linux-kernel - Re: [PATCH 1/2] /proc/stat: Extract irqs counting code into show_stat

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Date:   Mon, 7 Jan 2019 13:42:07 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        Miklos Szeredi <miklos@...redi.hu>,
        Daniel Colascione <dancol@...gle.com>,
        Dave Chinner <david@...morbit.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH 1/2] /proc/stat: Extract irqs counting code into show_stat_irqs()

On Mon, Jan 7, 2019 at 7:13 AM Waiman Long <longman@...hat.com> wrote:
>
> The code that generates the "intr" line of /proc/stat is now moved
> from show_stat() into a new function - show_stat_irqs(). There is no
> functional change.
>
> Signed-off-by: Waiman Long <longman@...hat.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  fs/proc/stat.c | 39 +++++++++++++++++++++++++++++----------
>  1 file changed, 29 insertions(+), 10 deletions(-)
>
> diff --git a/fs/proc/stat.c b/fs/proc/stat.c
> index 535eda7..4b06f1b 100644
> --- a/fs/proc/stat.c
> +++ b/fs/proc/stat.c
> @@ -79,12 +79,38 @@ static u64 get_iowait_time(int cpu)
>
>  #endif
>
> +static u64 compute_stat_irqs_sum(void)
> +{
> +       int i;
> +       u64 sum = 0;
> +
> +       for_each_possible_cpu(i) {
> +               sum += kstat_cpu_irqs_sum(i);
> +               sum += arch_irq_stat_cpu(i);
> +       }
> +       sum += arch_irq_stat();
> +       return sum;
> +}
> +
> +/*
> + * Print out the "intr" line of /proc/stat.
> + */
> +static void show_stat_irqs(struct seq_file *p)
> +{
> +       int i;
> +
> +       seq_put_decimal_ull(p, "intr ", compute_stat_irqs_sum());
> +       for_each_irq_nr(i)
> +               seq_put_decimal_ull(p, " ", kstat_irqs_usr(i));
> +
> +       seq_putc(p, '\n');
> +}
> +
>  static int show_stat(struct seq_file *p, void *v)
>  {
>         int i, j;
>         u64 user, nice, system, idle, iowait, irq, softirq, steal;
>         u64 guest, guest_nice;
> -       u64 sum = 0;
>         u64 sum_softirq = 0;
>         unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
>         struct timespec64 boottime;
> @@ -105,8 +131,6 @@ static int show_stat(struct seq_file *p, void *v)
>                 steal += kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
>                 guest += kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
>                 guest_nice += kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
> -               sum += kstat_cpu_irqs_sum(i);
> -               sum += arch_irq_stat_cpu(i);
>
>                 for (j = 0; j < NR_SOFTIRQS; j++) {
>                         unsigned int softirq_stat = kstat_softirqs_cpu(j, i);
> @@ -115,7 +139,6 @@ static int show_stat(struct seq_file *p, void *v)
>                         sum_softirq += softirq_stat;
>                 }
>         }
> -       sum += arch_irq_stat();
>
>         seq_put_decimal_ull(p, "cpu  ", nsec_to_clock_t(user));
>         seq_put_decimal_ull(p, " ", nsec_to_clock_t(nice));
> @@ -154,14 +177,10 @@ static int show_stat(struct seq_file *p, void *v)
>                 seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
>                 seq_putc(p, '\n');
>         }
> -       seq_put_decimal_ull(p, "intr ", (unsigned long long)sum);
> -
> -       /* sum again ? it could be updated? */
> -       for_each_irq_nr(j)
> -               seq_put_decimal_ull(p, " ", kstat_irqs_usr(j));
> +       show_stat_irqs(p);
>
>         seq_printf(p,
> -               "\nctxt %llu\n"
> +               "ctxt %llu\n"
>                 "btime %llu\n"
>                 "processes %lu\n"
>                 "procs_running %lu\n"
> --
> 1.8.3.1
>


-- 
Kees Cook