[PATCH v2 0/3] vstatus: TTY status message request

[PATCH v2 0/3] vstatus: TTY status message request

[Walt Drummond]

This patchset adds TTY status message request feature to the n_tty
line dicipline.  This feature prints a brief message containing basic
system and process group information to a user's TTY in response to a
new control character in the line dicipline (default Ctrl-T) or the
TIOCSTAT ioctl.  The message contains the current system load, the
name and PID of an interesting process in the forground process group,
it's run time, percent CPU usage and RSS.  An example of this message
is:

  load: 0.31  cmd: sleep 3616843 [sleeping] 0.36r 0.00u 0.00s 0% 696k

This feature is in many other Unix systems, both current and
historical.  In other implementations, this feature would also send
SIGINFO to the process group; this implementation does not.

User API visible changes are limited to:
 - The addition of VSTATUS in termios.c_cc[]
 - The addition of NOKERNINFO bit in termios.l_cflags
 - The addition of the TIOCSTAT ioctl number

None of these changes break the existing kernel api as the termios
structure on all architectures has enough space in the control
character array (.c_cc) for the new character.

Walt Drummond (3):
  vstatus: Allow the n_tty line dicipline to write to a user tty
  status: Add user space API definitions for VSTATUS, NOKERNINFO and
    TIOCSTAT
  vstatus: Display an informational message when the VSTATUS character
    is pressed or TIOCSTAT ioctl is called.

 arch/alpha/include/asm/termios.h         |   4 +-
 arch/alpha/include/uapi/asm/ioctls.h     |   1 +
 arch/alpha/include/uapi/asm/termbits.h   |   2 +
 arch/ia64/include/asm/termios.h          |   4 +-
 arch/ia64/include/uapi/asm/termbits.h    |   2 +
 arch/mips/include/asm/termios.h          |   4 +-
 arch/mips/include/uapi/asm/ioctls.h      |   1 +
 arch/mips/include/uapi/asm/termbits.h    |   2 +
 arch/parisc/include/asm/termios.h        |   4 +-
 arch/parisc/include/uapi/asm/ioctls.h    |   1 +
 arch/parisc/include/uapi/asm/termbits.h  |   2 +
 arch/powerpc/include/asm/termios.h       |   4 +-
 arch/powerpc/include/uapi/asm/ioctls.h   |   2 +
 arch/powerpc/include/uapi/asm/termbits.h |   2 +
 arch/s390/include/asm/termios.h          |   4 +-
 arch/sh/include/uapi/asm/ioctls.h        |   1 +
 arch/sparc/include/uapi/asm/ioctls.h     |   1 +
 arch/sparc/include/uapi/asm/termbits.h   |   2 +
 arch/xtensa/include/uapi/asm/ioctls.h    |   1 +
 drivers/tty/Makefile                     |   2 +-
 drivers/tty/n_tty.c                      | 103 +++++++++----
 drivers/tty/n_tty_status.c               | 181 +++++++++++++++++++++++
 drivers/tty/tty_io.c                     |   2 +-
 include/asm-generic/termios.h            |   4 +-
 include/linux/tty.h                      |   7 +-
 include/uapi/asm-generic/ioctls.h        |   1 +
 include/uapi/asm-generic/termbits.h      |   2 +
 27 files changed, 301 insertions(+), 45 deletions(-)
 create mode 100644 drivers/tty/n_tty_status.c

-- 
2.30.2

[PATCH v2 0/3] vstatus: TTY status message request

[Walt Drummond]

This patchset adds TTY status message request feature to the n_tty
line dicipline.  This feature prints a brief message containing basic
system and process group information to a user's TTY in response to a
new control character in the line dicipline (default Ctrl-T) or the
TIOCSTAT ioctl.  The message contains the current system load, the
name and PID of an interesting process in the forground process group,
it's run time, percent CPU usage and RSS.  An example of this message
is:

  load: 0.31  cmd: sleep 3616843 [sleeping] 0.36r 0.00u 0.00s 0% 696k

This feature is in many other Unix systems, both current and
historical.  In other implementations, this feature would also send
SIGINFO to the process group; this implementation does not.

User API visible changes are limited to:
 - The addition of VSTATUS in termios.c_cc[]
 - The addition of NOKERNINFO bit in termios.l_cflags
 - The addition of the TIOCSTAT ioctl number

None of these changes break the existing kernel api as the termios
structure on all architectures has enough space in the control
character array (.c_cc) for the new character.

Walt Drummond (3):
  vstatus: Allow the n_tty line dicipline to write to a user tty
  status: Add user space API definitions for VSTATUS, NOKERNINFO and
    TIOCSTAT
  vstatus: Display an informational message when the VSTATUS character
    is pressed or TIOCSTAT ioctl is called.

 arch/alpha/include/asm/termios.h         |   4 +-
 arch/alpha/include/uapi/asm/ioctls.h     |   1 +
 arch/alpha/include/uapi/asm/termbits.h   |   2 +
 arch/ia64/include/asm/termios.h          |   4 +-
 arch/ia64/include/uapi/asm/termbits.h    |   2 +
 arch/mips/include/asm/termios.h          |   4 +-
 arch/mips/include/uapi/asm/ioctls.h      |   1 +
 arch/mips/include/uapi/asm/termbits.h    |   2 +
 arch/parisc/include/asm/termios.h        |   4 +-
 arch/parisc/include/uapi/asm/ioctls.h    |   1 +
 arch/parisc/include/uapi/asm/termbits.h  |   2 +
 arch/powerpc/include/asm/termios.h       |   4 +-
 arch/powerpc/include/uapi/asm/ioctls.h   |   2 +
 arch/powerpc/include/uapi/asm/termbits.h |   2 +
 arch/s390/include/asm/termios.h          |   4 +-
 arch/sh/include/uapi/asm/ioctls.h        |   1 +
 arch/sparc/include/uapi/asm/ioctls.h     |   1 +
 arch/sparc/include/uapi/asm/termbits.h   |   2 +
 arch/xtensa/include/uapi/asm/ioctls.h    |   1 +
 drivers/tty/Makefile                     |   2 +-
 drivers/tty/n_tty.c                      | 103 +++++++++----
 drivers/tty/n_tty_status.c               | 181 +++++++++++++++++++++++
 drivers/tty/tty_io.c                     |   2 +-
 include/asm-generic/termios.h            |   4 +-
 include/linux/tty.h                      |   7 +-
 include/uapi/asm-generic/ioctls.h        |   1 +
 include/uapi/asm-generic/termbits.h      |   2 +
 27 files changed, 301 insertions(+), 45 deletions(-)
 create mode 100644 drivers/tty/n_tty_status.c

-- 
2.30.2

[PATCH v2 0/3] vstatus: TTY status message request

[Walt Drummond]

This patchset adds TTY status message request feature to the n_tty
line dicipline.  This feature prints a brief message containing basic
system and process group information to a user's TTY in response to a
new control character in the line dicipline (default Ctrl-T) or the
TIOCSTAT ioctl.  The message contains the current system load, the
name and PID of an interesting process in the forground process group,
it's run time, percent CPU usage and RSS.  An example of this message
is:

  load: 0.31  cmd: sleep 3616843 [sleeping] 0.36r 0.00u 0.00s 0% 696k

This feature is in many other Unix systems, both current and
historical.  In other implementations, this feature would also send
SIGINFO to the process group; this implementation does not.

User API visible changes are limited to:
 - The addition of VSTATUS in termios.c_cc[]
 - The addition of NOKERNINFO bit in termios.l_cflags
 - The addition of the TIOCSTAT ioctl number

None of these changes break the existing kernel api as the termios
structure on all architectures has enough space in the control
character array (.c_cc) for the new character.

Walt Drummond (3):
  vstatus: Allow the n_tty line dicipline to write to a user tty
  status: Add user space API definitions for VSTATUS, NOKERNINFO and
    TIOCSTAT
  vstatus: Display an informational message when the VSTATUS character
    is pressed or TIOCSTAT ioctl is called.

 arch/alpha/include/asm/termios.h         |   4 +-
 arch/alpha/include/uapi/asm/ioctls.h     |   1 +
 arch/alpha/include/uapi/asm/termbits.h   |   2 +
 arch/ia64/include/asm/termios.h          |   4 +-
 arch/ia64/include/uapi/asm/termbits.h    |   2 +
 arch/mips/include/asm/termios.h          |   4 +-
 arch/mips/include/uapi/asm/ioctls.h      |   1 +
 arch/mips/include/uapi/asm/termbits.h    |   2 +
 arch/parisc/include/asm/termios.h        |   4 +-
 arch/parisc/include/uapi/asm/ioctls.h    |   1 +
 arch/parisc/include/uapi/asm/termbits.h  |   2 +
 arch/powerpc/include/asm/termios.h       |   4 +-
 arch/powerpc/include/uapi/asm/ioctls.h   |   2 +
 arch/powerpc/include/uapi/asm/termbits.h |   2 +
 arch/s390/include/asm/termios.h          |   4 +-
 arch/sh/include/uapi/asm/ioctls.h        |   1 +
 arch/sparc/include/uapi/asm/ioctls.h     |   1 +
 arch/sparc/include/uapi/asm/termbits.h   |   2 +
 arch/xtensa/include/uapi/asm/ioctls.h    |   1 +
 drivers/tty/Makefile                     |   2 +-
 drivers/tty/n_tty.c                      | 103 +++++++++----
 drivers/tty/n_tty_status.c               | 181 +++++++++++++++++++++++
 drivers/tty/tty_io.c                     |   2 +-
 include/asm-generic/termios.h            |   4 +-
 include/linux/tty.h                      |   7 +-
 include/uapi/asm-generic/ioctls.h        |   1 +
 include/uapi/asm-generic/termbits.h      |   2 +
 27 files changed, 301 insertions(+), 45 deletions(-)
 create mode 100644 drivers/tty/n_tty_status.c

-- 
2.30.2

[PATCH v2 1/3] vstatus: Allow the n_tty line dicipline to write to a user tty

[Walt Drummond]

Refactor the implementation of n_tty_write() into do_n_tty_write(),
and change n_tty_write() to call do_n_tty_write() after acquiring
tty.termios_rwsem.

This allows the n_tty line dicipline to write to a user tty via
do_n_tty_write() when already holding tty.termios_rwsem.

