Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.
On 06. 02. 22, 16:48, Walt Drummond wrote: 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, the local flags ICANON and IEXTEN are enabled and NOKERNINFO is disabled; it is always displayed when TIOCSTAT is called regardless of tty settings. Signed-off-by: Walt Drummond --- It looks like my comments were addressed. However you did not document the chances since v1 here. IOW, [v2] tag missing here. And please add the CCs I added last time, so that relevant people still can comment. thanks, -- js suse labs
Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.
On Sun, Feb 06, 2022 at 07:48:54AM -0800, Walt Drummond wrote:
> 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
This should be documented somewhere, and not buried in a changelog text
like this. Can you also add this information somewhere in the
Documentation/ directory so that people have a hint as to what is going
on here?
> The message is only displayed when the tty has the VSTATUS character
> set, the local flags ICANON and IEXTEN are enabled and NOKERNINFO is
> disabled; it is always displayed when TIOCSTAT is called regardless of
> tty settings.
>
> Signed-off-by: Walt Drummond
> ---
> drivers/tty/Makefile | 2 +-
> drivers/tty/n_tty.c| 34 +++
> drivers/tty/n_tty_status.c | 181 +
> drivers/tty/tty_io.c | 2 +-
> include/linux/tty.h| 5 +
> 5 files changed, 222 insertions(+), 2 deletions(-)
> create mode 100644 drivers/tty/n_tty_status.c
Also, any chance for a test to be added so that we can ensure that this
doesn't change over time in ways that confuse/break people?
Is this now a new user/kernel api format that we must preserve for
forever? Can we add/remove items over time that make sense or are
programs (not just people), going to parse this?
>
> diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
> index a2bd75fbaaa4..3539d7ab77e5 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 64a058a4c63b..fd70efc333d7 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 */
Tabs please.
>
> #undef N_TTY_TRACE
> #ifdef N_TTY_TRACE
> @@ -127,6 +128,8 @@ struct n_tty_data {
> struct mutex output_lock;
> };
>
> +static void 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) && L_IEXTEN(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);
> @@ -2413,6 +2422,26 @@ static unsigned long inq_canon(struct n_tty_data
> *ldata)
> return nr;
> }
>
> +static void n_tty_status(struct tty_struct *tty)
> +{
> + struct n_tty_data *ldata = tty->disc_data;
> + char *msg;
> + size_t len;
> +
> + msg = kzalloc(STATUS_LINE_LEN, GFP_KERNEL);
Please check for memory failures.
> +
> + if (ldata->column != 0) {
> + *msg = '\n';
> + len = n_tty_get_status(tty, msg + 1, STATUS_LINE_LEN - 1);
> + } else {
> + len = n_tty_get_status(tty, msg, STATUS_LINE_LEN);
> + }
> +
> + do_n_tty_write(tty, NULL, msg, len);
> +
> + kfree(msg);
> +}
> +
> static int n_tty_ioctl(struct
[PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.
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, the local flags ICANON and IEXTEN are enabled and NOKERNINFO is
disabled; it is always displayed when TIOCSTAT is called regardless of
tty settings.
Signed-off-by: Walt Drummond
---
drivers/tty/Makefile | 2 +-
drivers/tty/n_tty.c| 34 +++
drivers/tty/n_tty_status.c | 181 +
drivers/tty/tty_io.c | 2 +-
include/linux/tty.h| 5 +
5 files changed, 222 insertions(+), 2 deletions(-)
create mode 100644 drivers/tty/n_tty_status.c
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index a2bd75fbaaa4..3539d7ab77e5 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 64a058a4c63b..fd70efc333d7 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 void 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) && L_IEXTEN(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);
@@ -2413,6 +2422,26 @@ static unsigned long inq_canon(struct n_tty_data *ldata)
return nr;
}
+static void n_tty_status(struct tty_struct *tty)
+{
+ struct n_tty_data *ldata = tty->disc_data;
+ char *msg;
+ size_t len;
+
+ msg = kzalloc(STATUS_LINE_LEN, GFP_KERNEL);
+
+ if (ldata->column != 0) {
+ *msg = '\n';
+ len = n_tty_get_status(tty, msg + 1, STATUS_LINE_LEN - 1);
+ } else {
+ len = n_tty_get_status(tty, msg, STATUS_LINE_LEN);
+ }
+
+ do_n_tty_write(tty, NULL, msg, len);
+
+ kfree(msg);
+}
+
static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
@@ -2430,6 +2459,11 @@ 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);
+ n_tty_status(tty);
+ up_read(&tty->termios_rwsem);
+ return 0;
default:
return n_tty_ioctl_helper(tty, file, cmd, arg);
}
diff --git a/drivers/tty/n_tty_status.c b/drivers/tty/n_tty_status.c
new file mode 100644
index ..f0e053651368
--- /dev/null
+++ b/drivers/tty/n_tty_status.c
@@ -0,0
