Messages in this thread Patch in this message | | | From | Walt Drummond <> | Subject | [PATCH 3/3] status: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called. | Date | Mon, 17 Jan 2022 20:43:23 -0800 |
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When triggered by pressing the VSTATUS key or calling the TIOCSTAT ioctl, the n_tty line discipline will display a message on the user's tty that provides basic information about the system and an 'interesting' process in the current foreground process group, eg:
load: 0.58 cmd: sleep 744474 [sleeping] 0.36r 0.00u 0.00s 0% 772k
The status message provides: - System load average - Command name and process id (from the perspective of the session) - Scheduler state - Total wall-clock run time - User space run time - System space run time - Percentage of on-cpu time - Resident set size
The message is only displayed when the tty has the VSTATUS character set and the local flag NOKERNINFO disabled; it is always displayed when TIOCSTAT is called regardless of tty settings.
Signed-off-by: Walt Drummond <walt@drummond.us> --- drivers/tty/Makefile | 2 +- drivers/tty/n_tty.c | 37 +++++++++ drivers/tty/n_tty_status.c | 162 +++++++++++++++++++++++++++++++++++++ drivers/tty/tty_io.c | 2 +- include/linux/tty.h | 123 ++++++++++++++-------------- 5 files changed, 265 insertions(+), 61 deletions(-) create mode 100644 drivers/tty/n_tty_status.c
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile index 07aca5184a55..84bc99aebcff 100644 --- a/drivers/tty/Makefile +++ b/drivers/tty/Makefile @@ -2,7 +2,7 @@ obj-$(CONFIG_TTY) += tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \ tty_buffer.o tty_port.o tty_mutex.o \ tty_ldsem.o tty_baudrate.o tty_jobctrl.o \ - n_null.o + n_null.o n_tty_status.o obj-$(CONFIG_LEGACY_PTYS) += pty.o obj-$(CONFIG_UNIX98_PTYS) += pty.o obj-$(CONFIG_AUDIT) += tty_audit.o diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 6a6e7da80095..2e9b038e84e0 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -80,6 +80,7 @@ #define ECHO_BLOCK 256 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32) +#define STATUS_LINE_LEN 160 /* tty status line will truncate at this length */ #undef N_TTY_TRACE #ifdef N_TTY_TRACE @@ -127,6 +128,8 @@ struct n_tty_data { struct mutex output_lock; }; +static int n_tty_status(struct tty_struct *tty); + #define MASK(x) ((x) & (N_TTY_BUF_SIZE - 1)) static inline size_t read_cnt(struct n_tty_data *ldata) @@ -1334,6 +1337,11 @@ static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) commit_echoes(tty); return; } + if (c == STATUS_CHAR(tty)) { + if (!L_NOKERNINFO(tty)) + n_tty_status(tty); + return; + } if (c == '\n') { if (L_ECHO(tty) || L_ECHONL(tty)) { echo_char_raw('\n', ldata); @@ -1763,6 +1771,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) set_bit(EOF_CHAR(tty), ldata->char_map); set_bit('\n', ldata->char_map); set_bit(EOL_CHAR(tty), ldata->char_map); + set_bit(STATUS_CHAR(tty), ldata->char_map); if (L_IEXTEN(tty)) { set_bit(WERASE_CHAR(tty), ldata->char_map); set_bit(LNEXT_CHAR(tty), ldata->char_map); @@ -2412,6 +2421,29 @@ static unsigned long inq_canon(struct n_tty_data *ldata) return nr; } +static int n_tty_status(struct tty_struct *tty) +{ + struct n_tty_data *ldata = tty->disc_data; + char *buf, msg[STATUS_LINE_LEN] = {0}; + int ret = 0; + size_t len = STATUS_LINE_LEN - 1; + + buf = (char *) &msg; + ret = n_tty_get_status(tty, buf + 1, &len); + if (ret) + return ret; + + if (ldata->column != 0) { + msg[0] = '\n'; + len++; + } else { + buf++; + } + + do_n_tty_write(tty, NULL, buf, len); + return 0; +} + static int n_tty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg) { @@ -2429,6 +2461,11 @@ static int n_tty_ioctl(struct tty_struct *tty, struct file *file, retval = read_cnt(ldata); up_write(&tty->termios_rwsem); return put_user(retval, (unsigned int __user *) arg); + case TIOCSTAT: + down_read(&tty->termios_rwsem); + retval = n_tty_status(tty); + up_read(&tty->termios_rwsem); + return retval; default: return n_tty_ioctl_helper(tty, cmd, arg); } diff --git a/drivers/tty/n_tty_status.c b/drivers/tty/n_tty_status.c new file mode 100644 index 000000000000..269776db0640 --- /dev/null +++ b/drivers/tty/n_tty_status.c @@ -0,0 +1,162 @@ +// SPDX-License-Identifier: GPL-1.0+ +/* + * n_tty_status.c --- implements VSTATUS and TIOCSTAT from BSD + * + * Display a basic status message containing information about the + * foreground process and system load on the users tty, triggered by + * the VSTATUS character or TIOCSTAT. Ex, + * + * load: 14.11 cmd: tcsh 19623 [running] 185756.62r 88.00u 17.50s 0% 4260k + * + */ + +#include <linux/tty.h> +#include <linux/mm.h> +#include <linux/sched/loadavg.h> + +static const char * const task_state_unknown = "unknown"; +static const char * const task_state_array[] = { + "running", + "sleeping", + "disk sleep", + "stopped", + "tracing stop", + "dead", + "zombie", + "parked", + "idle", +}; + +static inline unsigned long getRSSk(struct mm_struct *mm) +{ + if (mm == NULL) + return 0; + return get_mm_rss(mm) * PAGE_SIZE / 1024; +} + +static inline long frac_sec(long l) +{ + l /= NSEC_PER_MSEC * 10; + if (l < 10) + l *= 10; + return l; +} + +static 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; +} + +static struct task_struct *pick_process(struct pid *pgrp) +{ + struct task_struct *new, *winner = NULL; + + read_lock(&tasklist_lock); + do_each_pid_task(pgrp, PIDTYPE_PGID, new) { + winner = compare(new, winner); + } while_each_pid_task(pgrp, PIDTYPE_PGID, new); + read_unlock(&tasklist_lock); + + return winner; +} + +/* We want the pid from the context of session */ +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty) +{ + return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns_of_pid(tty->ctrl.session)); +} + +static inline const char *get_task_state_name(struct task_struct *tsk) +{ + + int index; + + index = task_state_index(tsk); + if (index > ARRAY_SIZE(task_state_array)) + return task_state_unknown; + return task_state_array[index]; +} + +int n_tty_get_status(struct tty_struct *tty, char *msg, size_t *msglen) +{ + unsigned long loadavg[3]; + uint64_t pcpu, cputime, wallclock; + struct task_struct *p; + struct rusage rusage; + struct timespec64 utime, stime, rtime; + char tname[TASK_COMM_LEN]; + size_t len; + + if (tty == NULL) + return -ENOTTY; + + get_avenrun(loadavg, FIXED_1/200, 0); + len = scnprintf(msg + len, *msglen - len, "load: %lu.