x86/resctrl: Move default group file creation to mount

The default resource group and its files are created during kernel init
time. Upcoming changes will make some resctrl files optional based on
a mount parameter. If optional files are to be added to the default
group based on the mount option, then each new file needs to be created
separately and call kernfs_activate() again.

Create all files of the default resource group during resctrl mount,
destroyed during unmount, to avoid scattering resctrl file addition
across two separate code flows.

Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Peter Newman <peternewman@google.com>
Reviewed-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20231017002308.134480-6-babu.moger@amd.com

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index d1b5fd70ccbb7dff8c0633eae89a8ebef29d62c9..55da93b5ca53a1fb767727f5272125c7a15eb40d 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -54,6 +54,9 @@ static struct kernfs_node *kn_mondata;
 static struct seq_buf last_cmd_status;
 static char last_cmd_status_buf[512];
 
+static int rdtgroup_setup_root(struct rdt_fs_context *ctx);
+static void rdtgroup_destroy_root(void);
+
 struct dentry *debugfs_resctrl;
 
 void rdt_last_cmd_clear(void)
@@ -2529,10 +2532,14 @@ static int rdt_get_tree(struct fs_context *fc)
                goto out;
        }
 
-       ret = rdt_enable_ctx(ctx);
+       ret = rdtgroup_setup_root(ctx);
        if (ret)
                goto out;
 
+       ret = rdt_enable_ctx(ctx);
+       if (ret)
+               goto out_root;
+
        ret = schemata_list_create();
        if (ret) {
                schemata_list_destroy();
@@ -2541,6 +2548,12 @@ static int rdt_get_tree(struct fs_context *fc)
 
        closid_init();
 
+       ret = rdtgroup_add_files(rdtgroup_default.kn, RFTYPE_CTRL_BASE);
+       if (ret)
+               goto out_schemata_free;
+
+       kernfs_activate(rdtgroup_default.kn);
+
        ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
        if (ret < 0)
                goto out_schemata_free;
@@ -2597,6 +2610,8 @@ out_schemata_free:
        schemata_list_destroy();
 out_ctx:
        rdt_disable_ctx();
+out_root:
+       rdtgroup_destroy_root();
 out:
        rdt_last_cmd_clear();
        mutex_unlock(&rdtgroup_mutex);
@@ -2667,7 +2682,6 @@ static int rdt_init_fs_context(struct fs_context *fc)
        if (!ctx)
                return -ENOMEM;
 
-       ctx->kfc.root = rdt_root;
        ctx->kfc.magic = RDTGROUP_SUPER_MAGIC;
        fc->fs_private = &ctx->kfc;
        fc->ops = &rdt_fs_context_ops;
@@ -2837,6 +2851,7 @@ static void rdt_kill_sb(struct super_block *sb)
        rdt_pseudo_lock_release();
        rdtgroup_default.mode = RDT_MODE_SHAREABLE;
        schemata_list_destroy();
+       rdtgroup_destroy_root();
        static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
        static_branch_disable_cpuslocked(&rdt_mon_enable_key);
        static_branch_disable_cpuslocked(&rdt_enable_key);
@@ -3718,10 +3733,8 @@ static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
        .show_options   = rdtgroup_show_options,
 };
 
-static int __init rdtgroup_setup_root(void)
+static int rdtgroup_setup_root(struct rdt_fs_context *ctx)
 {
-       int ret;
-
        rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
                                      KERNFS_ROOT_CREATE_DEACTIVATED |
                                      KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
@@ -3729,6 +3742,20 @@ static int __init rdtgroup_setup_root(void)
        if (IS_ERR(rdt_root))
                return PTR_ERR(rdt_root);
 
+       ctx->kfc.root = rdt_root;
+       rdtgroup_default.kn = kernfs_root_to_node(rdt_root);
+
+       return 0;
+}
+
+static void rdtgroup_destroy_root(void)
+{
+       kernfs_destroy_root(rdt_root);
+       rdtgroup_default.kn = NULL;
+}
+
+static void __init rdtgroup_setup_default(void)
+{
        mutex_lock(&rdtgroup_mutex);
 
        rdtgroup_default.closid = 0;
@@ -3738,19 +3765,7 @@ static int __init rdtgroup_setup_root(void)
 
        list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);
 
-       ret = rdtgroup_add_files(kernfs_root_to_node(rdt_root), RFTYPE_CTRL_BASE);
-       if (ret) {
-               kernfs_destroy_root(rdt_root);
-               goto out;
-       }
-
-       rdtgroup_default.kn = kernfs_root_to_node(rdt_root);
-       kernfs_activate(rdtgroup_default.kn);
-
-out:
        mutex_unlock(&rdtgroup_mutex);
-
-       return ret;
 }
 
 static void domain_destroy_mon_state(struct rdt_domain *d)
@@ -3872,13 +3887,11 @@ int __init rdtgroup_init(void)
        seq_buf_init(&last_cmd_status, last_cmd_status_buf,
                     sizeof(last_cmd_status_buf));
 
-       ret = rdtgroup_setup_root();
-       if (ret)
-               return ret;
+       rdtgroup_setup_default();
 
        ret = sysfs_create_mount_point(fs_kobj, "resctrl");
        if (ret)
-               goto cleanup_root;
+               return ret;
 
        ret = register_filesystem(&rdt_fs_type);
        if (ret)
@@ -3911,8 +3924,6 @@ int __init rdtgroup_init(void)
 
 cleanup_mountpoint:
        sysfs_remove_mount_point(fs_kobj, "resctrl");
-cleanup_root:
-       kernfs_destroy_root(rdt_root);
 
        return ret;
 }
@@ -3922,5 +3933,4 @@ void __exit rdtgroup_exit(void)
        debugfs_remove_recursive(debugfs_resctrl);
        unregister_filesystem(&rdt_fs_type);
        sysfs_remove_mount_point(fs_kobj, "resctrl");
-       kernfs_destroy_root(rdt_root);
 }