Signed-off-by: Walt Drummond <walt@drummond.us>
---
 drivers/tty/n_tty.c | 69 +++++++++++++++++++++++++++------------------
 include/linux/tty.h |  2 +-
 2 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 0ec93f1a61f5..64a058a4c63b 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2231,45 +2231,24 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 	return retval;
 }
 
-/**
- *	n_tty_write		-	write function for tty
- *	@tty: tty device
- *	@file: file object
- *	@buf: userspace buffer pointer
- *	@nr: size of I/O
- *
- *	Write function of the terminal device.  This is serialized with
- *	respect to other write callers but not to termios changes, reads
- *	and other such events.  Since the receive code will echo characters,
- *	thus calling driver write methods, the output_lock is used in
- *	the output processing functions called here as well as in the
- *	echo processing function to protect the column state and space
- *	left in the buffer.
- *
- *	This code must be sure never to sleep through a hangup.
- *
- *	Locking: output_lock to protect column state and space left
- *		 (note that the process_output*() functions take this
- *		  lock themselves)
- */
-
-static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
-			   const unsigned char *buf, size_t nr)
+static ssize_t do_n_tty_write(struct tty_struct *tty, struct file *file,
+			      const unsigned char *buf, size_t nr)
 {
 	const unsigned char *b = buf;
 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 	int c;
 	ssize_t retval = 0;
 
+	lockdep_assert_held_read(&tty->termios_rwsem);
+
 	/* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
-	if (L_TOSTOP(tty) && file->f_op->write_iter != redirected_tty_write) {
+	if (L_TOSTOP(tty) &&
+	    !(file && file->f_op->write_iter != redirected_tty_write)) {
 		retval = tty_check_change(tty);
 		if (retval)
 			return retval;
 	}
 
-	down_read(&tty->termios_rwsem);
-
 	/* Write out any echoed characters that are still pending */
 	process_echoes(tty);
 
@@ -2336,10 +2315,44 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
 	remove_wait_queue(&tty->write_wait, &wait);
 	if (nr && tty->fasync)
 		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-	up_read(&tty->termios_rwsem);
+
 	return (b - buf) ? b - buf : retval;
 }
 
+/**
+ *	n_tty_write		-	write function for tty
+ *	@tty: tty device
+ *	@file: file object
+ *	@buf: userspace buffer pointer
+ *	@nr: size of I/O
+ *
+ *	Write function of the terminal device.  This is serialized with
+ *	respect to other write callers but not to termios changes, reads
+ *	and other such events.  Since the receive code will echo characters,
+ *	thus calling driver write methods, the output_lock is used in
+ *	the output processing functions called here as well as in the
+ *	echo processing function to protect the column state and space
+ *	left in the buffer.
+ *
+ *	This code must be sure never to sleep through a hangup.
+ *
+ *	Locking: output_lock to protect column state and space left
+ *		 (note that the process_output*() functions take this
+ *		  lock themselves)
+ */
+
+static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+			   const unsigned char *buf, size_t nr)
+{
+	ssize_t retval = 0;
+
+	down_read(&tty->termios_rwsem);
+	retval = do_n_tty_write(tty, file, buf, nr);
+	up_read(&tty->termios_rwsem);
+
+	return retval;
+}
+
 /**
  *	n_tty_poll		-	poll method for N_TTY
  *	@tty: terminal device
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 168e57e40bbb..cbe5d535a69d 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -237,7 +237,7 @@ struct tty_file_private {
 
 static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
 {
-	return file->f_flags & O_NONBLOCK ||
+	return (file && file->f_flags & O_NONBLOCK) ||
 		test_bit(TTY_LDISC_CHANGING, &tty->flags);
 }
 
-- 
2.30.2

[PATCH v2 1/3] vstatus: Allow the n_tty line dicipline to write to a user tty

[Walt Drummond]

Refactor the implementation of n_tty_write() into do_n_tty_write(),
and change n_tty_write() to call do_n_tty_write() after acquiring
tty.termios_rwsem.

This allows the n_tty line dicipline to write to a user tty via
do_n_tty_write() when already holding tty.termios_rwsem.

Signed-off-by: Walt Drummond <walt@drummond.us>
---
 drivers/tty/n_tty.c | 69 +++++++++++++++++++++++++++------------------
 include/linux/tty.h |  2 +-
 2 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 0ec93f1a61f5..64a058a4c63b 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2231,45 +2231,24 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 	return retval;
 }
 
-/**
- *	n_tty_write		-	write function for tty
- *	@tty: tty device
- *	@file: file object
- *	@buf: userspace buffer pointer
- *	@nr: size of I/O
- *
- *	Write function of the terminal device.  This is serialized with
- *	respect to other write callers but not to termios changes, reads
- *	and other such events.  Since the receive code will echo characters,
- *	thus calling driver write methods, the output_lock is used in
- *	the output processing functions called here as well as in the
- *	echo processing function to protect the column state and space
- *	left in the buffer.
- *
- *	This code must be sure never to sleep through a hangup.
- *
- *	Locking: output_lock to protect column state and space left
- *		 (note that the process_output*() functions take this
- *		  lock themselves)
- */
-
-static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
-			   const unsigned char *buf, size_t nr)
+static ssize_t do_n_tty_write(struct tty_struct *tty, struct file *file,
+			      const unsigned char *buf, size_t nr)
 {
 	const unsigned char *b = buf;
 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 	int c;
 	ssize_t retval = 0;
 
+	lockdep_assert_held_read(&tty->termios_rwsem);
+
 	/* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
-	if (L_TOSTOP(tty) && file->f_op->write_iter != redirected_tty_write) {
+	if (L_TOSTOP(tty) &&
+	    !(file && file->f_op->write_iter != redirected_tty_write)) {
 		retval = tty_check_change(tty);
 		if (retval)
 			return retval;
 	}
 
-	down_read(&tty->termios_rwsem);
-
 	/* Write out any echoed characters that are still pending */
 	process_echoes(tty);
 
@@ -2336,10 +2315,44 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
 	remove_wait_queue(&tty->write_wait, &wait);
 	if (nr && tty->fasync)
 		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-	up_read(&tty->termios_rwsem);
+
 	return (b - buf) ? b - buf : retval;
 }
 
+/**
+ *	n_tty_write		-	write function for tty
+ *	@tty: tty device
+ *	@file: file object
+ *	@buf: userspace buffer pointer
+ *	@nr: size of I/O
+ *
+ *	Write function of the terminal device.  This is serialized with
+ *	respect to other write callers but not to termios changes, reads
+ *	and other such events.  Since the receive code will echo characters,
+ *	thus calling driver write methods, the output_lock is used in
+ *	the output processing functions called here as well as in the
+ *	echo processing function to protect the column state and space
+ *	left in the buffer.
+ *
+ *	This code must be sure never to sleep through a hangup.
+ *
+ *	Locking: output_lock to protect column state and space left
+ *		 (note that the process_output*() functions take this
+ *		  lock themselves)
+ */
+
+static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+			   const unsigned char *buf, size_t nr)
+{
+	ssize_t retval = 0;
+
+	down_read(&tty->termios_rwsem);
+	retval = do_n_tty_write(tty, file, buf, nr);
+	up_read(&tty->termios_rwsem);
+
+	return retval;
+}
+
 /**
  *	n_tty_poll		-	poll method for N_TTY
  *	@tty: terminal device
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 168e57e40bbb..cbe5d535a69d 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -237,7 +237,7 @@ struct tty_file_private {
 
 static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
 {
-	return file->f_flags & O_NONBLOCK ||
+	return (file && file->f_flags & O_NONBLOCK) ||
 		test_bit(TTY_LDISC_CHANGING, &tty->flags);
 }
 
-- 
2.30.2

[PATCH v2 1/3] vstatus: Allow the n_tty line dicipline to write to a user tty

[Walt Drummond]

Refactor the implementation of n_tty_write() into do_n_tty_write(),
and change n_tty_write() to call do_n_tty_write() after acquiring
tty.termios_rwsem.

This allows the n_tty line dicipline to write to a user tty via
do_n_tty_write() when already holding tty.termios_rwsem.

Signed-off-by: Walt Drummond <walt@drummond.us>
---
 drivers/tty/n_tty.c | 69 +++++++++++++++++++++++++++------------------
 include/linux/tty.h |  2 +-
 2 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 0ec93f1a61f5..64a058a4c63b 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2231,45 +2231,24 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 	return retval;
 }
 
-/**
- *	n_tty_write		-	write function for tty
- *	@tty: tty device
- *	@file: file object
- *	@buf: userspace buffer pointer
- *	@nr: size of I/O
- *
- *	Write function of the terminal device.  This is serialized with
- *	respect to other write callers but not to termios changes, reads
- *	and other such events.  Since the receive code will echo characters,
- *	thus calling driver write methods, the output_lock is used in
- *	the output processing functions called here as well as in the
- *	echo processing function to protect the column state and space
- *	left in the buffer.
- *
- *	This code must be sure never to sleep through a hangup.
- *
- *	Locking: output_lock to protect column state and space left
- *		 (note that the process_output*() functions take this
- *		  lock themselves)
- */
-
-static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
-			   const unsigned char *buf, size_t nr)
+static ssize_t do_n_tty_write(struct tty_struct *tty, struct file *file,
+			      const unsigned char *buf, size_t nr)
 {
 	const unsigned char *b = buf;
 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 	int c;
 	ssize_t retval = 0;
 
+	lockdep_assert_held_read(&tty->termios_rwsem);
+
 	/* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
-	if (L_TOSTOP(tty) && file->f_op->write_iter != redirected_tty_write) {
+	if (L_TOSTOP(tty) &&
+	    !(file && file->f_op->write_iter != redirected_tty_write)) {
 		retval = tty_check_change(tty);
 		if (retval)
 			return retval;
 	}
 
-	down_read(&tty->termios_rwsem);
-
 	/* Write out any echoed characters that are still pending */
 	process_echoes(tty);
 
@@ -2336,10 +2315,44 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
 	remove_wait_queue(&tty->write_wait, &wait);
 	if (nr && tty->fasync)
 		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-	up_read(&tty->termios_rwsem);
+
 	return (b - buf) ? b - buf : retval;
 }
 
+/**
+ *	n_tty_write		-	write function for tty
+ *	@tty: tty device
+ *	@file: file object
+ *	@buf: userspace buffer pointer
+ *	@nr: size of I/O
+ *
+ *	Write function of the terminal device.  This is serialized with
+ *	respect to other write callers but not to termios changes, reads
+ *	and other such events.  Since the receive code will echo characters,
+ *	thus calling driver write methods, the output_lock is used in
+ *	the output processing functions called here as well as in the
+ *	echo processing function to protect the column state and space
+ *	left in the buffer.
+ *
+ *	This code must be sure never to sleep through a hangup.
+ *
+ *	Locking: output_lock to protect column state and space left
+ *		 (note that the process_output*() functions take this
+ *		  lock themselves)
+ */
+
+static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+			   const unsigned char *buf, size_t nr)
+{
+	ssize_t retval = 0;
+
+	down_read(&tty->termios_rwsem);
+	retval = do_n_tty_write(tty, file, buf, nr);
+	up_read(&tty->termios_rwsem);
+
+	return retval;
+}
+
 /**
  *	n_tty_poll		-	poll method for N_TTY
  *	@tty: terminal device
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 168e57e40bbb..cbe5d535a69d 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -237,7 +237,7 @@ struct tty_file_private {
 
 static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
 {
-	return file->f_flags & O_NONBLOCK ||
+	return (file && file->f_flags & O_NONBLOCK) ||
 		test_bit(TTY_LDISC_CHANGING, &tty->flags);
 }
 
-- 
2.30.2

[PATCH v2 2/3] status: Add user space API definitions for VSTATUS, NOKERNINFO and TIOCSTAT

[Walt Drummond]

Add definitions for the VSTATUS control character, and the NOKERNINFO
local control flag in the termios struct, and add an ioctl number for
the ioctl TIOCSTAT.  Also add a default VSTATUS character (Ctrl-T)
default valuses in termios.c_cc.  Do this for all architectures.