%02lu ", + LOAD_INT(loadavg[0]), LOAD_FRAC(loadavg[0])); + + if (tty->ctrl.session == NULL) { + len += scnprintf(msg + len, *msglen - len, + "not a controlling terminal\n"); + goto out; + } + + if (tty->ctrl.pgrp == NULL) { + len += scnprintf(msg + len, *msglen - len, + "no foreground process group\n"); + goto out; + } + + p = pick_process(tty->ctrl.pgrp); + if (p == NULL) { + len += scnprintf(msg + len, *msglen - len, + "empty foreground process group\n"); + goto out; + } + + 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(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\n", + tname, __get_pid(p, tty), + (char *)get_task_state_name(p), + rtime.tv_sec, frac_sec(rtime.tv_nsec), + utime.tv_sec, frac_sec(utime.tv_nsec), + stime.tv_sec, frac_sec(stime.tv_nsec), + pcpu, getRSSk(p->mm)); + +out: + *msglen = len; + return 0; +} diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 6616d4a0d41d..f2f4f48ea502 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -125,7 +125,7 @@ struct ktermios tty_std_termios = { /* for the benefit of tty drivers */ .c_oflag = OPOST | ONLCR, .c_cflag = B38400 | CS8 | CREAD | HUPCL, .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | - ECHOCTL | ECHOKE | IEXTEN, + ECHOCTL | ECHOKE | IEXTEN | NOKERNINFO, .c_cc = INIT_C_CC, .c_ispeed = 38400, .c_ospeed = 38400, diff --git a/include/linux/tty.h b/include/linux/tty.h index 5dbd7c5afac7..e6ba6ce2efcb 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -49,71 +49,73 @@ #define WERASE_CHAR(tty) ((tty)->termios.c_cc[VWERASE]) #define LNEXT_CHAR(tty) ((tty)->termios.c_cc[VLNEXT]) #define EOL2_CHAR(tty) ((tty)->termios.c_cc[VEOL2]) +#define STATUS_CHAR(tty) ((tty)->termios.c_cc[VSTATUS]) #define _I_FLAG(tty, f) ((tty)->termios.c_iflag & (f)) #define _O_FLAG(tty, f) ((tty)->termios.c_oflag & (f)) #define _C_FLAG(tty, f) ((tty)->termios.c_cflag & (f)) #define _L_FLAG(tty, f) ((tty)->termios.c_lflag & (f)) -#define I_IGNBRK(tty) _I_FLAG((tty), IGNBRK) -#define I_BRKINT(tty) _I_FLAG((tty), BRKINT) -#define I_IGNPAR(tty) _I_FLAG((tty), IGNPAR) -#define I_PARMRK(tty) _I_FLAG((tty), PARMRK) -#define I_INPCK(tty) _I_FLAG((tty), INPCK) -#define I_ISTRIP(tty) _I_FLAG((tty), ISTRIP) -#define I_INLCR(tty) _I_FLAG((tty), INLCR) -#define I_IGNCR(tty) _I_FLAG((tty), IGNCR) -#define I_ICRNL(tty) _I_FLAG((tty), ICRNL) -#define I_IUCLC(tty) _I_FLAG((tty), IUCLC) -#define I_IXON(tty) _I_FLAG((tty), IXON) -#define I_IXANY(tty) _I_FLAG((tty), IXANY) -#define I_IXOFF(tty) _I_FLAG((tty), IXOFF) -#define I_IMAXBEL(tty) _I_FLAG((tty), IMAXBEL) -#define I_IUTF8(tty) _I_FLAG((tty), IUTF8) - -#define O_OPOST(tty) _O_FLAG((tty), OPOST) -#define O_OLCUC(tty) _O_FLAG((tty), OLCUC) -#define O_ONLCR(tty) _O_FLAG((tty), ONLCR) -#define O_OCRNL(tty) _O_FLAG((tty), OCRNL) -#define O_ONOCR(tty) _O_FLAG((tty), ONOCR) -#define O_ONLRET(tty) _O_FLAG((tty), ONLRET) -#define O_OFILL(tty) _O_FLAG((tty), OFILL) -#define O_OFDEL(tty) _O_FLAG((tty), OFDEL) -#define O_NLDLY(tty) _O_FLAG((tty), NLDLY) -#define O_CRDLY(tty) _O_FLAG((tty), CRDLY) -#define O_TABDLY(tty) _O_FLAG((tty), TABDLY) -#define O_BSDLY(tty) _O_FLAG((tty), BSDLY) -#define O_VTDLY(tty) _O_FLAG((tty), VTDLY) -#define O_FFDLY(tty) _O_FLAG((tty), FFDLY) - -#define C_BAUD(tty) _C_FLAG((tty), CBAUD) -#define C_CSIZE(tty) _C_FLAG((tty), CSIZE) -#define C_CSTOPB(tty) _C_FLAG((tty), CSTOPB) -#define C_CREAD(tty) _C_FLAG((tty), CREAD) -#define C_PARENB(tty) _C_FLAG((tty), PARENB) -#define C_PARODD(tty) _C_FLAG((tty), PARODD) -#define C_HUPCL(tty) _C_FLAG((tty), HUPCL) -#define C_CLOCAL(tty) _C_FLAG((tty), CLOCAL) -#define C_CIBAUD(tty) _C_FLAG((tty), CIBAUD) -#define C_CRTSCTS(tty) _C_FLAG((tty), CRTSCTS) -#define C_CMSPAR(tty) _C_FLAG((tty), CMSPAR) - -#define L_ISIG(tty) _L_FLAG((tty), ISIG) -#define L_ICANON(tty) _L_FLAG((tty), ICANON) -#define L_XCASE(tty) _L_FLAG((tty), XCASE) -#define L_ECHO(tty) _L_FLAG((tty), ECHO) -#define L_ECHOE(tty) _L_FLAG((tty), ECHOE) -#define