linux-kernel - Re: [PATCH] x86/resctrl: Use seq

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Message-ID: <cb908d7f-db6a-4b04-8867-bf36fb2dd45f@intel.com>
Date: Tue, 16 Jul 2024 14:43:57 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Markus Elfring <Markus.Elfring@....de>, <x86@...nel.org>,
	<kernel-janitors@...r.kernel.org>, Borislav Petkov <bp@...en8.de>, "Dave
 Hansen" <dave.hansen@...ux.intel.com>, Fenghua Yu <fenghua.yu@...el.com>, "H.
 Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>, Thomas Gleixner
	<tglx@...utronix.de>
CC: LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/resctrl: Use seq_putc() in two functions

Hi Markus,

On 7/13/24 2:00 AM, Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Sat, 13 Jul 2024 10:43:14 +0200
> 
> Single characters should be put into a sequence.
> Thus use the corresponding function “seq_putc”.
> 
> This issue was transformed by using the Coccinelle software.

Could you please point me to how you accomplished this? I tried
on the latest upstream as well as the latest resctrl staged
changes in tip's x86/cache but the needed coccinelle scripts do
not seem to be available. I tried by running the commands below. It appeared
to run many coccinelle scripts but there was not one related to this change.
Is this a new coccinelle script outside of the kernel or still
on its way upstream?

make C=2 CHECK=scripts/coccicheck MODE=report arch/x86/kernel/cpu/resctrl/rdtgroup.o
make C=2 CHECK=scripts/coccicheck MODE=report arch/x86/kernel/cpu/resctrl/ctrlmondata.o

> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>   arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 4 ++--
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 4 ++--
>   2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 50fa1fe9a073..dce68f19c29d 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -452,7 +452,7 @@ static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int clo
>   	seq_printf(s, "%*s:", max_name_width, schema->name);
>   	list_for_each_entry(dom, &r->ctrl_domains, hdr.list) {
>   		if (sep)
> -			seq_puts(s, ";");
> +			seq_putc(s, ';');
> 
>   		if (is_mba_sc(r))
>   			ctrl_val = dom->mbps_val[closid];
> @@ -464,7 +464,7 @@ static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int clo
>   			   ctrl_val);
>   		sep = true;
>   	}
> -	seq_puts(s, "\n");
> +	seq_putc(s, '\n');
>   }
> 
>   int rdtgroup_schemata_show(struct kernfs_open_file *of,
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index d7163b764c62..d4e216073e7a 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1605,7 +1605,7 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid
> 
>   	list_for_each_entry(dom, &r->mon_domains, hdr.list) {
>   		if (sep)
> -			seq_puts(s, ";");
> +			seq_putc(s, ';');
> 
>   		memset(&mon_info, 0, sizeof(struct mon_config_info));
>   		mon_info.evtid = evtid;
> @@ -1614,7 +1614,7 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid
>   		seq_printf(s, "%d=0x%02x", dom->hdr.id, mon_info.mon_config);
>   		sep = true;
>   	}
> -	seq_puts(s, "\n");
> +	seq_putc(s, '\n');
> 
>   	mutex_unlock(&rdtgroup_mutex);
>   	cpus_read_unlock();
> --
> 2.45.2
> 


Could you please highlight the benefit of this change? Looking at seq_puts() implementation, thanks
to [1], it seems to me these seq_puts() calls will result in seq_putc() anyway?

Reinette

[1] https://lore.kernel.org/all/a8589bffe4830dafcb9111e22acf06603fea7132.1713781332.git.christophe.jaillet@wanadoo.fr/