Hi Babu,
On 6/1/2023 12:02 PM, Babu Moger wrote:
> Currently, the resctrl default control group is created during kernel
> init time and rest of the files are added during mount. If the new
Please drop the word "Currently"
> files are to be added to the default group during the mount then it
> has to be done separately again.
>
> This can avoided if all the files are created during the mount and
> destroyed during the umount. Move the default group creation in
"creation in" -> "creation to"?
> rdt_get_tree and removal in rdt_kill_sb.
I think it would be simpler if this patch is moved earlier in series
then patch 8 can more easily be squashed where appropriate.
>
> Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 59 ++++++++++++++++----------------
> 1 file changed, 30 insertions(+), 29 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 2f5cdc638607..e03cb01c4742 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -57,6 +57,7 @@ static char last_cmd_status_buf[512];
> struct dentry *debugfs_resctrl;
>
> static bool resctrl_debug;
> +static int rdtgroup_setup_root(void);
>
> void rdt_last_cmd_clear(void)
> {
> @@ -2515,13 +2516,6 @@ static int rdt_get_tree(struct fs_context *fc)
>
> cpus_read_lock();
> mutex_lock(&rdtgroup_mutex);
> - /*
> - * resctrl file system can only be mounted once.
> - */
> - if (static_branch_unlikely(&rdt_enable_key)) {
> - ret = -EBUSY;
> - goto out;
> - }
>
This change is unexpected.
> ret = rdt_enable_ctx(ctx);
> if (ret < 0)
> @@ -2535,9 +2529,15 @@ 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;
> + goto out_default;
>
> if (rdt_mon_capable) {
> ret = mongroup_create_dir(rdtgroup_default.kn,
> @@ -2587,6 +2587,8 @@ static int rdt_get_tree(struct fs_context *fc)
> kernfs_remove(kn_mongrp);
> out_info:
> kernfs_remove(kn_info);
> +out_default:
> + kernfs_remove(rdtgroup_default.kn);
> out_schemata_free:
> schemata_list_destroy();
> out_mba:
> @@ -2664,10 +2666,23 @@ static const struct fs_context_operations rdt_fs_context_ops = {
> static int rdt_init_fs_context(struct fs_context *fc)
> {
> struct rdt_fs_context *ctx;
> + int ret;
> +
> + /*
> + * resctrl file system can only be mounted once.
> + */
> + if (static_branch_unlikely(&rdt_enable_key))
> + return -EBUSY;
> +
> + ret = rdtgroup_setup_root();
> + if (ret)
> + return ret;
>
Why was it necessary to move this code?
> ctx = kzalloc(sizeof(struct rdt_fs_context), GFP_KERNEL);
> - if (!ctx)
> + if (!ctx) {
> + kernfs_destroy_root(rdt_root);
> return -ENOMEM;
> + }
>
> ctx->kfc.root = rdt_root;
> ctx->kfc.magic = RDTGROUP_SUPER_MAGIC;
> @@ -2845,6 +2860,9 @@ static void rdt_kill_sb(struct super_block *sb)
> static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
> static_branch_disable_cpuslocked(&rdt_mon_enable_key);
> static_branch_disable_cpuslocked(&rdt_enable_key);
> + /* Remove the default group and cleanup the root */
> + list_del(&rdtgroup_default.rdtgroup_list);
> + kernfs_destroy_root(rdt_root);
Why not just add kernfs_remove(rdtgroup_default.kn) to rmdir_all_sub()?
> kernfs_kill_sb(sb);
> mutex_unlock(&rdtgroup_mutex);
> cpus_read_unlock();
> @@ -3598,10 +3616,8 @@ 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(void)
> {
> - int ret;
> -
> rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
> KERNFS_ROOT_CREATE_DEACTIVATED |
> KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
> @@ -3618,19 +3634,11 @@ 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;
> + return 0;
> }
>
> static void domain_destroy_mon_state(struct rdt_domain *d)
> @@ -3752,13 +3760,9 @@ 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;
> -
> ret = sysfs_create_mount_point(fs_kobj, "resctrl");
> if (ret)
> - goto cleanup_root;
> + return ret;
>
It is not clear to me why this change is required, could you
please elaborate? It seems that all that is needed is for
rdtgroup_add_files() to move to rdt_get_tree() (which you have done)
and then an additional call to kernfs_remove() in rmdir_all_sub().
I must be missing something, could you please help me understand?
> ret = register_filesystem(&rdt_fs_type);
> if (ret)
> @@ -3791,8 +3795,6 @@ int __init rdtgroup_init(void)
>
> cleanup_mountpoint:
> sysfs_remove_mount_point(fs_kobj, "resctrl");
> -cleanup_root:
> - kernfs_destroy_root(rdt_root);
>
> return ret;
> }
> @@ -3802,5 +3804,4 @@ 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);
> }
>
>
Reinette