Signed-off-by: Walt Drummond <walt@drummond.us>
---
 arch/alpha/include/asm/termios.h         | 4 ++--
 arch/alpha/include/uapi/asm/ioctls.h     | 1 +
 arch/alpha/include/uapi/asm/termbits.h   | 2 ++
 arch/ia64/include/asm/termios.h          | 4 ++--
 arch/ia64/include/uapi/asm/termbits.h    | 2 ++
 arch/mips/include/asm/termios.h          | 4 ++--
 arch/mips/include/uapi/asm/ioctls.h      | 1 +
 arch/mips/include/uapi/asm/termbits.h    | 2 ++
 arch/parisc/include/asm/termios.h        | 4 ++--
 arch/parisc/include/uapi/asm/ioctls.h    | 1 +
 arch/parisc/include/uapi/asm/termbits.h  | 2 ++
 arch/powerpc/include/asm/termios.h       | 4 ++--
 arch/powerpc/include/uapi/asm/ioctls.h   | 2 ++
 arch/powerpc/include/uapi/asm/termbits.h | 2 ++
 arch/s390/include/asm/termios.h          | 4 ++--
 arch/sh/include/uapi/asm/ioctls.h        | 1 +
 arch/sparc/include/uapi/asm/ioctls.h     | 1 +
 arch/sparc/include/uapi/asm/termbits.h   | 2 ++
 arch/xtensa/include/uapi/asm/ioctls.h    | 1 +
 include/asm-generic/termios.h            | 4 ++--
 include/uapi/asm-generic/ioctls.h        | 1 +
 include/uapi/asm-generic/termbits.h      | 2 ++
 22 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
index b7c77bb1bfd2..d28ddc649286 100644
--- a/arch/alpha/include/asm/termios.h
+++ b/arch/alpha/include/asm/termios.h
@@ -8,9 +8,9 @@
 	werase=^W	kill=^U		reprint=^R	sxtc=\0
 	intr=^C		quit=^\		susp=^Z		<OSF/1 VDSUSP>
 	start=^Q	stop=^S		lnext=^V	discard=^U
-	vmin=\1		vtime=\0
+	vmin=\1		vtime=\0        status=^T
 */
-#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000"
+#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
index 971311605288..70fdeab2b5f2 100644
--- a/arch/alpha/include/uapi/asm/ioctls.h
+++ b/arch/alpha/include/uapi/asm/ioctls.h
@@ -124,5 +124,6 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 
 #endif /* _ASM_ALPHA_IOCTLS_H */
diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
index 4575ba34a0ea..9a1b9aa92d29 100644
--- a/arch/alpha/include/uapi/asm/termbits.h
+++ b/arch/alpha/include/uapi/asm/termbits.h
@@ -70,6 +70,7 @@ struct ktermios {
 #define VDISCARD 15
 #define VMIN 16
 #define VTIME 17
+#define VSTATUS 18
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -203,6 +204,7 @@ struct ktermios {
 #define PENDIN	0x20000000
 #define IEXTEN	0x00000400
 #define EXTPROC	0x10000000
+#define NOKERNINFO 0x40000000
 
 /* Values for the ACTION argument to `tcflow'.  */
 #define	TCOOFF		0
diff --git a/arch/ia64/include/asm/termios.h b/arch/ia64/include/asm/termios.h
index 589c026444cc..40e83f9b6ead 100644
--- a/arch/ia64/include/asm/termios.h
+++ b/arch/ia64/include/asm/termios.h
@@ -15,9 +15,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/ia64/include/uapi/asm/termbits.h b/arch/ia64/include/uapi/asm/termbits.h
index 000a1a297c75..0b5fea00343b 100644
--- a/arch/ia64/include/uapi/asm/termbits.h
+++ b/arch/ia64/include/uapi/asm/termbits.h
@@ -67,6 +67,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -189,6 +190,7 @@ struct ktermios {
 #define PENDIN	0040000
 #define IEXTEN	0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
diff --git a/arch/mips/include/asm/termios.h b/arch/mips/include/asm/termios.h
index bc29eeacc55a..04729018d882 100644
--- a/arch/mips/include/asm/termios.h
+++ b/arch/mips/include/asm/termios.h
@@ -17,9 +17,9 @@
  *	vmin=\1		vtime=\0	eol2=\0		swtc=\0
  *	start=^Q	stop=^S		susp=^Z		vdsusp=
  *	reprint=^R	discard=^U	werase=^W	lnext=^V
- *	eof=^D		eol=\0
+ *	eof=^D		eol=\0          status=^T
  */
-#define INIT_C_CC "\003\034\177\025\1\0\0\0\021\023\032\0\022\017\027\026\004\0"
+#define INIT_C_CC "\003\034\177\025\1\0\0\0\021\023\032\0\022\017\027\026\004\0\024"
 
 #include <linux/string.h>
 
diff --git a/arch/mips/include/uapi/asm/ioctls.h b/arch/mips/include/uapi/asm/ioctls.h
index 16aa8a766aec..f9ec28ac38db 100644
--- a/arch/mips/include/uapi/asm/ioctls.h
+++ b/arch/mips/include/uapi/asm/ioctls.h
@@ -115,5 +115,6 @@
 #define TIOCSERSETMULTI 0x5490 /* Set multiport config */
 #define TIOCMIWAIT	0x5491 /* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x5492 /* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x93) /* display process group stats on tty */
 
 #endif /* __ASM_IOCTLS_H */
diff --git a/arch/mips/include/uapi/asm/termbits.h b/arch/mips/include/uapi/asm/termbits.h
index dfeffba729b7..a10be13a6f7b 100644
--- a/arch/mips/include/uapi/asm/termbits.h
+++ b/arch/mips/include/uapi/asm/termbits.h
@@ -78,6 +78,7 @@ struct ktermios {
 #define VLNEXT		15		/* Literal-next character [IEXTEN].  */
 #define VEOF		16		/* End-of-file character [ICANON].  */
 #define VEOL		17		/* End-of-line character [ICANON].  */
+#define VSTATUS         18
 
 /* c_iflag bits */
 #define IGNBRK	0000001		/* Ignore break condition.  */
@@ -205,6 +206,7 @@ struct ktermios {
 #define TOSTOP	0100000		/* Send SIGTTOU for background output.	*/
 #define ITOSTOP TOSTOP
 #define EXTPROC 0200000		/* External processing on pty */
+#define NOKERNINFO 0400000	/* Disable kernel status message */
 
 /* ioctl (fd, TIOCSERGETLSR, &result) where result may be as below */
 #define TIOCSER_TEMT	0x01	/* Transmitter physically empty */
diff --git a/arch/parisc/include/asm/termios.h b/arch/parisc/include/asm/termios.h
index cded9dc90c1b..63c6c7edb0ff 100644
--- a/arch/parisc/include/asm/termios.h
+++ b/arch/parisc/include/asm/termios.h
@@ -9,9 +9,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/parisc/include/uapi/asm/ioctls.h b/arch/parisc/include/uapi/asm/ioctls.h
index 82d1148c6379..1ac156dd8209 100644
--- a/arch/parisc/include/uapi/asm/ioctls.h
+++ b/arch/parisc/include/uapi/asm/ioctls.h
@@ -80,6 +80,7 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 #define FIOQSIZE	0x5460	/* Get exact space used by quota */
 
 #define TIOCSTART	0x5461
diff --git a/arch/parisc/include/uapi/asm/termbits.h b/arch/parisc/include/uapi/asm/termbits.h
index 40e920f8d683..b449d8ea1c00 100644
--- a/arch/parisc/include/uapi/asm/termbits.h
+++ b/arch/parisc/include/uapi/asm/termbits.h
@@ -58,6 +58,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 
 /* c_iflag bits */
@@ -182,6 +183,7 @@ struct ktermios {
 #define PENDIN  0040000
 #define IEXTEN  0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
diff --git a/arch/powerpc/include/asm/termios.h b/arch/powerpc/include/asm/termios.h
index 205de8f8a9d3..e5381c8f86f0 100644
--- a/arch/powerpc/include/asm/termios.h
+++ b/arch/powerpc/include/asm/termios.h
@@ -10,8 +10,8 @@
 
 #include <uapi/asm/termios.h>
 
-/*                   ^C  ^\ del  ^U  ^D   1   0   0   0   0  ^W  ^R  ^Z  ^Q  ^S  ^V  ^U  */
-#define INIT_C_CC "\003\034\177\025\004\001\000\000\000\000\027\022\032\021\023\026\025" 
+/*                   ^C  ^\ del  ^U  ^D   1   0   0   0   0  ^W  ^R  ^Z  ^Q  ^S  ^V  ^U  ^T */
+#define INIT_C_CC "\003\034\177\025\004\001\000\000\000\000\027\022\032\021\023\026\025\024"
 
 #include <asm-generic/termios-base.h>
 
diff --git a/arch/powerpc/include/uapi/asm/ioctls.h b/arch/powerpc/include/uapi/asm/ioctls.h
index 2c145da3b774..0a0755863500 100644
--- a/arch/powerpc/include/uapi/asm/ioctls.h
+++ b/arch/powerpc/include/uapi/asm/ioctls.h
@@ -120,4 +120,6 @@
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
 
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
+
 #endif	/* _ASM_POWERPC_IOCTLS_H */
diff --git a/arch/powerpc/include/uapi/asm/termbits.h b/arch/powerpc/include/uapi/asm/termbits.h
index ed18bc61f63d..50d787d95c91 100644
--- a/arch/powerpc/include/uapi/asm/termbits.h
+++ b/arch/powerpc/include/uapi/asm/termbits.h
@@ -62,6 +62,7 @@ struct ktermios {
 #define VSTOP		14
 #define VLNEXT		15
 #define VDISCARD	16
+#define VSTATUS		17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -191,6 +192,7 @@ struct ktermios {
 #define PENDIN	0x20000000
 #define IEXTEN	0x00000400
 #define EXTPROC	0x10000000
+#define NOKERNINFO 0x40000000
 
 /* Values for the ACTION argument to `tcflow'.  */
 #define	TCOOFF		0
diff --git a/arch/s390/include/asm/termios.h b/arch/s390/include/asm/termios.h
index 46fa3020b41e..8d2017f4905d 100644
--- a/arch/s390/include/asm/termios.h
+++ b/arch/s390/include/asm/termios.h
@@ -14,9 +14,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         vstatus=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 #define user_termios_to_kernel_termios(k, u) copy_from_user(k, u, sizeof(struct termios2))
 #define kernel_termios_to_user_termios(u, k) copy_to_user(u, k, sizeof(struct termios2))
diff --git a/arch/sh/include/uapi/asm/ioctls.h b/arch/sh/include/uapi/asm/ioctls.h
index 11866d4f60e1..fefef10922ec 100644
--- a/arch/sh/include/uapi/asm/ioctls.h
+++ b/arch/sh/include/uapi/asm/ioctls.h
@@ -112,5 +112,6 @@
 
 #define TIOCMIWAIT	_IO('T', 92) /* 0x545C */	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5F)	/* display process group stats on tty */
 
 #endif /* __ASM_SH_IOCTLS_H */
diff --git a/arch/sparc/include/uapi/asm/ioctls.h b/arch/sparc/include/uapi/asm/ioctls.h
index 7fd2f5873c9e..9819090bd850 100644
--- a/arch/sparc/include/uapi/asm/ioctls.h
+++ b/arch/sparc/include/uapi/asm/ioctls.h
@@ -124,6 +124,7 @@
 #define TIOCSERSETMULTI 0x545B /* Set multiport config */
 #define TIOCMIWAIT	0x545C /* Wait for change on serial input line(s) */
 #define TIOCGICOUNT	0x545D /* Read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E) /* Display process group stats on tty */
 
 /* Kernel definitions */
 
diff --git a/arch/sparc/include/uapi/asm/termbits.h b/arch/sparc/include/uapi/asm/termbits.h
index ce5ad5d0f105..b8441ce42278 100644
--- a/arch/sparc/include/uapi/asm/termbits.h
+++ b/arch/sparc/include/uapi/asm/termbits.h
@@ -80,6 +80,7 @@ struct ktermios {
 #define VDISCARD 13
 #define VWERASE  14
 #define VLNEXT   15
+#define VSTATUS  16
 
 /* Kernel keeps vmin/vtime separated, user apps assume vmin/vtime is
  * shared with eof/eol
@@ -224,6 +225,7 @@ struct ktermios {
 #define PENDIN	0x00004000
 #define IEXTEN	0x00008000
 #define EXTPROC	0x00010000
+#define NOKERNINFO 0x00020000
 
 /* modem lines */
 #define TIOCM_LE	0x001
diff --git a/arch/xtensa/include/uapi/asm/ioctls.h b/arch/xtensa/include/uapi/asm/ioctls.h
index 6d4a87296c95..f92fb8e5b2a5 100644
--- a/arch/xtensa/include/uapi/asm/ioctls.h
+++ b/arch/xtensa/include/uapi/asm/ioctls.h
@@ -126,5 +126,6 @@
 
 #define TIOCMIWAIT	_IO('T', 92) /* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 
 #endif /* _XTENSA_IOCTLS_H */
diff --git a/include/asm-generic/termios.h b/include/asm-generic/termios.h
index b1398d0d4a1d..9b080e1a82d4 100644
--- a/include/asm-generic/termios.h
+++ b/include/asm-generic/termios.h
@@ -10,9 +10,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/include/uapi/asm-generic/ioctls.h b/include/uapi/asm-generic/ioctls.h
index cdc9f4ca8c27..02ceb990ce9b 100644
--- a/include/uapi/asm-generic/ioctls.h
+++ b/include/uapi/asm-generic/ioctls.h
@@ -97,6 +97,7 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT        _IO('T', 0x5E)	/* display process group stats on tty */
 
 /*
  * Some arches already define FIOQSIZE due to a historical
diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
index 2fbaf9ae89dd..6219803d6f4d 100644
--- a/include/uapi/asm-generic/termbits.h
+++ b/include/uapi/asm-generic/termbits.h
@@ -58,6 +58,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -180,6 +181,7 @@ struct ktermios {
 #define PENDIN	0040000
 #define IEXTEN	0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
-- 
2.30.2

[PATCH v2 2/3] status: Add user space API definitions for VSTATUS, NOKERNINFO and TIOCSTAT

[Walt Drummond]

Add definitions for the VSTATUS control character, and the NOKERNINFO
local control flag in the termios struct, and add an ioctl number for
the ioctl TIOCSTAT.  Also add a default VSTATUS character (Ctrl-T)
default valuses in termios.c_cc.  Do this for all architectures.

