get_{mon,ctrl}_domain_from_cpu() are handy helpers that both the arch
code and resctrl need to use. Rename them to have a resctrl_ prefix
and move them to a header file.

Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
---
 arch/x86/kernel/cpu/resctrl/core.c     | 30 ---------------------
 arch/x86/kernel/cpu/resctrl/internal.h |  2 --
 arch/x86/kernel/cpu/resctrl/monitor.c  |  2 +-
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |  2 +-
 include/linux/resctrl.h                | 37 ++++++++++++++++++++++++++
 5 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 0da7314195af..f484726a2588 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -349,36 +349,6 @@ static void cat_wrmsr(struct msr_param *m)
 		wrmsrl(hw_res->msr_base + i, hw_dom->ctrl_val[i]);
 }
 
-struct rdt_ctrl_domain *get_ctrl_domain_from_cpu(int cpu, struct rdt_resource *r)
-{
-	struct rdt_ctrl_domain *d;
-
-	lockdep_assert_cpus_held();
-
-	list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
-		/* Find the domain that contains this CPU */
-		if (cpumask_test_cpu(cpu, &d->hdr.cpu_mask))
-			return d;
-	}
-
-	return NULL;
-}
-
-struct rdt_mon_domain *get_mon_domain_from_cpu(int cpu, struct rdt_resource *r)
-{
-	struct rdt_mon_domain *d;
-
-	lockdep_assert_cpus_held();
-
-	list_for_each_entry(d, &r->mon_domains, hdr.list) {
-		/* Find the domain that contains this CPU */
-		if (cpumask_test_cpu(cpu, &d->hdr.cpu_mask))
-			return d;
-	}
-
-	return NULL;
-}
-
 u32 resctrl_arch_get_num_closid(struct rdt_resource *r)
 {
 	return resctrl_to_arch_res(r)->num_closid;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 30de95e59129..e939a0a28a49 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -468,8 +468,6 @@ unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r, struct rdt_ctrl_domain
 				  unsigned long cbm);
 enum rdtgrp_mode rdtgroup_mode_by_closid(int closid);
 int rdtgroup_tasks_assigned(struct rdtgroup *r);
-struct rdt_ctrl_domain *get_ctrl_domain_from_cpu(int cpu, struct rdt_resource *r);
-struct rdt_mon_domain *get_mon_domain_from_cpu(int cpu, struct rdt_resource *r);
 int closids_supported(void);
 void closid_free(int closid);
 int alloc_rmid(u32 closid);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 175fd7dbf34f..39c450624ed0 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -767,7 +767,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
 	idx = resctrl_arch_rmid_idx_encode(closid, rmid);
 	pmbm_data = &dom_mbm->mbm_local[idx];
 
-	dom_mba = get_ctrl_domain_from_cpu(smp_processor_id(), r_mba);
+	dom_mba = resctrl_get_ctrl_domain_from_cpu(smp_processor_id(), r_mba);
 	if (!dom_mba) {
 		pr_warn_once("Failure to get domain for MBA update\n");
 		return;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 596f5f087834..ee9c3e4ee889 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -4235,7 +4235,7 @@ void resctrl_offline_cpu(unsigned int cpu)
 	if (!l3->mon_capable)
 		goto out_unlock;
 
-	d = get_mon_domain_from_cpu(cpu, l3);
+	d = resctrl_get_mon_domain_from_cpu(cpu, l3);
 	if (d) {
 		if (resctrl_is_mbm_enabled() && cpu == d->mbm_work_cpu) {
 			cancel_delayed_work(&d->mbm_over);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 653d7cf41e64..bbce79190b13 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -3,6 +3,7 @@
 #define _RESCTRL_H
 
 #include <linux/cacheinfo.h>
+#include <linux/cpu.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/pid.h>
@@ -397,6 +398,42 @@ static inline u32 resctrl_get_config_index(u32 closid,
 	}
 }
 
+/*
+ * Caller must hold the cpuhp read lock to prevent the struct rdt_domain being
+ * freed.
+ */
+static inline struct rdt_ctrl_domain *
+resctrl_get_ctrl_domain_from_cpu(int cpu, struct rdt_resource *r)
+{
+	struct rdt_ctrl_domain *d;
+
+	lockdep_assert_cpus_held();
+
+	list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
+		/* Find the domain that contains this CPU */
+		if (cpumask_test_cpu(cpu, &d->hdr.cpu_mask))
+			return d;
+	}
+
+	return NULL;
+}
+
+static inline struct rdt_mon_domain *
+resctrl_get_mon_domain_from_cpu(int cpu, struct rdt_resource *r)
+{
+	struct rdt_mon_domain *d;
+
+	lockdep_assert_cpus_held();
+
+	list_for_each_entry(d, &r->mon_domains, hdr.list) {
+		/* Find the domain that contains this CPU */
+		if (cpumask_test_cpu(cpu, &d->hdr.cpu_mask))
+			return d;
+	}
+
+	return NULL;
+}
+
 /*
  * Update the ctrl_val and apply this config right now.
  * Must be called on one of the domain's CPUs.
-- 
2.39.2

Hi James,

On 10/4/24 11:03 AM, James Morse wrote:
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 653d7cf41e64..bbce79190b13 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -3,6 +3,7 @@
>  #define _RESCTRL_H
>  
>  #include <linux/cacheinfo.h>
> +#include <linux/cpu.h>
>  #include <linux/kernel.h>
>  #include <linux/list.h>
>  #include <linux/pid.h>
> @@ -397,6 +398,42 @@ static inline u32 resctrl_get_config_index(u32 closid,
>  	}
>  }
>  
> +/*
> + * Caller must hold the cpuhp read lock to prevent the struct rdt_domain being
> + * freed.

"prevent the struct rdt_domain from being freed."?

Reinette