lkml.org 
[lkml]   [2018]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/3] x86/intel_rdt: CBM overlap should also check for overlap with CDP peer
From
Date
Hi Thomas,

On 10/3/2018 12:43 PM, Thomas Gleixner wrote:
> On Wed, 3 Oct 2018, Reinette Chatre wrote:
>> On 10/3/2018 12:02 AM, Thomas Gleixner wrote:
>>>> +{
>>>> + struct rdt_resource *r_cdp;
>>>> + struct rdt_domain *d_cdp;
>>>> + bool ret;
>>>> +
>>>> + ret = _rdtgroup_cbm_overlaps(r, d, _cbm, closid, exclusive);
>>>> + if (ret)
>>>> + return ret;
>>>
>>> if (__rdtgroup_cbm_overlaps(r, d, _cbm, closid, exclusive))
>>> return true;
>>>
>>>> +
>>>> + if (rdt_cdp_peer_get(r, d, &r_cdp, &d_cdp) == 0)
>>>> + return _rdtgroup_cbm_overlaps(r_cdp, d_cdp, _cbm,
>>>> + closid, exclusive);
>>>
>>> if (rdt_cdp_peer_get(r, d, &r_cdp, &d_cdp) < 0)
>>> return false;
>>>
>>> return __rdtgroup_cbm_overlaps(r_cpd, d_cdp, _cbm, closid, exclusive);
>>>
>>> Makes the whole thing more obvious.
>>
>> I think a different change is needed to support the request from your
>> review of the first patch to propagate that unthinkable error where only
>> one of the CDP peers could have an rdt_domain associated with it.
>>
>> In the above that error in question from rdt_cdp_peer_get() will be lost.
>>
>> I could do the following in support of propagating that error (note that
>> in support of the code below __rdtgroup_cbm_overlaps() also changes to
>> return int instead of bool):
>>
>> int rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_domain *d,
>> u32 cbm, int closid, bool exclusive)
>> {
>> struct rdt_resource *r_cdp;
>> struct rdt_domain *d_cdp;
>> int ret;
>>
>> if (__rdtgroup_cbm_overlaps(r, d, cbm, closid, exclusive))
>> return 1;
>>
>> ret = rdt_cdp_peer_get(r, d, &r_cdp, &d_cdp);
>> if (ret == -ENOENT) {
>> return 0;
>> } else if (ret == -EINVAL) {
>> rdt_last_cmd_puts("Error finding CDP peer\n");
>> return ret;
>> } else {
>> return __rdtgroup_cbm_overlaps(r_cdp, d_cdp, cbm,
>> closid, exclusive);
>> }
>>
>> return -EINVAL;
>> }
>>
>> With the above change in rdtgroup_cbm_overlaps() the call sites then
>> change to for example:
>>
>> ret = rdtgroup_cbm_overlaps(r, d, cbm_val, rdtgrp->closid, true);
>> if (ret < 0) {
>> /* last_cmd_status already populated with error */
>> return -EINVAL;
>> } else if (ret == 1) {
>> rdt_last_cmd_puts("overlaps with exclusive group\n");
>> return -EINVAL;
>> }
>> /* fall through when no overlap detected */
>>
>> Would this be acceptable?
>
> We really have to think about that whether it's worth it. Looking at the
> resulting code I doubt it. Then I'd rather prefer the warnon and the
> simpler code. But either way works for me.

Thank you very much. I'll resubmit with the changes you prefer.

Reinette

\
 
 \ /
  Last update: 2018-10-03 21:53    [W:0.028 / U:0.336 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site