L_ECHOK(tty) _L_FLAG((tty), ECHOK) -#define L_ECHONL(tty) _L_FLAG((tty), ECHONL) -#define L_NOFLSH(tty) _L_FLAG((tty), NOFLSH) -#define L_TOSTOP(tty) _L_FLAG((tty), TOSTOP) -#define L_ECHOCTL(tty) _L_FLAG((tty), ECHOCTL) -#define L_ECHOPRT(tty) _L_FLAG((tty), ECHOPRT) -#define L_ECHOKE(tty) _L_FLAG((tty), ECHOKE) -#define L_FLUSHO(tty) _L_FLAG((tty), FLUSHO) -#define L_PENDIN(tty) _L_FLAG((tty), PENDIN) -#define L_IEXTEN(tty) _L_FLAG((tty), IEXTEN) -#define L_EXTPROC(tty) _L_FLAG((tty), EXTPROC) +#define I_IGNBRK(tty) _I_FLAG((tty), IGNBRK) +#define I_BRKINT(tty) _I_FLAG((tty), BRKINT) +#define I_IGNPAR(tty) _I_FLAG((tty), IGNPAR) +#define I_PARMRK(tty) _I_FLAG((tty), PARMRK) +#define I_INPCK(tty) _I_FLAG((tty), INPCK) +#define I_ISTRIP(tty) _I_FLAG((tty), ISTRIP) +#define I_INLCR(tty) _I_FLAG((tty), INLCR) +#define I_IGNCR(tty) _I_FLAG((tty), IGNCR) +#define I_ICRNL(tty) _I_FLAG((tty), ICRNL) +#define I_IUCLC(tty) _I_FLAG((tty), IUCLC) +#define I_IXON(tty) _I_FLAG((tty), IXON) +#define I_IXANY(tty) _I_FLAG((tty), IXANY) +#define I_IXOFF(tty) _I_FLAG((tty), IXOFF) +#define I_IMAXBEL(tty) _I_FLAG((tty), IMAXBEL) +#define I_IUTF8(tty) _I_FLAG((tty), IUTF8) + +#define O_OPOST(tty) _O_FLAG((tty), OPOST) +#define O_OLCUC(tty) _O_FLAG((tty), OLCUC) +#define O_ONLCR(tty) _O_FLAG((tty), ONLCR) +#define O_OCRNL(tty) _O_FLAG((tty), OCRNL) +#define O_ONOCR(tty) _O_FLAG((tty), ONOCR) +#define O_ONLRET(tty) _O_FLAG((tty), ONLRET) +#define O_OFILL(tty) _O_FLAG((tty), OFILL) +#define O_OFDEL(tty) _O_FLAG((tty), OFDEL) +#define O_NLDLY(tty) _O_FLAG((tty), NLDLY) +#define O_CRDLY(tty) _O_FLAG((tty), CRDLY) +#define O_TABDLY(tty) _O_FLAG((tty), TABDLY) +#define O_BSDLY(tty) _O_FLAG((tty), BSDLY) +#define O_VTDLY(tty) _O_FLAG((tty), VTDLY) +#define O_FFDLY(tty) _O_FLAG((tty), FFDLY) + +#define C_BAUD(tty) _C_FLAG((tty), CBAUD) +#define C_CSIZE(tty) _C_FLAG((tty), CSIZE) +#define C_CSTOPB(tty) _C_FLAG((tty), CSTOPB) +#define C_CREAD(tty) _C_FLAG((tty), CREAD) +#define C_PARENB(tty) _C_FLAG((tty), PARENB) +#define C_PARODD(tty) _C_FLAG((tty), PARODD) +#define C_HUPCL(tty) _C_FLAG((tty), HUPCL) +#define C_CLOCAL(tty) _C_FLAG((tty), CLOCAL) +#define C_CIBAUD(tty) _C_FLAG((tty), CIBAUD) +#define C_CRTSCTS(tty) _C_FLAG((tty), CRTSCTS) +#define C_CMSPAR(tty) _C_FLAG((tty), CMSPAR) + +#define L_ISIG(tty) _L_FLAG((tty), ISIG) +#define L_ICANON(tty) _L_FLAG((tty), ICANON) +#define L_XCASE(tty) _L_FLAG((tty), XCASE) +#define L_ECHO(tty) _L_FLAG((tty), ECHO) +#define L_ECHOE(tty) _L_FLAG((tty), ECHOE) +#define L_ECHOK(tty) _L_FLAG((tty), ECHOK) +#define L_ECHONL(tty) _L_FLAG((tty), ECHONL) +#define L_NOFLSH(tty) _L_FLAG((tty), NOFLSH) +#define L_TOSTOP(tty) _L_FLAG((tty), TOSTOP) +#define L_ECHOCTL(tty) _L_FLAG((tty), ECHOCTL) +#define L_ECHOPRT(tty) _L_FLAG((tty), ECHOPRT) +#define L_ECHOKE(tty) _L_FLAG((tty), ECHOKE) +#define L_FLUSHO(tty) _L_FLAG((tty), FLUSHO) +#define L_PENDIN(tty) _L_FLAG((tty), PENDIN) +#define L_IEXTEN(tty) _L_FLAG((tty), IEXTEN) +#define L_EXTPROC(tty) _L_FLAG((tty), EXTPROC) +#define L_NOKERNINFO(tty) _L_FLAG((tty), NOKERNINFO) struct device; struct signal_struct; @@ -388,6 +390,9 @@ void __init n_tty_init(void); static inline void n_tty_init(void) { } #endif +/* n_tty_status.c */ +extern int n_tty_get_status(struct tty_struct *tty, char *msg, size_t *msglen); + /* tty_audit.c */ #ifdef CONFIG_AUDIT void tty_audit_exit(void); -- 2.30.2
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