Hi Babu,
Please do note that the subject is no longer accurate.
On 8/11/2023 1:10 PM, Babu Moger wrote:
> The resctrl default control group is created during kernel init time.
> If the new files are to be added to the default group based on the mount
> option, then each file needs to be created separately and call
> kernfs_activate() again.
>
> This can be avoided if all the files are created during the mount and
> destroyed during the umount. So, move the default group creation
> in rdt_get_tree() and removal in rdt_kill_sb().
How about a slight rewording (please feel free to change):
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>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 50 +++++++++++++++++---------------
> 2 files changed, 27 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 37800724e002..2bd92c0c3b0c 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -602,5 +602,6 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
> void __init thread_throttle_mode_init(void);
> void __init mbm_config_rftype_init(const char *config);
> void rdt_staged_configs_clear(void);
> +int rdtgroup_setup_root(struct rdt_fs_context *ctx);
>
> #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 0805fac04401..a7453c93bad4 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2521,10 +2521,14 @@ 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();
> @@ -2533,6 +2537,12 @@ 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;
> @@ -2589,6 +2599,8 @@ static int rdt_get_tree(struct fs_context *fc)
> schemata_list_destroy();
> out_ctx:
> rdt_disable_ctx(ctx);
> +out_root:
> + kernfs_destroy_root(rdt_root);
Please ensure that all rdtgroup_setup_root() cleanup is done
here. It seems to me that rdtgroup_default.kn can be left pointing
to freed memory. Since this cleanup is done multiple places (here
and rdt_kill_sb()) it may help to create a helper.
Apart from this the patch looks good to me.
Thank you.
Reinette
