com>
CC:	Sudeep Holla <sudeep.holla@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] drivers/base: cacheinfo: validate device node for all
 the caches



On 23/02/15 15:14, Mark Rutland wrote:
> On Mon, Feb 16, 2015 at 02:10:16PM +0000, Sudeep Holla wrote:
>> On architectures that depend on DT for obtaining cache hierarcy, we need
>> to validate the device node for all the cache indices, failing to do so
>> might result in wrong information being exposed to the userspace.
>>
>> This is quite possible on initial/incomplete versions of the device
>> trees. In such cases, it's better to bail out if all the required device
>> nodes are not present.
>>
>> This patch adds checks for the validation of device node for all the
>> caches and doesn't initialise the cacheinfo if there's any error.
>>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Reported-by: Mark Rutland <mark.rutland@....com>
>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>> ---
>>   drivers/base/cacheinfo.c | 12 ++++++++++--
>>   1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
>> index 6e64563361f0..7015bf05c828 100644
>> --- a/drivers/base/cacheinfo.c
>> +++ b/drivers/base/cacheinfo.c

[...]

>> @@ -189,8 +195,10 @@ static int detect_cache_attributes(unsigned int cpu)
>>   	 * will be set up here only if they are not populated already
>>   	 */
>>   	ret = cache_shared_cpu_map_setup(cpu);
>> -	if (ret)
>> +	if (ret) {
>> +		pr_err("failed to setup cache hierarcy from DT\n");
>
> It would probably be better if this were something like:
>
> pr_warn("Unable to detect cache hierarcy from DT for CPU %d\n",
> 	cpu);
>

Agreed, will update and send v2.

> Otherwise, this looks sane to me, and it would be nice to have this in
> ASAP so as to avoid exposing erroneous information to userspace. So:
>
> Acked-by: Mark Rutland <mark.rutland@....com>
>

Thanks.

Regards,
Sudeep

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