Signed-off-by: Walt Drummond <walt@drummond.us>
---
 arch/alpha/include/asm/termios.h         | 4 ++--
 arch/alpha/include/uapi/asm/ioctls.h     | 1 +
 arch/alpha/include/uapi/asm/termbits.h   | 2 ++
 arch/ia64/include/asm/termios.h          | 4 ++--
 arch/ia64/include/uapi/asm/termbits.h    | 2 ++
 arch/mips/include/asm/termios.h          | 4 ++--
 arch/mips/include/uapi/asm/ioctls.h      | 1 +
 arch/mips/include/uapi/asm/termbits.h    | 2 ++
 arch/parisc/include/asm/termios.h        | 4 ++--
 arch/parisc/include/uapi/asm/ioctls.h    | 1 +
 arch/parisc/include/uapi/asm/termbits.h  | 2 ++
 arch/powerpc/include/asm/termios.h       | 4 ++--
 arch/powerpc/include/uapi/asm/ioctls.h   | 2 ++
 arch/powerpc/include/uapi/asm/termbits.h | 2 ++
 arch/s390/include/asm/termios.h          | 4 ++--
 arch/sh/include/uapi/asm/ioctls.h        | 1 +
 arch/sparc/include/uapi/asm/ioctls.h     | 1 +
 arch/sparc/include/uapi/asm/termbits.h   | 2 ++
 arch/xtensa/include/uapi/asm/ioctls.h    | 1 +
 include/asm-generic/termios.h            | 4 ++--
 include/uapi/asm-generic/ioctls.h        | 1 +
 include/uapi/asm-generic/termbits.h      | 2 ++
 22 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
index b7c77bb1bfd2..d28ddc649286 100644
--- a/arch/alpha/include/asm/termios.h
+++ b/arch/alpha/include/asm/termios.h
@@ -8,9 +8,9 @@
 	werase=^W	kill=^U		reprint=^R	sxtc=\0
 	intr=^C		quit=^\		susp=^Z		<OSF/1 VDSUSP>
 	start=^Q	stop=^S		lnext=^V	discard=^U
-	vmin=\1		vtime=\0
+	vmin=\1		vtime=\0        status=^T
 */
-#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000"
+#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
index 971311605288..70fdeab2b5f2 100644
--- a/arch/alpha/include/uapi/asm/ioctls.h
+++ b/arch/alpha/include/uapi/asm/ioctls.h
@@ -124,5 +124,6 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 
 #endif /* _ASM_ALPHA_IOCTLS_H */
diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
index 4575ba34a0ea..9a1b9aa92d29 100644
--- a/arch/alpha/include/uapi/asm/termbits.h
+++ b/arch/alpha/include/uapi/asm/termbits.h
@@ -70,6 +70,7 @@ struct ktermios {
 #define VDISCARD 15
 #define VMIN 16
 #define VTIME 17
+#define VSTATUS 18
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -203,6 +204,7 @@ struct ktermios {
 #define PENDIN	0x20000000
 #define IEXTEN	0x00000400
 #define EXTPROC	0x10000000
+#define NOKERNINFO 0x40000000
 
 /* Values for the ACTION argument to `tcflow'.  */
 #define	TCOOFF		0
diff --git a/arch/ia64/include/asm/termios.h b/arch/ia64/include/asm/termios.h
index 589c026444cc..40e83f9b6ead 100644
--- a/arch/ia64/include/asm/termios.h
+++ b/arch/ia64/include/asm/termios.h
@@ -15,9 +15,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/ia64/include/uapi/asm/termbits.h b/arch/ia64/include/uapi/asm/termbits.h
index 000a1a297c75..0b5fea00343b 100644
--- a/arch/ia64/include/uapi/asm/termbits.h
+++ b/arch/ia64/include/uapi/asm/termbits.h
@@ -67,6 +67,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -189,6 +190,7 @@ struct ktermios {
 #define PENDIN	0040000
 #define IEXTEN	0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
diff --git a/arch/mips/include/asm/termios.h b/arch/mips/include/asm/termios.h
index bc29eeacc55a..04729018d882 100644
--- a/arch/mips/include/asm/termios.h
+++ b/arch/mips/include/asm/termios.h
@@ -17,9 +17,9 @@
  *	vmin=\1		vtime=\0	eol2=\0		swtc=\0
  *	start=^Q	stop=^S		susp=^Z		vdsusp=
  *	reprint=^R	discard=^U	werase=^W	lnext=^V
- *	eof=^D		eol=\0
+ *	eof=^D		eol=\0          status=^T
  */
-#define INIT_C_CC "\003\034\177\025\1\0\0\0\021\023\032\0\022\017\027\026\004\0"
+#define INIT_C_CC "\003\034\177\025\1\0\0\0\021\023\032\0\022\017\027\026\004\0\024"
 
 #include <linux/string.h>
 
diff --git a/arch/mips/include/uapi/asm/ioctls.h b/arch/mips/include/uapi/asm/ioctls.h
index 16aa8a766aec..f9ec28ac38db 100644
--- a/arch/mips/include/uapi/asm/ioctls.h
+++ b/arch/mips/include/uapi/asm/ioctls.h
@@ -115,5 +115,6 @@
 #define TIOCSERSETMULTI 0x5490 /* Set multiport config */
 #define TIOCMIWAIT	0x5491 /* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x5492 /* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x93) /* display process group stats on tty */
 
 #endif /* __ASM_IOCTLS_H */
diff --git a/arch/mips/include/uapi/asm/termbits.h b/arch/mips/include/uapi/asm/termbits.h
index dfeffba729b7..a10be13a6f7b 100644
--- a/arch/mips/include/uapi/asm/termbits.h
+++ b/arch/mips/include/uapi/asm/termbits.h
@@ -78,6 +78,7 @@ struct ktermios {
 #define VLNEXT		15		/* Literal-next character [IEXTEN].  */
 #define VEOF		16		/* End-of-file character [ICANON].  */
 #define VEOL		17		/* End-of-line character [ICANON].  */
+#define VSTATUS         18
 
 /* c_iflag bits */
 #define IGNBRK	0000001		/* Ignore break condition.  */
@@ -205,6 +206,7 @@ struct ktermios {
 #define TOSTOP	0100000		/* Send SIGTTOU for background output.	*/
 #define ITOSTOP TOSTOP
 #define EXTPROC 0200000		/* External processing on pty */
+#define NOKERNINFO 0400000	/* Disable kernel status message */
 
 /* ioctl (fd, TIOCSERGETLSR, &result) where result may be as below */
 #define TIOCSER_TEMT	0x01	/* Transmitter physically empty */
diff --git a/arch/parisc/include/asm/termios.h b/arch/parisc/include/asm/termios.h
index cded9dc90c1b..63c6c7edb0ff 100644
--- a/arch/parisc/include/asm/termios.h
+++ b/arch/parisc/include/asm/termios.h
@@ -9,9 +9,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/parisc/include/uapi/asm/ioctls.h b/arch/parisc/include/uapi/asm/ioctls.h
index 82d1148c6379..1ac156dd8209 100644
--- a/arch/parisc/include/uapi/asm/ioctls.h
+++ b/arch/parisc/include/uapi/asm/ioctls.h
@@ -80,6 +80,7 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 #define FIOQSIZE	0x5460	/* Get exact space used by quota */
 
 #define TIOCSTART	0x5461
diff --git a/arch/parisc/include/uapi/asm/termbits.h b/arch/parisc/include/uapi/asm/termbits.h
index 40e920f8d683..b449d8ea1c00 100644
--- a/arch/parisc/include/uapi/asm/termbits.h
+++ b/arch/parisc/include/uapi/asm/termbits.h
@@ -58,6 +58,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 
 /* c_iflag bits */
@@ -182,6 +183,7 @@ struct ktermios {
 #define PENDIN  0040000
 #define IEXTEN  0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
diff --git a/arch/powerpc/include/asm/termios.h b/arch/powerpc/include/asm/termios.h
index 205de8f8a9d3..e5381c8f86f0 100644
--- a/arch/powerpc/include/asm/termios.h
+++ b/arch/powerpc/include/asm/termios.h
@@ -10,8 +10,8 @@
 
 #include <uapi/asm/termios.h>
 
-/*                   ^C  ^\ del  ^U  ^D   1   0   0   0   0  ^W  ^R  ^Z  ^Q  ^S  ^V  ^U  */
-#define INIT_C_CC "\003\034\177\025\004\001\000\000\000\000\027\022\032\021\023\026\025" 
+/*                   ^C  ^\ del  ^U  ^D   1   0   0   0   0  ^W  ^R  ^Z  ^Q  ^S  ^V  ^U  ^T */
+#define INIT_C_CC "\003\034\177\025\004\001\000\000\000\000\027\022\032\021\023\026\025\024"
 
 #include <asm-generic/termios-base.h>
 
diff --git a/arch/powerpc/include/uapi/asm/ioctls.h b/arch/powerpc/include/uapi/asm/ioctls.h
index 2c145da3b774..0a0755863500 100644
--- a/arch/powerpc/include/uapi/asm/ioctls.h
+++ b/arch/powerpc/include/uapi/asm/ioctls.h
@@ -120,4 +120,6 @@
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
 
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
+
 #endif	/* _ASM_POWERPC_IOCTLS_H */
diff --git a/arch/powerpc/include/uapi/asm/termbits.h b/arch/powerpc/include/uapi/asm/termbits.h
index ed18bc61f63d..50d787d95c91 100644
--- a/arch/powerpc/include/uapi/asm/termbits.h
+++ b/arch/powerpc/include/uapi/asm/termbits.h
@@ -62,6 +62,7 @@ struct ktermios {
 #define VSTOP		14
 #define VLNEXT		15
 #define VDISCARD	16
+#define VSTATUS		17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -191,6 +192,7 @@ struct ktermios {
 #define PENDIN	0x20000000
 #define IEXTEN	0x00000400
 #define EXTPROC	0x10000000
+#define NOKERNINFO 0x40000000
 
 /* Values for the ACTION argument to `tcflow'.  */
 #define	TCOOFF		0
diff --git a/arch/s390/include/asm/termios.h b/arch/s390/include/asm/termios.h
index 46fa3020b41e..8d2017f4905d 100644
--- a/arch/s390/include/asm/termios.h
+++ b/arch/s390/include/asm/termios.h
@@ -14,9 +14,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         vstatus=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 #define user_termios_to_kernel_termios(k, u) copy_from_user(k, u, sizeof(struct termios2))
 #define kernel_termios_to_user_termios(u, k) copy_to_user(u, k, sizeof(struct termios2))
diff --git a/arch/sh/include/uapi/asm/ioctls.h b/arch/sh/include/uapi/asm/ioctls.h
index 11866d4f60e1..fefef10922ec 100644
--- a/arch/sh/include/uapi/asm/ioctls.h
+++ b/arch/sh/include/uapi/asm/ioctls.h
@@ -112,5 +112,6 @@
 
