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

["Moger, Babu" <bmoger@amd.com>]

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@intel.com>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
>>   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