x86/resctrl: Move monitor exit work to a resctrl exit call

rdt_put_mon_l3_config() is called via the architecture's resctrl_arch_exit()
call, and appears to free the rmid_ptrs[] and closid_num_dirty_rmid[] arrays.
In reality this code is marked __exit, and is removed by the linker as resctrl
can't be built as a module.

To separate the filesystem and architecture parts of resctrl, this free()ing
work needs to be triggered by the filesystem, as these structures belong to
the filesystem code.

Rename rdt_put_mon_l3_config() to resctrl_mon_resource_exit() and call it from
resctrl_exit(). The kfree() is currently dependent on r->mon_capable.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-16-james.morse@arm.com

Author: James Morse

arch/x86/kernel/cpu/resctrl/core.c

@@ -1074,14 +1074,9 @@ late_initcall(resctrl_arch_late_init);
 
 static void __exit resctrl_arch_exit(void)
 {
-	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
-
 	cpuhp_remove_state(rdt_online);
 
 	resctrl_exit();
-
-	if (r->mon_capable)
-		rdt_put_mon_l3_config();
 }
 
 __exitcall(resctrl_arch_exit);

arch/x86/kernel/cpu/resctrl/internal.h

@@ -586,7 +586,7 @@ void closid_free(int closid);
 int alloc_rmid(u32 closid);
 void free_rmid(u32 closid, u32 rmid);
 int rdt_get_mon_l3_config(struct rdt_resource *r);
-void __exit rdt_put_mon_l3_config(void);
+void __exit resctrl_mon_resource_exit(void);
 bool __init rdt_cpu_has(int flag);
 void mon_event_count(void *info);
 int rdtgroup_mondata_show(struct seq_file *m, void *arg);

arch/x86/kernel/cpu/resctrl/monitor.c

@@ -1040,10 +1040,13 @@ static int dom_data_init(struct rdt_resource *r)
 	return err;
 }
 
-static void __exit dom_data_exit(void)
+static void __exit dom_data_exit(struct rdt_resource *r)
 {
 	mutex_lock(&rdtgroup_mutex);
 
+	if (!r->mon_capable)
+		goto out_unlock;
+
 	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
 		kfree(closid_num_dirty_rmid);
 		closid_num_dirty_rmid = NULL;
@@ -1052,6 +1055,7 @@ static void __exit dom_data_exit(void)
 	kfree(rmid_ptrs);
 	rmid_ptrs = NULL;
 
+out_unlock:
 	mutex_unlock(&rdtgroup_mutex);
 }
 
@@ -1237,9 +1241,11 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	return 0;
 }
 
-void __exit rdt_put_mon_l3_config(void)
+void __exit resctrl_mon_resource_exit(void)
 {
-	dom_data_exit();
+	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+
+	dom_data_exit(r);
 }
 
 void __init intel_rdt_mbm_apply_quirk(void)

arch/x86/kernel/cpu/resctrl/rdtgroup.c

@@ -4296,4 +4296,6 @@ void __exit resctrl_exit(void)
 	debugfs_remove_recursive(debugfs_resctrl);
 	unregister_filesystem(&rdt_fs_type);
 	sysfs_remove_mount_point(fs_kobj, "resctrl");
+
+	resctrl_mon_resource_exit();
 }