linux-kernel - Re: [patch v12 06/13] procfs: add per-pid task isolation state

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Date:   Tue, 26 Apr 2022 01:27:32 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Marcelo Tosatti <mtosatti@...hat.com>, linux-kernel@...r.kernel.org
Cc:     Nitesh Lal <nilal@...hat.com>,
        Nicolas Saenz Julienne <nsaenzju@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Alex Belits <abelits@...its.com>, Peter Xu <peterx@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Oscar Shiang <oscar0225@...email.tw>
Subject: Re: [patch v12 06/13] procfs: add per-pid task isolation state

On Tue, Mar 15 2022 at 12:31, Marcelo Tosatti wrote:
> Add /proc/pid/task_isolation file, to query the state of
> task isolation configuration.
>
> ---

Lacks a Signed-off-by...

>  fs/proc/base.c |   68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++

> +#ifdef CONFIG_TASK_ISOLATION
> +
> +struct qoptions {
> +	unsigned long mask;
> +	char *name;
> +};
> +
> +static struct qoptions iopts[] = {
> +	{ISOL_F_QUIESCE, "quiesce"},
> +};
> +#define ILEN (sizeof(iopts) / sizeof(struct qoptions))

Reinventing ARRAY_SIZE() just because this isolation muck is special?

> +static struct qoptions qopts[] = {
> +	{ISOL_F_QUIESCE_VMSTATS, "vmstat_sync"},
> +};
> +#define QLEN (sizeof(qopts) / sizeof(struct qoptions))

Ditto.

> +static void show_isolation_state(struct seq_file *m,
> +				 struct qoptions *iopt,
> +				 int mask,
> +				 const char *hdr)
> +{
> +	int i;
> +
> +	seq_printf(m, hdr);
> +	for (i = 0; i < ILEN; i++) {
> +		if (mask & iopt->mask)
> +			seq_printf(m, "%s ", iopt->name);
> +		iopt++;
> +	}
> +	if (mask == 0)
> +		seq_printf(m, "none ");
> +	seq_printf(m, "\n");
> +}
> +
> +int proc_pid_task_isolation(struct seq_file *m, struct pid_namespace *ns,
> +			    struct pid *pid, struct task_struct *t)

This is required to be global without a prototype because?

> +{
> +	int active_mask, quiesce_mask, conf_mask;
> +	struct task_isol_info *task_isol_info;
> +	struct inode *inode = m->private;
> +	struct task_struct *task = get_proc_task(inode);
> +
> +	task_isol_info = t->task_isol_info;
> +	if (!task_isol_info)
> +		active_mask = quiesce_mask = conf_mask = 0;
> +	else {
> +		active_mask = task_isol_info->active_mask;
> +		quiesce_mask = task_isol_info->quiesce_mask;
> +		conf_mask = task_isol_info->conf_mask;
> +	}
> +
> +	show_isolation_state(m, iopts, conf_mask, "Configured state: ");
> +	show_isolation_state(m, iopts, active_mask, "Active state: ");
> +	show_isolation_state(m, qopts, quiesce_mask, "Quiescing: ");

And once you have 10 features with 10 subfeature masks supported, all of
this ends up in fs/proc/base.c just because all of this nonsense is
required to be disconnected from the actual task isolation code, right?

Just because a lot of crap has been dumped over time into that file does
not justify to mindlessly dump more crap into it.

Thanks,

        tglx