 #define TIOCMIWAIT	_IO('T', 92) /* 0x545C */	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5F)	/* display process group stats on tty */
 
 #endif /* __ASM_SH_IOCTLS_H */
diff --git a/arch/sparc/include/uapi/asm/ioctls.h b/arch/sparc/include/uapi/asm/ioctls.h
index 7fd2f5873c9e..9819090bd850 100644
--- a/arch/sparc/include/uapi/asm/ioctls.h
+++ b/arch/sparc/include/uapi/asm/ioctls.h
@@ -124,6 +124,7 @@
 #define TIOCSERSETMULTI 0x545B /* Set multiport config */
 #define TIOCMIWAIT	0x545C /* Wait for change on serial input line(s) */
 #define TIOCGICOUNT	0x545D /* Read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E) /* Display process group stats on tty */
 
 /* Kernel definitions */
 
diff --git a/arch/sparc/include/uapi/asm/termbits.h b/arch/sparc/include/uapi/asm/termbits.h
index ce5ad5d0f105..b8441ce42278 100644
--- a/arch/sparc/include/uapi/asm/termbits.h
+++ b/arch/sparc/include/uapi/asm/termbits.h
@@ -80,6 +80,7 @@ struct ktermios {
 #define VDISCARD 13
 #define VWERASE  14
 #define VLNEXT   15
+#define VSTATUS  16
 
 /* Kernel keeps vmin/vtime separated, user apps assume vmin/vtime is
  * shared with eof/eol
@@ -224,6 +225,7 @@ struct ktermios {
 #define PENDIN	0x00004000
 #define IEXTEN	0x00008000
 #define EXTPROC	0x00010000
+#define NOKERNINFO 0x00020000
 
 /* modem lines */
 #define TIOCM_LE	0x001
diff --git a/arch/xtensa/include/uapi/asm/ioctls.h b/arch/xtensa/include/uapi/asm/ioctls.h
index 6d4a87296c95..f92fb8e5b2a5 100644
--- a/arch/xtensa/include/uapi/asm/ioctls.h
+++ b/arch/xtensa/include/uapi/asm/ioctls.h
@@ -126,5 +126,6 @@
 
 #define TIOCMIWAIT	_IO('T', 92) /* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 
 #endif /* _XTENSA_IOCTLS_H */
diff --git a/include/asm-generic/termios.h b/include/asm-generic/termios.h
index b1398d0d4a1d..9b080e1a82d4 100644
--- a/include/asm-generic/termios.h
+++ b/include/asm-generic/termios.h
@@ -10,9 +10,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/include/uapi/asm-generic/ioctls.h b/include/uapi/asm-generic/ioctls.h
index cdc9f4ca8c27..02ceb990ce9b 100644
--- a/include/uapi/asm-generic/ioctls.h
+++ b/include/uapi/asm-generic/ioctls.h
@@ -97,6 +97,7 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT        _IO('T', 0x5E)	/* display process group stats on tty */
 
 /*
  * Some arches already define FIOQSIZE due to a historical
diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
index 2fbaf9ae89dd..6219803d6f4d 100644
--- a/include/uapi/asm-generic/termbits.h
+++ b/include/uapi/asm-generic/termbits.h
@@ -58,6 +58,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -180,6 +181,7 @@ struct ktermios {
 #define PENDIN	0040000
 #define IEXTEN	0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
-- 
2.30.2

[PATCH v2 2/3] status: Add user space API definitions for VSTATUS, NOKERNINFO and TIOCSTAT

[Walt Drummond]

Add definitions for the VSTATUS control character, and the NOKERNINFO
local control flag in the termios struct, and add an ioctl number for
the ioctl TIOCSTAT.  Also add a default VSTATUS character (Ctrl-T)
default valuses in termios.c_cc.  Do this for all architectures.

Signed-off-by: Walt Drummond <walt@drummond.us>
---
 arch/alpha/include/asm/termios.h         | 4 ++--
 arch/alpha/include/uapi/asm/ioctls.h     | 1 +
 arch/alpha/include/uapi/asm/termbits.h   | 2 ++
 arch/ia64/include/asm/termios.h          | 4 ++--
 arch/ia64/include/uapi/asm/termbits.h    | 2 ++
 arch/mips/include/asm/termios.h          | 4 ++--
 arch/mips/include/uapi/asm/ioctls.h      | 1 +
 arch/mips/include/uapi/asm/termbits.h    | 2 ++
 arch/parisc/include/asm/termios.h        | 4 ++--
 arch/parisc/include/uapi/asm/ioctls.h    | 1 +
 arch/parisc/include/uapi/asm/termbits.h  | 2 ++
 arch/powerpc/include/asm/termios.h       | 4 ++--
 arch/powerpc/include/uapi/asm/ioctls.h   | 2 ++
 arch/powerpc/include/uapi/asm/termbits.h | 2 ++
 arch/s390/include/asm/termios.h          | 4 ++--
 arch/sh/include/uapi/asm/ioctls.h        | 1 +
 arch/sparc/include/uapi/asm/ioctls.h     | 1 +
 arch/sparc/include/uapi/asm/termbits.h   | 2 ++
 arch/xtensa/include/uapi/asm/ioctls.h    | 1 +
 include/asm-generic/termios.h            | 4 ++--
 include/uapi/asm-generic/ioctls.h        | 1 +
 include/uapi/asm-generic/termbits.h      | 2 ++
 22 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
index b7c77bb1bfd2..d28ddc649286 100644
--- a/arch/alpha/include/asm/termios.h
+++ b/arch/alpha/include/asm/termios.h
@@ -8,9 +8,9 @@
 	werase=^W	kill=^U		reprint=^R	sxtc=\0
 	intr=^C		quit=^\		susp=^Z		<OSF/1 VDSUSP>
 	start=^Q	stop=^S		lnext=^V	discard=^U
-	vmin=\1		vtime=\0
+	vmin=\1		vtime=\0        status=^T
 */
-#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000"
+#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
index 971311605288..70fdeab2b5f2 100644
--- a/arch/alpha/include/uapi/asm/ioctls.h
+++ b/arch/alpha/include/uapi/asm/ioctls.h
@@ -124,5 +124,6 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 
 #endif /* _ASM_ALPHA_IOCTLS_H */
diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
index 4575ba34a0ea..9a1b9aa92d29 100644
--- a/arch/alpha/include/uapi/asm/termbits.h
+++ b/arch/alpha/include/uapi/asm/termbits.h
@@ -70,6 +70,7 @@ struct ktermios {
 #define VDISCARD 15
 #define VMIN 16
 #define VTIME 17
+#define VSTATUS 18
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -203,6 +204,7 @@ struct ktermios {
 #define PENDIN	0x20000000
 #define IEXTEN	0x00000400
 #define EXTPROC	0x10000000
+#define NOKERNINFO 0x40000000
 
 /* Values for the ACTION argument to `tcflow'.  */
 #define	TCOOFF		0
diff --git a/arch/ia64/include/asm/termios.h b/arch/ia64/include/asm/termios.h
index 589c026444cc..40e83f9b6ead 100644
--- a/arch/ia64/include/asm/termios.h
+++ b/arch/ia64/include/asm/termios.h
@@ -15,9 +15,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/ia64/include/uapi/asm/termbits.h b/arch/ia64/include/uapi/asm/termbits.h
index 000a1a297c75..0b5fea00343b 100644
--- a/arch/ia64/include/uapi/asm/termbits.h
+++ b/arch/ia64/include/uapi/asm/termbits.h
@@ -67,6 +67,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -189,6 +190,7 @@ struct ktermios {
 #define PENDIN	0040000
 #define IEXTEN	0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
diff --git a/arch/mips/include/asm/termios.h b/arch/mips/include/asm/termios.h
index bc29eeacc55a..04729018d882 100644
--- a/arch/mips/include/asm/termios.h
+++ b/arch/mips/include/asm/termios.h
@@ -17,9 +17,9 @@
  *	vmin=\1		vtime=\0	eol2=\0		swtc=\0
  *	start=^Q	stop=^S		susp=^Z		vdsusp  *	reprint=^R	discard=^U	werase=^W	lnext=^V
- *	eof=^D		eol=\0
+ *	eof=^D		eol=\0          status=^T
  */
-#define INIT_C_CC "\003\034\177\025\1\0\0\0\021\023\032\0\022\017\027\026\004\0"
+#define INIT_C_CC "\003\034\177\025\1\0\0\0\021\023\032\0\022\017\027\026\004\0\024"
 
 #include <linux/string.h>
 
diff --git a/arch/mips/include/uapi/asm/ioctls.h b/arch/mips/include/uapi/asm/ioctls.h
index 16aa8a766aec..f9ec28ac38db 100644
--- a/arch/mips/include/uapi/asm/ioctls.h
+++ b/arch/mips/include/uapi/asm/ioctls.h
@@ -115,5 +115,6 @@
 #define TIOCSERSETMULTI 0x5490 /* Set multiport config */
 #define TIOCMIWAIT	0x5491 /* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x5492 /* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x93) /* display process group stats on tty */
 
 #endif /* __ASM_IOCTLS_H */
diff --git a/arch/mips/include/uapi/asm/termbits.h b/arch/mips/include/uapi/asm/termbits.h
index dfeffba729b7..a10be13a6f7b 100644
--- a/arch/mips/include/uapi/asm/termbits.h
+++ b/arch/mips/include/uapi/asm/termbits.h
@@ -78,6 +78,7 @@ struct ktermios {
 #define VLNEXT		15		/* Literal-next character [IEXTEN].  */
 #define VEOF		16		/* End-of-file character [ICANON].  */
 #define VEOL		17		/* End-of-line character [ICANON].  */
+#define VSTATUS         18
 
 /* c_iflag bits */
 #define IGNBRK	0000001		/* Ignore break condition.  */
@@ -205,6 +206,7 @@ struct ktermios {
 #define TOSTOP	0100000		/* Send SIGTTOU for background output.	*/
 #define ITOSTOP TOSTOP
 #define EXTPROC 0200000		/* External processing on pty */
+#define NOKERNINFO 0400000	/* Disable kernel status message */
 
 /* ioctl (fd, TIOCSERGETLSR, &result) where result may be as below */
 #define TIOCSER_TEMT	0x01	/* Transmitter physically empty */
diff --git a/arch/parisc/include/asm/termios.h b/arch/parisc/include/asm/termios.h
index cded9dc90c1b..63c6c7edb0ff 100644
--- a/arch/parisc/include/asm/termios.h
+++ b/arch/parisc/include/asm/termios.h
@@ -9,9 +9,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/arch/parisc/include/uapi/asm/ioctls.h b/arch/parisc/include/uapi/asm/ioctls.h
index 82d1148c6379..1ac156dd8209 100644
--- a/arch/parisc/include/uapi/asm/ioctls.h
+++ b/arch/parisc/include/uapi/asm/ioctls.h
@@ -80,6 +80,7 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 #define FIOQSIZE	0x5460	/* Get exact space used by quota */
 
 #define TIOCSTART	0x5461
diff --git a/arch/parisc/include/uapi/asm/termbits.h b/arch/parisc/include/uapi/asm/termbits.h
index 40e920f8d683..b449d8ea1c00 100644
--- a/arch/parisc/include/uapi/asm/termbits.h
+++ b/arch/parisc/include/uapi/asm/termbits.h
@@ -58,6 +58,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 
 /* c_iflag bits */
@@ -182,6 +183,7 @@ struct ktermios {
 #define PENDIN  0040000
 #define IEXTEN  0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
diff --git a/arch/powerpc/include/asm/termios.h b/arch/powerpc/include/asm/termios.h
index 205de8f8a9d3..e5381c8f86f0 100644
--- a/arch/powerpc/include/asm/termios.h
+++ b/arch/powerpc/include/asm/termios.h
@@ -10,8 +10,8 @@
 
