Re: [patch cr 3/4] c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat

Andrew Morton
2012-02-02T23:26:57Z

On Mon, 30 Jan 2012 18:09:08 +0400
Cyrill Gorcunov <gorcunov@openvz.org> wrote:

> We would like to have an ability to restore command line
> arguments and envirion pointers so the task being restored
> would print appropriate values in /proc/pid/cmdline and
> /proc/pid/envirion. The exit_code is needed to restore
> zombie tasks.
>
> ...
>
> --- linux-2.6.git.orig/fs/proc/array.c
> +++ linux-2.6.git/fs/proc/array.c
> @@ -464,7 +464,7 @@ static int do_task_stat(struct seq_file
>
> seq_printf(m, "%d (%s) %c %d %d %d %d %d %u %lu \
> %lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
> -%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld %lu %lu %lu\n",
> +%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld ",
> pid_nr_ns(pid, ns),
> tcomm,
> state,
> @@ -511,10 +511,25 @@ static int do_task_stat(struct seq_file
> task->policy,
> (unsigned long long)delayacct_blkio_ticks(task),
> cputime_to_clock_t(gtime),
> - cputime_to_clock_t(cgtime),
> - (mm && permitted) ? mm->start_data : 0,
> - (mm && permitted) ? mm->end_data : 0,
> - (mm && permitted) ? mm->start_brk : 0);
> + cputime_to_clock_t(cgtime));
> +
> + if (mm && permitted) {
> + seq_printf(m, "%lu %lu %lu %lu %lu %lu %lu ",
> + mm->start_data,
> + mm->end_data,
> + mm->start_brk,
> + mm->arg_start,
> + mm->arg_end,
> + mm->env_start,
> + mm->env_end);
> + } else
> + seq_printf(m, "0 0 0 0 0 0 0 ");

heh.

We have a whizzy new num_to_str() in -mm which can later be used to
speed this up.

This actually means that your patch will conflict horridly with
procfs-add-num_to_str-to-speed-up-proc-stat.patch, because that patch
redoes /proc/stat handling. I guess I can take care of that issue.

> +
> + if (permitted)
> + seq_printf(m, "%d\n", task->exit_code);
> + else
> + seq_printf(m, "0\n");
> +
> if (mm)
> mmput(mm);
> return 0;