[PATCH v7 12/49] x86/resctrl: Move rdt_find_domain() to be visible to arch and fs code

James Morse
2025-02-28T20:00:43Z

rdt_find_domain() finds a domain given a resource and a cache-id.
This is used by both the architecture code and the filesystem code.

After the filesystem code moves to live in /fs/, this helper is either
duplicated by all architectures, or needs exposing by the filesystem code.

Add the definition to the global header file. As its now globally visible,
and has only a handful of callers, swap the 'rdt' for 'resctrl'. Move
the function to live with its caller in ctrlmondata.c as the filesystem
code will not have anything corresponding to core.c.

Signed-off-by: James Morse <james.morse@arm.com>

---
Changes since v6:
* Don't inline this helper.
* Moved some words from the discussion into the commit message.

Changes since v5:
* This patch replaced one that split off the 'new entry to insert'
behaviour.
---
arch/x86/kernel/cpu/resctrl/core.c | 38 +++--------------------
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 24 +++++++++++++-
arch/x86/kernel/cpu/resctrl/internal.h | 2 --
include/linux/resctrl.h | 14 +++++++++
4 files changed, 41 insertions(+), 37 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index ce50a7d3230c..26ae43659c6c 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -396,36 +396,6 @@ void rdt_ctrl_update(void *arg)
hw_res->msr_update(m);
}

-/*
- * rdt_find_domain - Search for a domain id in a resource domain list.
- *
- * Search the domain list to find the domain id. If the domain id is
- * found, return the domain. NULL otherwise. If the domain id is not
- * found (and NULL returned) then the first domain with id bigger than
- * the input id can be returned to the caller via @pos.
- */
-struct rdt_domain_hdr *rdt_find_domain(struct list_head *h, int id,
- struct list_head **pos)
-{
- struct rdt_domain_hdr *d;
- struct list_head *l;
-
- list_for_each(l, h) {
- d = list_entry(l, struct rdt_domain_hdr, list);
- /* When id is found, return its domain. */
- if (id == d->id)
- return d;
- /* Stop searching when finding id's position in sorted list. */
- if (id < d->id)
- break;
- }
-
- if (pos)
- *pos = l;
-
- return NULL;
-}
-
static void setup_default_ctrlval(struct rdt_resource *r, u32 *dc)
{
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
@@ -536,7 +506,7 @@ static void domain_add_cpu_ctrl(int cpu, struct rdt_resource *r)
return;
}

- hdr = rdt_find_domain(&r->ctrl_domains, id, &add_pos);
+ hdr = resctrl_find_domain(&r->ctrl_domains, id, &add_pos);
if (hdr) {
if (WARN_ON_ONCE(hdr->type != RESCTRL_CTRL_DOMAIN))
return;
@@ -591,7 +561,7 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
return;
}

- hdr = rdt_find_domain(&r->mon_domains, id, &add_pos);
+ hdr = resctrl_find_domain(&r->mon_domains, id, &add_pos);
if (hdr) {
if (WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN))
return;
@@ -656,7 +626,7 @@ static void domain_remove_cpu_ctrl(int cpu, struct rdt_resource *r)
return;
}

- hdr = rdt_find_domain(&r->ctrl_domains, id, NULL);
+ hdr = resctrl_find_domain(&r->ctrl_domains, id, NULL);
if (!hdr) {
pr_warn("Can't find control domain for id=%d for CPU %d for resource %s\n",
id, cpu, r->name);
@@ -702,7 +672,7 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
return;
}

- hdr = rdt_find_domain(&r->mon_domains, id, NULL);
+ hdr = resctrl_find_domain(&r->mon_domains, id, NULL);
if (!hdr) {
pr_warn("Can't find monitor domain for id=%d for CPU %d for resource %s\n",
id, cpu, r->name);
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 5d87f279085f..763317ea2256 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -610,6 +610,28 @@ int rdtgroup_mba_mbps_event_show(struct kernfs_open_file *of,
return ret;
}

+struct rdt_domain_hdr *resctrl_find_domain(struct list_head *h, int id,
+ struct list_head **pos)
+{
+ struct rdt_domain_hdr *d;
+ struct list_head *l;
+
+ list_for_each(l, h) {
+ d = list_entry(l, struct rdt_domain_hdr, list);
+ /* When id is found, return its domain. */
+ if (id == d->id)
+ return d;
+ /* Stop searching when finding id's position in sorted list. */
+ if (id < d->id)
+ break;
+ }
+
+ if (pos)
+ *pos = l;
+
+ return NULL;
+}
+
void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
cpumask_t *cpumask, int evtid, int first)
@@ -695,7 +717,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
* This file provides data from a single domain. Search
* the resource to find the domain with "domid".
*/
- hdr = rdt_find_domain(&r->mon_domains, domid, NULL);
+ hdr = resctrl_find_domain(&r->mon_domains, domid, NULL);
if (!hdr || WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN)) {
ret = -ENOENT;
goto out;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 8291f1b59981..da73404183da 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -581,8 +581,6 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn);
int rdtgroup_kn_mode_restrict(struct rdtgroup *r, const char *name);
int rdtgroup_kn_mode_restore(struct rdtgroup *r, const char *name,
umode_t mask);
-struct rdt_domain_hdr *rdt_find_domain(struct list_head *h, int id,
- struct list_head **pos);
ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off);
int rdtgroup_schemata_show(struct kernfs_open_file *of,
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index f1979e375da9..93d9a435f035 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -372,6 +372,20 @@ static inline void resctrl_arch_rmid_read_context_check(void)
might_sleep();
}

+/**
+ * resctrl_find_domain() - Search for a domain id in a resource domain list.
+ * @h: The domain list to search.
+ * @id: The domain id to search for.
+ * @pos: A pointer to position in the list id should be inserted.
+ *
+ * Search the domain list to find the domain id. If the domain id is
+ * found, return the domain. NULL otherwise. If the domain id is not
+ * found (and NULL returned) then the first domain with id bigger than
+ * the input id can be returned to the caller via @pos.
+ */
+struct rdt_domain_hdr *resctrl_find_domain(struct list_head *h, int id,
+ struct list_head **pos);
+
/**
* resctrl_arch_reset_rmid() - Reset any private state associated with rmid
* and eventid.
--
2.39.5