Re: [PATCH v8 6/8] x86/resctrl: Move default group file creation to mount

[Moger, Babu]

Hi Fenghua,

On 9/1/2023 6:21 PM, Fenghua Yu wrote:
> Hi, Babu,
>
> On 8/21/23 16:30, 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>
> > Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> > ---
> >   arch/x86/kernel/cpu/resctrl/internal.h |  2 +
> >   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 55 +++++++++++++++-----------
> >   2 files changed, 33 insertions(+), 24 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/resctrl/internal.h 
> > b/arch/x86/kernel/cpu/resctrl/internal.h
> > index b09e7abd1299..44ad98f8c7af 100644
> > --- a/arch/x86/kernel/cpu/resctrl/internal.h
> > +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> > @@ -611,5 +611,7 @@ 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);
> > +void rdtgroup_destroy_root(void);
>
> These two functions are called only in rdtgroup.c. Why are they 
> exposed here?
Yes. Removed it now.
> >     #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 80a4f76bc34b..98f9f880c30b 100644
> > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > @@ -2516,10 +2516,14 @@ 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();
> > @@ -2528,6 +2532,12 @@ 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;
> > @@ -2584,6 +2594,8 @@ 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);
> > @@ -2654,7 +2666,6 @@ 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;
> > @@ -2824,6 +2835,7 @@ 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);
> > @@ -3705,10 +3717,8 @@ static struct kernfs_syscall_ops 
> > rdtgroup_kf_syscall_ops = {
> >       .show_options    = rdtgroup_show_options,
> >   };
> >   -static int __init rdtgroup_setup_root(void)
> > +int rdtgroup_setup_root(struct rdt_fs_context *ctx)
>
> Since rdtgroup_setup_root() is called only in this file, need to add 
> "static".

Yes. Taken care of it now.


> >   {
> > -    int ret;
> > -
> >       rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
> >                         KERNFS_ROOT_CREATE_DEACTIVATED |
> >                         KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
> > @@ -3716,6 +3726,20 @@ 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;
> > +}
> > +
> > +void rdtgroup_destroy_root(void)
>
> Ditto.

Thanks

Babu