[PATCH RFC v4 04/18] fs/resctrl: Add resctrl_is_membw() helper

[Drew Fustini]

Four sites in fs/resctrl distinguish bandwidth resources (MBA, SMBA)
from cache resources by explicit rid match:

  fs/resctrl/ctrlmondata.c parse_line()
  fs/resctrl/rdtgroup.c    rdtgroup_mode_test_exclusive()
  fs/resctrl/rdtgroup.c    rdtgroup_size_show()
  fs/resctrl/rdtgroup.c    rdtgroup_init_alloc()

Replace the open-coded MBA/SMBA tests with a single resctrl_is_membw()
helper keyed on schema_fmt (RESCTRL_SCHEMA_RANGE). No functional change:
every existing RESCTRL_SCHEMA_RANGE resource is MBA or SMBA today.

This isolates fs/resctrl from the addition of further bandwidth resource
types so the four call sites do not have to be updated for each new rid.

Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Drew Fustini <fustini at kernel.org>
---
 fs/resctrl/ctrlmondata.c |  3 +--
 fs/resctrl/internal.h    |  2 ++
 fs/resctrl/rdtgroup.c    | 14 +++++++++-----
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 9a7dfc48cb2e..d9f052700941 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -245,8 +245,7 @@ static int parse_line(char *line, struct resctrl_schema *s,
 	if (WARN_ON_ONCE(!parse_ctrlval))
 		return -EINVAL;
 
-	if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP &&
-	    (r->rid == RDT_RESOURCE_MBA || r->rid == RDT_RESOURCE_SMBA)) {
+	if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP && resctrl_is_membw(r)) {
 		rdt_last_cmd_puts("Cannot pseudo-lock MBA resource\n");
 		return -EINVAL;
 	}
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 1a9b29119f88..76187987b2ee 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -397,6 +397,8 @@ void mbm_handle_overflow(struct work_struct *work);
 
 bool is_mba_sc(struct rdt_resource *r);
 
+bool resctrl_is_membw(struct rdt_resource *r);
+
 void cqm_setup_limbo_handler(struct rdt_l3_mon_domain *dom, unsigned long delay_ms,
 			     int exclude_cpu);
 
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5dfdaa6f9d8f..0f331bf5ce82 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1412,7 +1412,7 @@ static bool rdtgroup_mode_test_exclusive(struct rdtgroup *rdtgrp)
 
 	list_for_each_entry(s, &resctrl_schema_all, list) {
 		r = s->res;
-		if (r->rid == RDT_RESOURCE_MBA || r->rid == RDT_RESOURCE_SMBA)
+		if (resctrl_is_membw(r))
 			continue;
 		has_cache = true;
 		list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
@@ -1555,6 +1555,12 @@ bool is_mba_sc(struct rdt_resource *r)
 	return r->membw.mba_sc;
 }
 
+/* RANGE schema is bandwidth (MBA/SMBA). BITMAP is cache. */
+bool resctrl_is_membw(struct rdt_resource *r)
+{
+	return r->schema_fmt == RESCTRL_SCHEMA_RANGE;
+}
+
 /*
  * rdtgroup_size_show - Display size in bytes of allocated regions
  *
@@ -1616,8 +1622,7 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
 					ctrl = resctrl_arch_get_config(r, d,
 								       closid,
 								       type);
-				if (r->rid == RDT_RESOURCE_MBA ||
-				    r->rid == RDT_RESOURCE_SMBA)
+				if (resctrl_is_membw(r))
 					size = ctrl;
 				else
 					size = rdtgroup_cbm_to_size(r, d, ctrl);
@@ -3648,8 +3653,7 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 
 	list_for_each_entry(s, &resctrl_schema_all, list) {
 		r = s->res;
-		if (r->rid == RDT_RESOURCE_MBA ||
-		    r->rid == RDT_RESOURCE_SMBA) {
+		if (resctrl_is_membw(r)) {
 			rdtgroup_init_mba(r, rdtgrp->closid);
 			if (is_mba_sc(r))
 				continue;

-- 
2.43.0