Re: [PATCH v6 22/22] x86/resctrl: Introduce interface to modify assignment states of the groups

["Moger, Babu" <bmoger@amd.com>]

Hi Reinette,

On 8/23/2024 3:18 PM, Reinette Chatre wrote:
> Hi Babu,
> 
> On 8/21/24 1:11 PM, Moger, Babu wrote:
>> On 8/16/24 17:33, Reinette Chatre wrote:
>>> On 8/6/24 3:00 PM, Babu Moger wrote:
> 
> ...
> 
>>>> +
>>>> +static int rdtgroup_str_to_mon_state(char *flag)
>>>> +{
>>>> +    int i, mon_state = 0;
>>>> +
>>>> +    for (i = 0; i < strlen(flag); i++) {
>>>> +        switch (*(flag + i)) {
>>>> +        case 't':
>>>> +            mon_state |= ASSIGN_TOTAL;
>>>> +            break;
>>>> +        case 'l':
>>>> +            mon_state |= ASSIGN_LOCAL;
>>>> +            break;
>>>> +        case '_':
>>>> +            mon_state = ASSIGN_NONE;
>>>> +            break;
>>>
>>> It looks like this supports flags like "_lt", treating it as assigning
>>> both local and total. I expect this should remove all flags instead?
>>
>> This is a cobination of flags.
>> "_lt"  This will assign both local and total.
>> "lt_"  This with remove both the flags.
>>
>> It seems alright to me. Do you want me to change the bahaviour here?
> 
> This looks like undefined behavior to me. A request to set individual flags
> and also clear all flags looks like a contradiction to me.

Ok. Will address this in v7.

> 
>>
>>
>>>
>>>> +        default:
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    return mon_state;
>>>> +}
>>>
>>> hmmm ... so you removed assigning mon_state to ASSIGN_NONE from default,
>>> but that did not change what this function returns since ASSIGN_NONE 
>>> is 0
>>> and mon_state is initialized to 0. Unknown flags should cause error so
>>> that it is possible to add flags in the future. Above prevents us from
>>> ever adding new flags.
>>
>> May be I am missing something here. How about this?
>>
>> enum {
>>          ASSIGN_NONE = 0,
>>          ASSIGN_TOTAL,
>>          ASSIGN_LOCAL,
>>          ASSIGN_INVALID,
>> };
>>
>>
>> static int rdtgroup_str_to_mon_state(char *flag)
>> {
>>          int i, mon_state = ASSIGN_NONE;
>>
>>          for (i = 0; i < strlen(flag); i++) {
>>                  switch (*(flag + i)) {
>>                  case 't':
>>                          mon_state |= ASSIGN_TOTAL;
>>                          break;
>>                  case 'l':
>>                          mon_state |= ASSIGN_LOCAL;
>>                          break;
>>                  case '_':
>>                          mon_state = ASSIGN_NONE;
>>                          break;
>>                  default:
>>             mon_state = ASSIGN_INVALID;
>>                          goto out_done;
>>                 }
>>          }
>>
>> :out_done:
>>          return mon_state;
>> }
>>
>> Then handle the ASSIGN_INVALID from the caller.  Is that what you think?
> 
> Why not return an error?

Sure.
> 
>>
>>>
>>>> +
>>>> +static struct rdtgroup *rdtgroup_find_grp(enum rdt_group_type rtype,
>>>> char *p_grp, char *c_grp)
>>>
>>> rdtgroup_find_grp() -> rdtgroup_find_grp_by_name()?
>>>
>>>> +{
>>>> +    struct rdtgroup *rdtg, *crg;
>>>> +
>>>> +    if (rtype == RDTCTRL_GROUP && *p_grp == '\0') {
>>>> +        return &rdtgroup_default;
>>>> +    } else if (rtype == RDTCTRL_GROUP) {
>>>> +        list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list)
>>>> +            if (!strcmp(p_grp, rdtg->kn->name))
>>>> +                return rdtg;
>>>> +    } else if (rtype == RDTMON_GROUP) {
>>>> +        list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
>>>> +            if (!strcmp(p_grp, rdtg->kn->name)) {
>>>> +                list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
>>>> +                            mon.crdtgrp_list) {
>>>> +                    if (!strcmp(c_grp, crg->kn->name))
>>>> +                        return crg;
>>>> +                }
>>>> +            }
>>>> +        }
>>>> +    }
>>>> +
>>>> +    return NULL;
>>>> +}
>>>> +
>>>> +static int rdtgroup_process_flags(struct rdt_resource *r,
>>>> +                  enum rdt_group_type rtype,
>>>> +                  char *p_grp, char *c_grp, char *tok)
>>>> +{
>>>> +    int op, mon_state, assign_state, unassign_state;
>>>> +    char *dom_str, *id_str, *op_str;
>>>> +    struct rdt_mon_domain *d;
>>>> +    struct rdtgroup *rdtgrp;
>>>> +    unsigned long dom_id;
>>>> +    int ret, found = 0;
>>>> +
>>>> +    rdtgrp = rdtgroup_find_grp(rtype, p_grp, c_grp);
>>>> +
>>>> +    if (!rdtgrp) {
>>>> +        rdt_last_cmd_puts("Not a valid resctrl group\n");
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +next:
>>>> +    if (!tok || tok[0] == '\0')
>>>> +        return 0;
>>>> +
>>>> +    /* Start processing the strings for each domain */
>>>> +    dom_str = strim(strsep(&tok, ";"));
>>>> +
>>>> +    op_str = strpbrk(dom_str, "=+-");
>>>> +
>>>> +    if (op_str) {
>>>> +        op = *op_str;
>>>> +    } else {
>>>> +        rdt_last_cmd_puts("Missing operation =, +, -, _ character\n");
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +    id_str = strsep(&dom_str, "=+-");
>>>> +
>>>> +    /* Check for domain id '*' which means all domains */
>>>> +    if (id_str && *id_str == '*') {
>>>> +        d = NULL;
>>>> +        goto check_state;
>>>> +    } else if (!id_str || kstrtoul(id_str, 10, &dom_id)) {
>>>> +        rdt_last_cmd_puts("Missing domain id\n");
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +    /* Verify if the dom_id is valid */
>>>> +    list_for_each_entry(d, &r->mon_domains, hdr.list) {
>>>> +        if (d->hdr.id == dom_id) {
>>>> +            found = 1;
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    if (!found) {
>>>> +        rdt_last_cmd_printf("Invalid domain id %ld\n", dom_id);
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +check_state:
>>>> +    mon_state = rdtgroup_str_to_mon_state(dom_str);
>>>
>>> Function should return error and exit here.
>>
>> No. This is case to skip checking for domain when '*' is passed to apply
>> assignment to all the domains.
> 
> Using "*" for a domain still requires valid flags, no?

Yes. Flags will be process as usual.

> 
> Reinette
> 

-- 
- Babu Moger