 #include <uapi/asm/termios.h>
 
-/*                   ^C  ^\ del  ^U  ^D   1   0   0   0   0  ^W  ^R  ^Z  ^Q  ^S  ^V  ^U  */
-#define INIT_C_CC "\003\034\177\025\004\001\000\000\000\000\027\022\032\021\023\026\025" 
+/*                   ^C  ^\ del  ^U  ^D   1   0   0   0   0  ^W  ^R  ^Z  ^Q  ^S  ^V  ^U  ^T */
+#define INIT_C_CC "\003\034\177\025\004\001\000\000\000\000\027\022\032\021\023\026\025\024"
 
 #include <asm-generic/termios-base.h>
 
diff --git a/arch/powerpc/include/uapi/asm/ioctls.h b/arch/powerpc/include/uapi/asm/ioctls.h
index 2c145da3b774..0a0755863500 100644
--- a/arch/powerpc/include/uapi/asm/ioctls.h
+++ b/arch/powerpc/include/uapi/asm/ioctls.h
@@ -120,4 +120,6 @@
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
 
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
+
 #endif	/* _ASM_POWERPC_IOCTLS_H */
diff --git a/arch/powerpc/include/uapi/asm/termbits.h b/arch/powerpc/include/uapi/asm/termbits.h
index ed18bc61f63d..50d787d95c91 100644
--- a/arch/powerpc/include/uapi/asm/termbits.h
+++ b/arch/powerpc/include/uapi/asm/termbits.h
@@ -62,6 +62,7 @@ struct ktermios {
 #define VSTOP		14
 #define VLNEXT		15
 #define VDISCARD	16
+#define VSTATUS		17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -191,6 +192,7 @@ struct ktermios {
 #define PENDIN	0x20000000
 #define IEXTEN	0x00000400
 #define EXTPROC	0x10000000
+#define NOKERNINFO 0x40000000
 
 /* Values for the ACTION argument to `tcflow'.  */
 #define	TCOOFF		0
diff --git a/arch/s390/include/asm/termios.h b/arch/s390/include/asm/termios.h
index 46fa3020b41e..8d2017f4905d 100644
--- a/arch/s390/include/asm/termios.h
+++ b/arch/s390/include/asm/termios.h
@@ -14,9 +14,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         vstatus=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 #define user_termios_to_kernel_termios(k, u) copy_from_user(k, u, sizeof(struct termios2))
 #define kernel_termios_to_user_termios(u, k) copy_to_user(u, k, sizeof(struct termios2))
diff --git a/arch/sh/include/uapi/asm/ioctls.h b/arch/sh/include/uapi/asm/ioctls.h
index 11866d4f60e1..fefef10922ec 100644
--- a/arch/sh/include/uapi/asm/ioctls.h
+++ b/arch/sh/include/uapi/asm/ioctls.h
@@ -112,5 +112,6 @@
 
 #define TIOCMIWAIT	_IO('T', 92) /* 0x545C */	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5F)	/* display process group stats on tty */
 
 #endif /* __ASM_SH_IOCTLS_H */
diff --git a/arch/sparc/include/uapi/asm/ioctls.h b/arch/sparc/include/uapi/asm/ioctls.h
index 7fd2f5873c9e..9819090bd850 100644
--- a/arch/sparc/include/uapi/asm/ioctls.h
+++ b/arch/sparc/include/uapi/asm/ioctls.h
@@ -124,6 +124,7 @@
 #define TIOCSERSETMULTI 0x545B /* Set multiport config */
 #define TIOCMIWAIT	0x545C /* Wait for change on serial input line(s) */
 #define TIOCGICOUNT	0x545D /* Read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E) /* Display process group stats on tty */
 
 /* Kernel definitions */
 
diff --git a/arch/sparc/include/uapi/asm/termbits.h b/arch/sparc/include/uapi/asm/termbits.h
index ce5ad5d0f105..b8441ce42278 100644
--- a/arch/sparc/include/uapi/asm/termbits.h
+++ b/arch/sparc/include/uapi/asm/termbits.h
@@ -80,6 +80,7 @@ struct ktermios {
 #define VDISCARD 13
 #define VWERASE  14
 #define VLNEXT   15
+#define VSTATUS  16
 
 /* Kernel keeps vmin/vtime separated, user apps assume vmin/vtime is
  * shared with eof/eol
@@ -224,6 +225,7 @@ struct ktermios {
 #define PENDIN	0x00004000
 #define IEXTEN	0x00008000
 #define EXTPROC	0x00010000
+#define NOKERNINFO 0x00020000
 
 /* modem lines */
 #define TIOCM_LE	0x001
diff --git a/arch/xtensa/include/uapi/asm/ioctls.h b/arch/xtensa/include/uapi/asm/ioctls.h
index 6d4a87296c95..f92fb8e5b2a5 100644
--- a/arch/xtensa/include/uapi/asm/ioctls.h
+++ b/arch/xtensa/include/uapi/asm/ioctls.h
@@ -126,5 +126,6 @@
 
 #define TIOCMIWAIT	_IO('T', 92) /* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
 
 #endif /* _XTENSA_IOCTLS_H */
diff --git a/include/asm-generic/termios.h b/include/asm-generic/termios.h
index b1398d0d4a1d..9b080e1a82d4 100644
--- a/include/asm-generic/termios.h
+++ b/include/asm-generic/termios.h
@@ -10,9 +10,9 @@
 	eof=^D		vtime=\0	vmin=\1		sxtc=\0
 	start=^Q	stop=^S		susp=^Z		eol=\0
 	reprint=^R	discard=^U	werase=^W	lnext=^V
-	eol2=\0
+	eol2=\0         status=^T
 */
-#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
+#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
 
 /*
  * Translate a "termio" structure into a "termios". Ugh.
diff --git a/include/uapi/asm-generic/ioctls.h b/include/uapi/asm-generic/ioctls.h
index cdc9f4ca8c27..02ceb990ce9b 100644
--- a/include/uapi/asm-generic/ioctls.h
+++ b/include/uapi/asm-generic/ioctls.h
@@ -97,6 +97,7 @@
 
 #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
+#define TIOCSTAT        _IO('T', 0x5E)	/* display process group stats on tty */
 
 /*
  * Some arches already define FIOQSIZE due to a historical
diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
index 2fbaf9ae89dd..6219803d6f4d 100644
--- a/include/uapi/asm-generic/termbits.h
+++ b/include/uapi/asm-generic/termbits.h
@@ -58,6 +58,7 @@ struct ktermios {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VSTATUS 17
 
 /* c_iflag bits */
 #define IGNBRK	0000001
@@ -180,6 +181,7 @@ struct ktermios {
 #define PENDIN	0040000
 #define IEXTEN	0100000
 #define EXTPROC	0200000
+#define NOKERNINFO 0400000
 
 /* tcflow() and TCXONC use these */
 #define	TCOOFF		0
-- 
2.30.2

[PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Walt Drummond]

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 <walt@drummond.us>
---
 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 000000000000..f0e053651368
--- /dev/null
+++ b/drivers/tty/n_tty_status.c
@@ -0,0 +1,181 @@
+// 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>
+#include <linux/sched/mm.h>
+
+/* Convert nanoseconds into centiseconds */
+static inline long ns_to_cs(long l)
+{
+	return l / (NSEC_PER_MSEC * 10);
+
+}
+
+/* We want the pid from the context of session */
+static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
+{
+	struct pid_namespace *ns;
+
+	spin_lock_irq(&tty->ctrl.lock);
+	ns = ns_of_pid(tty->ctrl.session);
+	spin_unlock_irq(&tty->ctrl.lock);
+
+	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
+}
+
+/* This is the same odd "bitmap" described in
+ * fs/proc/array.c:get_task_state().  Consistency with standard
+ * implementations of VSTATUS requires a different set of state
+ * names.
+ */
+static const char * const task_state_name_array[] = {
+	"running",
+	"sleeping",
+	"disk sleep",
+	"stopped",
+	"tracing stop",
+	"dead",
+	"zombie",
+	"parked",
+	"idle",
+};
+
+static inline const char *get_task_state_name(struct task_struct *tsk)
+{
+	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));
+	return task_state_name_array[task_state_index(tsk)];
+}
+
+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 tty_struct *tty)
+{
+	struct task_struct *new, *winner = NULL;
+
+	read_lock(&tasklist_lock);
+	spin_lock_irq(&tty->ctrl.lock);
+
+	do_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new) {
+		winner = compare(new, winner);
+	} while_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new);
+
+	spin_unlock_irq(&tty->ctrl.lock);
+
+	if (winner)
+		winner = get_task_struct(winner);
+
+	read_unlock(&tasklist_lock);
+
+	return winner;
+}
+
+size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
+{
+	struct task_struct *p;
+	struct mm_struct *mm;
+	struct rusage rusage;
+	unsigned long loadavg[3];
+	uint64_t pcpu, cputime, wallclock;
+	struct timespec64 utime, stime, rtime;
+	char tname[TASK_COMM_LEN];
+	unsigned int pid;
+	char *state;
+	unsigned long rss = 0;
+	size_t len = 0;
+
+	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;
+	}
+
+	/* Note that if p is refcounted */
+	p = pick_process(tty);
+	if (p == NULL) {
+		len += scnprintf(msg + len, msglen - len,
+				 "empty foreground process group\n");
+		goto out;
+	}
+
+	mm = get_task_mm(p);
+	if (mm) {
+		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
+		mmput(mm);
+	}
+	get_task_comm(tname, p);
+	getrusage(p, RUSAGE_BOTH, &rusage);
+	pid = __get_pid(p, tty);
+	state = (char *) get_task_state_name(p);
+	wallclock = ktime_get_ns() - p->start_time;
+	put_task_struct(p);
+
+	/* After this point, any of the information we have on p might
+	 * become stale.  It's OK if the status message is a little bit
+	 * lossy.
+	 */
+
+	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,	pid, state,
+			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
+			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
+			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
+			 pcpu, rss);
+
+out:
+	return len;
+}
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 cbe5d535a69d..2e483708608c 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -49,6 +49,7 @@
 #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))
@@ -114,6 +115,7 @@
 #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;
@@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
 static inline void n_tty_init(void) { }
 #endif
 
+/* n_tty_status.c */
+size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);
+
 /* tty_audit.c */
 #ifdef CONFIG_AUDIT
 extern void tty_audit_exit(void);
-- 
2.30.2

[PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Walt Drummond]

