linux-kernel - Re: [PATCH 10/24] x86/resctrl: Move the schema names into struct resctrl

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Message-ID: <20201110113922.GA94467@poplar>
Date:   Tue, 10 Nov 2020 11:39:22 +0000
From:   Jamie Iles <jamie@...iainc.com>
To:     James Morse <james.morse@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        shameerali.kolothum.thodi@...wei.com,
        Jamie Iles <jamie@...iainc.com>,
        D Scott Phillips OS <scott@...amperecomputing.com>
Subject: Re: [PATCH 10/24] x86/resctrl: Move the schema names into struct
 resctrl_schema

Hi James,

On Fri, Oct 30, 2020 at 04:11:06PM +0000, James Morse wrote:
> Move the names used for the schemata file out of the resource and
> into struct resctrl_schema. This allows one resource to have two
> different names, based on the other schema properties.
> 
> This patch copies the names, eventually resctrl will generate them.
> 
> Remove the arch code's max_name_width, this is now resctrl's
> problem.
> 
> Signed-off-by: James Morse <james.morse@....com>
> ---
>  arch/x86/kernel/cpu/resctrl/core.c        |  9 ++-------
>  arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 10 +++-------
>  arch/x86/kernel/cpu/resctrl/internal.h    |  2 +-
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 17 ++++++++++++-----
>  include/linux/resctrl.h                   |  7 +++++++
>  5 files changed, 25 insertions(+), 20 deletions(-)
...
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 27671a654f8b..5294ae0c3ed9 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -248,7 +248,7 @@ struct rdtgroup {
>  /* List of all resource groups */
>  extern struct list_head rdt_all_groups;
>  
> -extern int max_name_width, max_data_width;
> +extern int max_data_width;
>  
>  int __init rdtgroup_init(void);
>  void __exit rdtgroup_exit(void);
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 311a3890bc53..48f4d6783647 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1440,8 +1440,8 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
>  			rdt_last_cmd_puts("Cache domain offline\n");
>  			ret = -ENODEV;
>  		} else {
> -			seq_printf(s, "%*s:", max_name_width,
> -				   rdtgrp->plr->s->res->name);
> +			seq_printf(s, "%*s:", RESCTRL_NAME_LEN,
> +				   rdtgrp->plr->s->name);
>  			size = rdtgroup_cbm_to_size(rdtgrp->plr->s->res,
>  						    rdtgrp->plr->d,
>  						    rdtgrp->plr->cbm);
> @@ -1454,7 +1454,7 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
>  		r = schema->res;
>  
>  		sep = false;
> -		seq_printf(s, "%*s:", max_name_width, r->name);
> +		seq_printf(s, "%*s:", RESCTRL_NAME_LEN, schema->name);
>  		list_for_each_entry(d, &r->domains, list) {
>  			hw_dom = resctrl_to_arch_dom(d);
>  			if (sep)
> @@ -1827,7 +1827,7 @@ static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
>  	list_for_each_entry(s, &resctrl_all_schema, list) {
>  		r = s->res;
>  		fflags =  r->fflags | RF_CTRL_INFO;
> -		ret = rdtgroup_mkdir_info_resdir(s, r->name, fflags);
> +		ret = rdtgroup_mkdir_info_resdir(s, s->name, fflags);
>  		if (ret)
>  			goto out_destroy;
>  	}
> @@ -2140,6 +2140,7 @@ static int create_schemata_list(void)
>  {
>  	struct resctrl_schema *s;
>  	struct rdt_resource *r;
> +	int ret;
>  
>  	for_each_alloc_enabled_rdt_resource(r) {
>  		s = kzalloc(sizeof(*s), GFP_KERNEL);
> @@ -2150,6 +2151,12 @@ static int create_schemata_list(void)
>  		s->num_closid = resctrl_arch_get_num_closid(r);
>  		s->conf_type = resctrl_to_arch_res(r)->conf_type;
>  
> +		ret = snprintf(s->name, sizeof(s->name), r->name);
> +		if (ret >= sizeof(s->name)) {
> +			kfree(s);
> +			return -EINVAL;
> +		}
> +

How about:

+		ret = strscpy(s->name, r->name, sizeof(s->name));
+		if (ret < 0)) {
+			kfree(s);
+			return -EINVAL;
+		}

So that there isn't a non-constant format specifier that'll trip 
Coverity+friends up later?

Thanks,

Jamie