Hi Reinette,
Thanks for the review of series.
On 9/2/25 21:41, Reinette Chatre wrote:
> Hi Babu,
>
> On 8/14/25 7:25 PM, Babu Moger wrote:
>
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 25fec9bf2d61..9201fedd2796 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -1029,6 +1029,125 @@ int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq, void *v
>> return ret;
>> }
>>
>> +static int resctrl_parse_mem_transactions(char *tok, u32 *val)
>> +{
>> + u32 temp_val = 0;
>> + char *evt_str;
>> + bool found;
>> + int i;
>> +
>> +next_config:
>> + if (!tok || tok[0] == '\0') {
>> + *val = temp_val;
>> + return 0;
>> + }
>
> Looks like resctrl_parse_mem_transactions() can return "success" with a parsed
> return value of "0" (*val = 0) ... (follow-up comment in event_filter_write()).
Yes. *val=0 is a valid value.
>
>> +
>> + /* Start processing the strings for each memory transaction type */
>> + evt_str = strim(strsep(&tok, ","));
>> + found = false;
>> + for (i = 0; i < NUM_MBM_TRANSACTIONS; i++) {
>> + if (!strcmp(mbm_transactions[i].name, evt_str)) {
>> + temp_val |= mbm_transactions[i].val;
>> + found = true;
>> + break;
>> + }
>> + }
>> +
>> + if (!found) {
>> + rdt_last_cmd_printf("Invalid memory transaction type %s\n", evt_str);
>> + return -EINVAL;
>> + }
>> +
>> + goto next_config;
>> +}
>> +
>> +/*
>> + * rdtgroup_update_cntr_event - Update the counter assignments for the event
>> + * in a group.
>> + * @r: Resource to which update needs to be done.
>> + * @rdtgrp: Resctrl group.
>> + * @evtid: MBM monitor event.
>> + */
>> +static void rdtgroup_update_cntr_event(struct rdt_resource *r, struct rdtgroup *rdtgrp,
>> + enum resctrl_event_id evtid)
>> +{
>> + struct rdt_mon_domain *d;
>> + struct mbm_state *m;
>> + int cntr_id;
>> +
>> + list_for_each_entry(d, &r->mon_domains, hdr.list) {
>> + cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
>> + if (cntr_id >= 0) {
>> + resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
>> + rdtgrp->closid, cntr_id, true);
>> + m = get_mbm_state(d, rdtgrp->closid, rdtgrp->mon.rmid, evtid);
>> + if (m)
>> + memset(m, 0, sizeof(*m));
>
> This looks like open code of rdtgroup_assign_cntr()?
Will call rdtgroup_assign_cntr() directly here.
>
>> + }
>> + }
>> +}
>> +
>
> ...
>
>> +
>> +ssize_t event_filter_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
>> + loff_t off)
>> +{
>> + struct mon_evt *mevt = rdt_kn_parent_priv(of->kn);
>> + struct rdt_resource *r;
>> + u32 evt_cfg = 0;
>> + int ret = 0;
>> +
>> + /* Valid input requires a trailing newline */
>> + if (nbytes == 0 || buf[nbytes - 1] != '\n')
>> + return -EINVAL;
>> +
>> + buf[nbytes - 1] = '\0';
>> +
>> + cpus_read_lock();
>> + mutex_lock(&rdtgroup_mutex);
>> +
>> + rdt_last_cmd_clear();
>> +
>> + r = resctrl_arch_get_resource(mevt->rid);
>> + if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
>> + rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
>> + ret = -EINVAL;
>> + goto out_unlock;
>> + }
>> +
>> + ret = resctrl_parse_mem_transactions(buf, &evt_cfg);
>> + if (!ret && mevt->evt_cfg != evt_cfg) {
>
> ... is evt_cfg of 0 (a) a valid value (that will not cause hardware to fault) and
> (b) a reasonable value to allow?
>
The value evt_cfg = 0 is valid and permitted for both ABMC and BMEC. I
have confirmed here through verification and testing. In that case, the
event counter will not be monitoring anything.
--
Thanks
Babu Moger
