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Date: Sat, 8 Jan 2022 17:38:33 +0300
From: Arseny Maslennikov <ar@...msu.ru>
To: Walt Drummond <walt@...mmond.us>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>,
Arnd Bergmann <arnd@...db.de>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-arch@...r.kernel.org
Subject: Re: [RFC PATCH 8/8] signals: Support BSD VSTATUS, KERNINFO and
SIGINFO
On Mon, Jan 03, 2022 at 10:19:56AM -0800, Walt Drummond wrote:
> Support TTY VSTATUS character, NOKERNINFO local control bit and the
> signal SIGINFO, all as in 4.3BSD.
>
> Signed-off-by: Walt Drummond <walt@...mmond.us>
> ---
> arch/x86/include/asm/signal.h | 2 +-
> arch/x86/include/uapi/asm/signal.h | 4 +-
> drivers/tty/Makefile | 2 +-
> drivers/tty/n_tty.c | 21 +++++
> drivers/tty/tty_io.c | 10 ++-
> drivers/tty/tty_ioctl.c | 4 +
> drivers/tty/tty_status.c | 135 ++++++++++++++++++++++++++++
> fs/proc/array.c | 29 +-----
> include/asm-generic/termios.h | 4 +-
> include/linux/sched.h | 52 ++++++++++-
> include/linux/signal.h | 4 +
> include/linux/tty.h | 8 ++
> include/uapi/asm-generic/ioctls.h | 2 +
> include/uapi/asm-generic/signal.h | 6 +-
> include/uapi/asm-generic/termbits.h | 34 +++----
> 15 files changed, 264 insertions(+), 53 deletions(-)
> create mode 100644 drivers/tty/tty_status.c
>
> <...>
>
> diff --git a/drivers/tty/tty_status.c b/drivers/tty/tty_status.c
> new file mode 100644
> index 000000000000..a9600f5bd48c
> --- /dev/null
> +++ b/drivers/tty/tty_status.c
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: GPL-1.0+
> +/*
> + * tty_status.c --- implements VSTATUS and TIOCSTAT from BSD4.3/4.4
> + *
> + */
> +
> +#include <linux/sched.h>
> +#include <linux/mm.h>
> +#include <linux/tty.h>
> +#include <linux/sched/cputime.h>
> +#include <linux/sched/loadavg.h>
> +#include <linux/pid.h>
> +#include <linux/slab.h>
> +#include <linux/math64.h>
> +
> +#define MSGLEN (160 + TASK_COMM_LEN)
> +
> +inline unsigned long getRSSk(struct mm_struct *mm)
> +{
> + if (mm == NULL)
> + return 0;
> + return get_mm_rss(mm) * PAGE_SIZE / 1024;
> +}
> +
> +inline long nstoms(long l)
> +{
> + l /= NSEC_PER_MSEC * 10;
> + if (l < 10)
> + l *= 10;
> + return l;
> +}
> +
> +inline struct task_struct *compare(struct task_struct *new,
> + struct task_struct *old)
> +{
> + unsigned int ostate, nstate;
> +
> + if (old == NULL)
> + return new;
> +
> + ostate = task_state_index(old);
> + nstate = task_state_index(new);
> +
> + if (ostate == nstate) {
> + if (old->start_time > new->start_time)
> + return old;
> + return new;
> + }
> +
> + if (ostate < nstate)
> + return old;
> +
> + return new;
> +}
> +
> +struct task_struct *pick_process(struct pid *pgrp)
> +{
> + struct task_struct *p, *winner = NULL;
> +
> + read_lock(&tasklist_lock);
> + do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
> + winner = compare(p, winner);
> + } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
> + read_unlock(&tasklist_lock);
> +
> + return winner;
> +}
> +
> +int tty_status(struct tty_struct *tty)
> +{
> + char tname[TASK_COMM_LEN];
> + unsigned long loadavg[3];
> + uint64_t pcpu, cputime, wallclock;
> + struct task_struct *p;
> + struct rusage rusage;
> + struct timespec64 utime, stime, rtime;
> + char msg[MSGLEN] = {0};
> + int len = 0;
> +
> + if (tty == NULL)
> + return -ENOTTY;
> +
> + get_avenrun(loadavg, FIXED_1/200, 0);
> + len += scnprintf((char *)&msg[len], MSGLEN - len, "load: %lu.%02lu ",
> + LOAD_INT(loadavg[0]), LOAD_FRAC(loadavg[0]));
> +
> + if (tty->ctrl.session == NULL) {
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + "not a controlling terminal");
> + goto print;
> + }
> +
> + if (tty->ctrl.pgrp == NULL) {
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + "no foreground process group");
> + goto print;
> + }
> +
> + p = pick_process(tty->ctrl.pgrp);
> + if (p == NULL) {
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + "empty foreground process group");
> + goto print;
> + }
> +
> + get_task_comm(tname, p);
> + getrusage(p, RUSAGE_BOTH, &rusage);
> + wallclock = ktime_get_ns() - p->start_time;
> +
> + utime.tv_sec = rusage.ru_utime.tv_sec;
> + utime.tv_nsec = rusage.ru_utime.tv_usec * NSEC_PER_USEC;
> + stime.tv_sec = rusage.ru_stime.tv_sec;
> + stime.tv_nsec = rusage.ru_stime.tv_usec * NSEC_PER_USEC;
> + rtime = ns_to_timespec64(wallclock);
> +
> + cputime = timespec64_to_ns(&utime) + timespec64_to_ns(&stime);
> + pcpu = div64_u64(cputime * 100, wallclock);
> +
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + /* task, PID, task state */
> + "cmd: %s %d [%s] "
> + /* rtime, utime, stime, %cpu, rss */
> + "%llu.%02lur %llu.%02luu %llu.%02lus %llu%% %luk",
> + tname, task_pid_vnr(p), (char *)get_task_state_name(p),
task_pid_vnr(p) returns the PID of p in the PID namespace of current:
pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
struct pid_namespace *ns)
{
pid_t nr = 0;
rcu_read_lock();
if (!ns)
ns = task_active_pid_ns(current);
nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
rcu_read_unlock();
return nr;
}
struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
{
return ns_of_pid(task_pid(tsk));
}
static inline pid_t task_pid_vnr(struct task_struct *tsk)
{
return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
}
At this point current is an arbitrary kernel worker thread, not p. Most
likely we need another helper function in <linux/sched.h>.
> + rtime.tv_sec, nstoms(rtime.tv_nsec),
> + utime.tv_sec, nstoms(utime.tv_nsec),
> + stime.tv_sec, nstoms(stime.tv_nsec),
> + pcpu, getRSSk(p->mm));
> +
> +print:
> + len += scnprintf((char *)&msg[len], MSGLEN - len, "\r\n");
> + tty_write_message(tty, msg);
> +
> + return 0;
> +}
>
> <...>
>
> --
> 2.30.2
>
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