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 <walt@drummond.us>
---
 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 000000000000..f0e053651368
--- /dev/null
+++ b/drivers/tty/n_tty_status.c
@@ -0,0 +1,181 @@
+// 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>
+#include <linux/sched/mm.h>
+
+/* Convert nanoseconds into centiseconds */
+static inline long ns_to_cs(long l)
+{
+	return l / (NSEC_PER_MSEC * 10);
+
+}
+
+/* We want the pid from the context of session */
+static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
+{
+	struct pid_namespace *ns;
+
+	spin_lock_irq(&tty->ctrl.lock);
+	ns = ns_of_pid(tty->ctrl.session);
+	spin_unlock_irq(&tty->ctrl.lock);
+
+	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
+}
+
+/* This is the same odd "bitmap" described in
+ * fs/proc/array.c:get_task_state().  Consistency with standard
+ * implementations of VSTATUS requires a different set of state
+ * names.
+ */
+static const char * const task_state_name_array[] = {
+	"running",
+	"sleeping",
+	"disk sleep",
+	"stopped",
+	"tracing stop",
+	"dead",
+	"zombie",
+	"parked",
+	"idle",
+};
+
+static inline const char *get_task_state_name(struct task_struct *tsk)
+{
+	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));
+	return task_state_name_array[task_state_index(tsk)];
+}
+
+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 tty_struct *tty)
+{
+	struct task_struct *new, *winner = NULL;
+
+	read_lock(&tasklist_lock);
+	spin_lock_irq(&tty->ctrl.lock);
+
+	do_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new) {
+		winner = compare(new, winner);
+	} while_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new);
+
+	spin_unlock_irq(&tty->ctrl.lock);
+
+	if (winner)
+		winner = get_task_struct(winner);
+
+	read_unlock(&tasklist_lock);
+
+	return winner;
+}
+
+size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
+{
+	struct task_struct *p;
+	struct mm_struct *mm;
+	struct rusage rusage;
+	unsigned long loadavg[3];
+	uint64_t pcpu, cputime, wallclock;
+	struct timespec64 utime, stime, rtime;
+	char tname[TASK_COMM_LEN];
+	unsigned int pid;
+	char *state;
+	unsigned long rss = 0;
+	size_t len = 0;
+
+	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;
+	}
+
+	/* Note that if p is refcounted */
+	p = pick_process(tty);
+	if (p == NULL) {
+		len += scnprintf(msg + len, msglen - len,
+				 "empty foreground process group\n");
+		goto out;
+	}
+
+	mm = get_task_mm(p);
+	if (mm) {
+		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
+		mmput(mm);
+	}
+	get_task_comm(tname, p);
+	getrusage(p, RUSAGE_BOTH, &rusage);
+	pid = __get_pid(p, tty);
+	state = (char *) get_task_state_name(p);
+	wallclock = ktime_get_ns() - p->start_time;
+	put_task_struct(p);
+
+	/* After this point, any of the information we have on p might
+	 * become stale.  It's OK if the status message is a little bit
+	 * lossy.
+	 */
+
+	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,	pid, state,
+			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
+			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
+			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
+			 pcpu, rss);
+
+out:
+	return len;
+}
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 cbe5d535a69d..2e483708608c 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -49,6 +49,7 @@
 #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))
@@ -114,6 +115,7 @@
 #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;
@@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
 static inline void n_tty_init(void) { }
 #endif
 
+/* n_tty_status.c */
+size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);
+
 /* tty_audit.c */
 #ifdef CONFIG_AUDIT
 extern void tty_audit_exit(void);
-- 
2.30.2

[PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TI

[Walt Drummond]

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 <walt@drummond.us>
---
 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 000000000000..f0e053651368
--- /dev/null
+++ b/drivers/tty/n_tty_status.c
@@ -0,0 +1,181 @@
+// 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>
+#include <linux/sched/mm.h>
+
+/* Convert nanoseconds into centiseconds */
+static inline long ns_to_cs(long l)
+{
+	return l / (NSEC_PER_MSEC * 10);
+
+}
+
+/* We want the pid from the context of session */
+static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
+{
+	struct pid_namespace *ns;
+
+	spin_lock_irq(&tty->ctrl.lock);
+	ns = ns_of_pid(tty->ctrl.session);
+	spin_unlock_irq(&tty->ctrl.lock);
+
+	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
+}
+
+/* This is the same odd "bitmap" described in
+ * fs/proc/array.c:get_task_state().  Consistency with standard
+ * implementations of VSTATUS requires a different set of state
+ * names.
+ */
+static const char * const task_state_name_array[] = {
+	"running",
+	"sleeping",
+	"disk sleep",
+	"stopped",
+	"tracing stop",
+	"dead",
+	"zombie",
+	"parked",
+	"idle",
+};
+
+static inline const char *get_task_state_name(struct task_struct *tsk)
+{
+	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));
+	return task_state_name_array[task_state_index(tsk)];
+}
+
+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 tty_struct *tty)
+{
+	struct task_struct *new, *winner = NULL;
+
+	read_lock(&tasklist_lock);
+	spin_lock_irq(&tty->ctrl.lock);
+
+	do_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new) {
+		winner = compare(new, winner);
+	} while_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new);
+
+	spin_unlock_irq(&tty->ctrl.lock);
+
+	if (winner)
+		winner = get_task_struct(winner);
+
+	read_unlock(&tasklist_lock);
+
+	return winner;
+}
+
+size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
+{
+	struct task_struct *p;
+	struct mm_struct *mm;
+	struct rusage rusage;
+	unsigned long loadavg[3];
+	uint64_t pcpu, cputime, wallclock;
+	struct timespec64 utime, stime, rtime;
+	char tname[TASK_COMM_LEN];
+	unsigned int pid;
+	char *state;
+	unsigned long rss = 0;
+	size_t len = 0;
+
+	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;
+	}
+
+	/* Note that if p is refcounted */
+	p = pick_process(tty);
+	if (p = NULL) {
+		len += scnprintf(msg + len, msglen - len,
+				 "empty foreground process group\n");
+		goto out;
+	}
+
+	mm = get_task_mm(p);
+	if (mm) {
+		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
+		mmput(mm);
+	}
+	get_task_comm(tname, p);
+	getrusage(p, RUSAGE_BOTH, &rusage);
+	pid = __get_pid(p, tty);
+	state = (char *) get_task_state_name(p);
+	wallclock = ktime_get_ns() - p->start_time;
+	put_task_struct(p);
+
+	/* After this point, any of the information we have on p might
+	 * become stale.  It's OK if the status message is a little bit
+	 * lossy.
+	 */
+
+	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,	pid, state,
+			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
+			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
+			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
+			 pcpu, rss);
+
+out:
+	return len;
+}
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 cbe5d535a69d..2e483708608c 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -49,6 +49,7 @@
 #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))
@@ -114,6 +115,7 @@
 #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;
@@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
 static inline void n_tty_init(void) { }
 #endif
 
+/* n_tty_status.c */
+size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);
+
 /* tty_audit.c */
 #ifdef CONFIG_AUDIT
 extern void tty_audit_exit(void);
-- 
2.30.2

Re: [PATCH v2 2/3] status: Add user space API definitions for VSTATUS, NOKERNINFO and TIOCSTAT

[Greg KH]

On Sun, Feb 06, 2022 at 07:48:53AM -0800, Walt Drummond wrote:
> Add definitions for the VSTATUS control character, and the NOKERNINFO
> local control flag in the termios struct, and add an ioctl number for
> the ioctl TIOCSTAT.  Also add a default VSTATUS character (Ctrl-T)
> default valuses in termios.c_cc.  Do this for all architectures.
> 
> Signed-off-by: Walt Drummond <walt@drummond.us>
> ---
>  arch/alpha/include/asm/termios.h         | 4 ++--
>  arch/alpha/include/uapi/asm/ioctls.h     | 1 +
>  arch/alpha/include/uapi/asm/termbits.h   | 2 ++
>  arch/ia64/include/asm/termios.h          | 4 ++--
>  arch/ia64/include/uapi/asm/termbits.h    | 2 ++
>  arch/mips/include/asm/termios.h          | 4 ++--
>  arch/mips/include/uapi/asm/ioctls.h      | 1 +
>  arch/mips/include/uapi/asm/termbits.h    | 2 ++
>  arch/parisc/include/asm/termios.h        | 4 ++--
>  arch/parisc/include/uapi/asm/ioctls.h    | 1 +
>  arch/parisc/include/uapi/asm/termbits.h  | 2 ++
>  arch/powerpc/include/asm/termios.h       | 4 ++--
>  arch/powerpc/include/uapi/asm/ioctls.h   | 2 ++
>  arch/powerpc/include/uapi/asm/termbits.h | 2 ++
>  arch/s390/include/asm/termios.h          | 4 ++--
>  arch/sh/include/uapi/asm/ioctls.h        | 1 +
>  arch/sparc/include/uapi/asm/ioctls.h     | 1 +
>  arch/sparc/include/uapi/asm/termbits.h   | 2 ++
>  arch/xtensa/include/uapi/asm/ioctls.h    | 1 +
>  include/asm-generic/termios.h            | 4 ++--
>  include/uapi/asm-generic/ioctls.h        | 1 +
>  include/uapi/asm-generic/termbits.h      | 2 ++
>  22 files changed, 37 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
> index b7c77bb1bfd2..d28ddc649286 100644
> --- a/arch/alpha/include/asm/termios.h
> +++ b/arch/alpha/include/asm/termios.h
> @@ -8,9 +8,9 @@
>  	werase=^W	kill=^U		reprint=^R	sxtc=\0
>  	intr=^C		quit=^\		susp=^Z		<OSF/1 VDSUSP>
>  	start=^Q	stop=^S		lnext=^V	discard=^U
> -	vmin=\1		vtime=\0
> +	vmin=\1		vtime=\0        status=^T
>  */
> -#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000"
> +#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000\024"
>  
>  /*
>   * Translate a "termio" structure into a "termios". Ugh.
> diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
> index 971311605288..70fdeab2b5f2 100644
> --- a/arch/alpha/include/uapi/asm/ioctls.h
> +++ b/arch/alpha/include/uapi/asm/ioctls.h
> @@ -124,5 +124,6 @@
>  
>  #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
> +#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
>  
>  #endif /* _ASM_ALPHA_IOCTLS_H */
> diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
> index 4575ba34a0ea..9a1b9aa92d29 100644
> --- a/arch/alpha/include/uapi/asm/termbits.h
> +++ b/arch/alpha/include/uapi/asm/termbits.h
> @@ -70,6 +70,7 @@ struct ktermios {
>  #define VDISCARD 15
>  #define VMIN 16
>  #define VTIME 17
> +#define VSTATUS 18
>  
>  /* c_iflag bits */
>  #define IGNBRK	0000001
> @@ -203,6 +204,7 @@ struct ktermios {
>  #define PENDIN	0x20000000
>  #define IEXTEN	0x00000400
>  #define EXTPROC	0x10000000
> +#define NOKERNINFO 0x40000000

Here, and elsewhere, you seem to mix tabs and spaces.  Please use what
is in the original file (tabs here.)

>  /* Values for the ACTION argument to `tcflow'.  */
>  #define	TCOOFF		0
> diff --git a/arch/ia64/include/asm/termios.h b/arch/ia64/include/asm/termios.h
> index 589c026444cc..40e83f9b6ead 100644
> --- a/arch/ia64/include/asm/termios.h
> +++ b/arch/ia64/include/asm/termios.h
> @@ -15,9 +15,9 @@
>  	eof=^D		vtime=\0	vmin=\1		sxtc=\0
>  	start=^Q	stop=^S		susp=^Z		eol=\0
>  	reprint=^R	discard=^U	werase=^W	lnext=^V
> -	eol2=\0
> +	eol2=\0         status=^T

Same here.  And for the other files in this patch.  Let's keep them
unified please.

thanks,

greg k-h

Re: [PATCH v2 2/3] status: Add user space API definitions for VSTATUS, NOKERNINFO and TIOCSTAT

[Greg KH]

