Re: [RFC 09/12] fs/resctrl: Extend schemata write for priority partition control

From: Fenghua Yu
Date: Thu Aug 17 2023 - 13:28:43 EST


Hi, Amit,

On 8/15/23 08:27, Amit Singh Tomar wrote:
Currently, Users can pass the configurations for CPBM, and MBA through
schemata file. For instance, CPBM can be passed using:

echo L3:0=ffff > schemata

This change allows, users to pass a new configuration for downstream
priority along with CPBM. For instance, dspri value of "0xa" can be
passed as:

echo L3:0=ffff,a > schemata

Signed-off-by: Amit Singh Tomar <amitsinght@xxxxxxxxxxx>
---
fs/resctrl/ctrlmondata.c | 92 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)

diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index ffeb68270968..b444adee2002 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -30,6 +30,74 @@ typedef int (ctrlval_parser_t)(struct rdt_parse_data *data,
struct resctrl_schema *s,
struct rdt_domain *d);
+static bool dspri_validate(char *buf, unsigned long *data, struct rdt_resource *r)
+{
+
+ char *dup_buf, *dspri_token;
+ unsigned long dspri_val;
+ bool success = true;
+ int ret;
+
+ dup_buf = kstrdup(buf, GFP_KERNEL);
+ if (!dup_buf) {
+ rdt_last_cmd_printf("Failed to allocate buffer %s\n",
+ __func__);
+ success = false;
+ goto out;
+ }
+
+ strsep(&dup_buf, ",");
+ if (!dup_buf) {
+ rdt_last_cmd_printf("Unable to find priority value token %s\n",
+ __func__);
+ success = false;
+ goto out;
+ }
+
+ dspri_token = strsep(&dup_buf, ",");
+ ret = kstrtoul(dspri_token, 16, &dspri_val);
+ if (ret) {
+ rdt_last_cmd_printf("Non-hex character in the mask %s\n", buf);
+ success = false;
+ goto out;
+ }
+
+ if (dspri_val > r->dspri_default_ctrl) {
+ rdt_last_cmd_printf("dspri value %ld out of range [%d-%d]\n", dspri_val,
+ 0, r->dspri_default_ctrl);
+ success = false;
+ goto out;
+ }
+
+ *data = dspri_val;
+
+out:
+ kfree(dup_buf);
+ return success;
+}
+
+static int parse_dspri(struct rdt_parse_data *data, struct resctrl_schema *s,
+ struct rdt_domain *d)
+{
+ struct resctrl_staged_config *cfg;
+ struct rdt_resource *r = s->res;
+ unsigned long pri_val;
+
+ cfg = &d->staged_config[s->conf_type];
+ if (cfg->have_new_ctrl) {
+ rdt_last_cmd_printf("Duplicate domain %d\n", d->id);
+ return -EINVAL;
+ }
+
+ if (!dspri_validate(data->buf, &pri_val, r))
+ return -EINVAL;
+
+ cfg->new_ctrl = pri_val;
+ cfg->have_new_ctrl = true;
+
+ return 0;
+}
+
/*
* Check whether MBA bandwidth percentage value is correct. The value is
* checked against the minimum and max bandwidth values specified by the
@@ -293,6 +361,8 @@ static int rdtgroup_parse_resource(char *resname, char *tok,
ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
+ char *dup_buf = kstrdup(buf, GFP_KERNEL);
+ struct rdt_parse_data data;
struct resctrl_schema *s;
struct rdtgroup *rdtgrp;
struct rdt_domain *dom;
@@ -354,10 +424,32 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
if (is_mba_sc(r))
continue;
+ if (r->priority_cap)
+ r->dspri_store = false;
+
if (!strcmp(resname, s->name)) {
ret = resctrl_arch_update_domains(r, rdtgrp->closid);
if (ret)
goto out;
+
+ if (r->priority_cap) {
+ r->dspri_store = true;
+ list_for_each_entry(dom, &r->domains, list) {
+ ctrlval_parser_t *parse_ctrlval = &parse_dspri;
+ char *dom_data = NULL;
+
+ dom_data = strsep(&dup_buf, ";");
+ dom_data = strim(dom_data);
+ data.buf = dom_data;
+ data.rdtgrp = rdtgrp;
+ if (parse_ctrlval(&data, s, dom))

Can this parse be called within parse_line()? So parsing and validation are before real write. If any parsing error, no write. Otherwise, partial write or roll back may happen.

+ return -EINVAL;
+ }
+
+ ret = resctrl_arch_update_domains(r, rdtgrp->closid);
+ if (ret)
+ goto out;

r->dspri_store = false here?

+ }
}
}

Thanks.

-Fenghua