On Fri, 15 Sep 2023, Babu Moger wrote:
> 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.
>
> Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Reviewed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 58 +++++++++++++++-----------
> 1 file changed, 34 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 3ea874c80c22..a34657f0bd0c 100644
> --- 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)
> @@ -2511,10 +2514,14 @@ 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();
> @@ -2523,6 +2530,12 @@ 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;
> @@ -2579,6 +2592,8 @@ static int rdt_get_tree(struct fs_context *fc)
> schemata_list_destroy();
> out_ctx:
> rdt_disable_ctx();
> +out_root:
> + rdtgroup_destroy_root();
> out:
> rdt_last_cmd_clear();
> mutex_unlock(&rdtgroup_mutex);
> @@ -2649,7 +2664,6 @@ 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;
> @@ -2819,6 +2833,7 @@ 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);
> @@ -3700,10 +3715,8 @@ 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,
> @@ -3711,6 +3724,20 @@ 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;
> @@ -3720,19 +3747,7 @@ 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)
> @@ -3854,13 +3869,11 @@ 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)
> @@ -3893,8 +3906,6 @@ int __init rdtgroup_init(void)
>
> cleanup_mountpoint:
> sysfs_remove_mount_point(fs_kobj, "resctrl");
> -cleanup_root:
> - kernfs_destroy_root(rdt_root);
>
> return ret;
> }
> @@ -3904,5 +3915,4 @@ 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);
> }
>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
--
i.