On Sun, Feb 06, 2022 at 07:48:53AM -0800, Walt Drummond wrote:
> Add definitions for the VSTATUS control character, and the NOKERNINFO
> local control flag in the termios struct, and add an ioctl number for
> the ioctl TIOCSTAT.  Also add a default VSTATUS character (Ctrl-T)
> default valuses in termios.c_cc.  Do this for all architectures.
> 
> Signed-off-by: Walt Drummond <walt@drummond.us>
> ---
>  arch/alpha/include/asm/termios.h         | 4 ++--
>  arch/alpha/include/uapi/asm/ioctls.h     | 1 +
>  arch/alpha/include/uapi/asm/termbits.h   | 2 ++
>  arch/ia64/include/asm/termios.h          | 4 ++--
>  arch/ia64/include/uapi/asm/termbits.h    | 2 ++
>  arch/mips/include/asm/termios.h          | 4 ++--
>  arch/mips/include/uapi/asm/ioctls.h      | 1 +
>  arch/mips/include/uapi/asm/termbits.h    | 2 ++
>  arch/parisc/include/asm/termios.h        | 4 ++--
>  arch/parisc/include/uapi/asm/ioctls.h    | 1 +
>  arch/parisc/include/uapi/asm/termbits.h  | 2 ++
>  arch/powerpc/include/asm/termios.h       | 4 ++--
>  arch/powerpc/include/uapi/asm/ioctls.h   | 2 ++
>  arch/powerpc/include/uapi/asm/termbits.h | 2 ++
>  arch/s390/include/asm/termios.h          | 4 ++--
>  arch/sh/include/uapi/asm/ioctls.h        | 1 +
>  arch/sparc/include/uapi/asm/ioctls.h     | 1 +
>  arch/sparc/include/uapi/asm/termbits.h   | 2 ++
>  arch/xtensa/include/uapi/asm/ioctls.h    | 1 +
>  include/asm-generic/termios.h            | 4 ++--
>  include/uapi/asm-generic/ioctls.h        | 1 +
>  include/uapi/asm-generic/termbits.h      | 2 ++
>  22 files changed, 37 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
> index b7c77bb1bfd2..d28ddc649286 100644
> --- a/arch/alpha/include/asm/termios.h
> +++ b/arch/alpha/include/asm/termios.h
> @@ -8,9 +8,9 @@
>  	werase=^W	kill=^U		reprint=^R	sxtc=\0
>  	intr=^C		quit=^\		susp=^Z		<OSF/1 VDSUSP>
>  	start=^Q	stop=^S		lnext=^V	discard=^U
> -	vmin=\1		vtime=\0
> +	vmin=\1		vtime=\0        status=^T
>  */
> -#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000"
> +#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000\024"
>  
>  /*
>   * Translate a "termio" structure into a "termios". Ugh.
> diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
> index 971311605288..70fdeab2b5f2 100644
> --- a/arch/alpha/include/uapi/asm/ioctls.h
> +++ b/arch/alpha/include/uapi/asm/ioctls.h
> @@ -124,5 +124,6 @@
>  
>  #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
> +#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
>  
>  #endif /* _ASM_ALPHA_IOCTLS_H */
> diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
> index 4575ba34a0ea..9a1b9aa92d29 100644
> --- a/arch/alpha/include/uapi/asm/termbits.h
> +++ b/arch/alpha/include/uapi/asm/termbits.h
> @@ -70,6 +70,7 @@ struct ktermios {
>  #define VDISCARD 15
>  #define VMIN 16
>  #define VTIME 17
> +#define VSTATUS 18
>  
>  /* c_iflag bits */
>  #define IGNBRK	0000001
> @@ -203,6 +204,7 @@ struct ktermios {
>  #define PENDIN	0x20000000
>  #define IEXTEN	0x00000400
>  #define EXTPROC	0x10000000
> +#define NOKERNINFO 0x40000000

Here, and elsewhere, you seem to mix tabs and spaces.  Please use what
is in the original file (tabs here.)

>  /* Values for the ACTION argument to `tcflow'.  */
>  #define	TCOOFF		0
> diff --git a/arch/ia64/include/asm/termios.h b/arch/ia64/include/asm/termios.h
> index 589c026444cc..40e83f9b6ead 100644
> --- a/arch/ia64/include/asm/termios.h
> +++ b/arch/ia64/include/asm/termios.h
> @@ -15,9 +15,9 @@
>  	eof=^D		vtime=\0	vmin=\1		sxtc=\0
>  	start=^Q	stop=^S		susp=^Z		eol=\0
>  	reprint=^R	discard=^U	werase=^W	lnext=^V
> -	eol2=\0
> +	eol2=\0         status=^T

Same here.  And for the other files in this patch.  Let's keep them
unified please.

thanks,

greg k-h

Re: [PATCH v2 2/3] status: Add user space API definitions for VSTATUS, NOKERNINFO and TIOCSTAT

[Greg KH]

On Sun, Feb 06, 2022 at 07:48:53AM -0800, Walt Drummond wrote:
> Add definitions for the VSTATUS control character, and the NOKERNINFO
> local control flag in the termios struct, and add an ioctl number for
> the ioctl TIOCSTAT.  Also add a default VSTATUS character (Ctrl-T)
> default valuses in termios.c_cc.  Do this for all architectures.
> 
> Signed-off-by: Walt Drummond <walt@drummond.us>
> ---
>  arch/alpha/include/asm/termios.h         | 4 ++--
>  arch/alpha/include/uapi/asm/ioctls.h     | 1 +
>  arch/alpha/include/uapi/asm/termbits.h   | 2 ++
>  arch/ia64/include/asm/termios.h          | 4 ++--
>  arch/ia64/include/uapi/asm/termbits.h    | 2 ++
>  arch/mips/include/asm/termios.h          | 4 ++--
>  arch/mips/include/uapi/asm/ioctls.h      | 1 +
>  arch/mips/include/uapi/asm/termbits.h    | 2 ++
>  arch/parisc/include/asm/termios.h        | 4 ++--
>  arch/parisc/include/uapi/asm/ioctls.h    | 1 +
>  arch/parisc/include/uapi/asm/termbits.h  | 2 ++
>  arch/powerpc/include/asm/termios.h       | 4 ++--
>  arch/powerpc/include/uapi/asm/ioctls.h   | 2 ++
>  arch/powerpc/include/uapi/asm/termbits.h | 2 ++
>  arch/s390/include/asm/termios.h          | 4 ++--
>  arch/sh/include/uapi/asm/ioctls.h        | 1 +
>  arch/sparc/include/uapi/asm/ioctls.h     | 1 +
>  arch/sparc/include/uapi/asm/termbits.h   | 2 ++
>  arch/xtensa/include/uapi/asm/ioctls.h    | 1 +
>  include/asm-generic/termios.h            | 4 ++--
>  include/uapi/asm-generic/ioctls.h        | 1 +
>  include/uapi/asm-generic/termbits.h      | 2 ++
>  22 files changed, 37 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
> index b7c77bb1bfd2..d28ddc649286 100644
> --- a/arch/alpha/include/asm/termios.h
> +++ b/arch/alpha/include/asm/termios.h
> @@ -8,9 +8,9 @@
>  	werase=^W	kill=^U		reprint=^R	sxtc=\0
>  	intr=^C		quit=^\		susp=^Z		<OSF/1 VDSUSP>
>  	start=^Q	stop=^S		lnext=^V	discard=^U
> -	vmin=\1		vtime=\0
> +	vmin=\1		vtime=\0        status=^T
>  */
> -#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000"
> +#define INIT_C_CC "\004\000\000\177\027\025\022\000\003\034\032\000\021\023\026\025\001\000\024"
>  
>  /*
>   * Translate a "termio" structure into a "termios". Ugh.
> diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
> index 971311605288..70fdeab2b5f2 100644
> --- a/arch/alpha/include/uapi/asm/ioctls.h
> +++ b/arch/alpha/include/uapi/asm/ioctls.h
> @@ -124,5 +124,6 @@
>  
>  #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
> +#define TIOCSTAT	_IO('T', 0x5E)	/* display process group stats on tty */
>  
>  #endif /* _ASM_ALPHA_IOCTLS_H */
> diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
> index 4575ba34a0ea..9a1b9aa92d29 100644
> --- a/arch/alpha/include/uapi/asm/termbits.h
> +++ b/arch/alpha/include/uapi/asm/termbits.h
> @@ -70,6 +70,7 @@ struct ktermios {
>  #define VDISCARD 15
>  #define VMIN 16
>  #define VTIME 17
> +#define VSTATUS 18
>  
>  /* c_iflag bits */
>  #define IGNBRK	0000001
> @@ -203,6 +204,7 @@ struct ktermios {
>  #define PENDIN	0x20000000
>  #define IEXTEN	0x00000400
>  #define EXTPROC	0x10000000
> +#define NOKERNINFO 0x40000000

Here, and elsewhere, you seem to mix tabs and spaces.  Please use what
is in the original file (tabs here.)

>  /* Values for the ACTION argument to `tcflow'.  */
>  #define	TCOOFF		0
> diff --git a/arch/ia64/include/asm/termios.h b/arch/ia64/include/asm/termios.h
> index 589c026444cc..40e83f9b6ead 100644
> --- a/arch/ia64/include/asm/termios.h
> +++ b/arch/ia64/include/asm/termios.h
> @@ -15,9 +15,9 @@
>  	eof=^D		vtime=\0	vmin=\1		sxtc=\0
>  	start=^Q	stop=^S		susp=^Z		eol=\0
>  	reprint=^R	discard=^U	werase=^W	lnext=^V
> -	eol2=\0
> +	eol2=\0         status=^T

Same here.  And for the other files in this patch.  Let's keep them
unified please.

thanks,

greg k-h

Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Greg KH]

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 <walt@drummond.us>
> ---
>  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 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 000000000000..f0e053651368
> --- /dev/null
> +++ b/drivers/tty/n_tty_status.c
> @@ -0,0 +1,181 @@
> +// SPDX-License-Identifier: GPL-1.0+

We can not take GPL-1.0 code into the kernel anymore, sorry.  Please
consider using a sane license :)


> +/*
> + * 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>
> +#include <linux/sched/mm.h>
> +
> +/* Convert nanoseconds into centiseconds */
> +static inline long ns_to_cs(long l)
> +{
> +	return l / (NSEC_PER_MSEC * 10);
> +
> +}

Unneded blank line.


> +
> +/* We want the pid from the context of session */
> +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
> +{
> +	struct pid_namespace *ns;
> +
> +	spin_lock_irq(&tty->ctrl.lock);
> +	ns = ns_of_pid(tty->ctrl.session);
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
> +}
> +
> +/* This is the same odd "bitmap" described in
> + * fs/proc/array.c:get_task_state().  Consistency with standard
> + * implementations of VSTATUS requires a different set of state
> + * names.
> + */
> +static const char * const task_state_name_array[] = {
> +	"running",
> +	"sleeping",
> +	"disk sleep",
> +	"stopped",
> +	"tracing stop",
> +	"dead",
> +	"zombie",
> +	"parked",
> +	"idle",
> +};

How often is this going to get out-of-sync?  Should we use a real
enumerated type here?  Put the string somewhere else to keep this only
in one place?


> +
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));

What is this protecting from?  What is going to change that requires
this to be increased?

> +	return task_state_name_array[task_state_index(tsk)];
> +}
> +
> +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 tty_struct *tty)
> +{
> +	struct task_struct *new, *winner = NULL;
> +
> +	read_lock(&tasklist_lock);
> +	spin_lock_irq(&tty->ctrl.lock);
> +
> +	do_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new) {
> +		winner = compare(new, winner);
> +	} while_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new);
> +
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	if (winner)
> +		winner = get_task_struct(winner);
> +
> +	read_unlock(&tasklist_lock);
> +
> +	return winner;
> +}


What are these two functions trying to do?  A comment would be nice to
give us a hint as I am guessing I am going to have to maintain this for
forever :)

> +
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
> +{
> +	struct task_struct *p;
> +	struct mm_struct *mm;
> +	struct rusage rusage;
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct timespec64 utime, stime, rtime;
> +	char tname[TASK_COMM_LEN];
> +	unsigned int pid;
> +	char *state;
> +	unsigned long rss = 0;
> +	size_t len = 0;
> +
> +	get_avenrun(loadavg, FIXED_1/200, 0);

Why 200?

> +	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;
> +	}
> +
> +	/* Note that if p is refcounted */
> +	p = pick_process(tty);
> +	if (p == NULL) {
> +		len += scnprintf(msg + len, msglen - len,
> +				 "empty foreground process group\n");
> +		goto out;
> +	}
> +
> +	mm = get_task_mm(p);
> +	if (mm) {
> +		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
> +		mmput(mm);
> +	}
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	pid = __get_pid(p, tty);
> +	state = (char *) get_task_state_name(p);
> +	wallclock = ktime_get_ns() - p->start_time;
> +	put_task_struct(p);
> +
> +	/* After this point, any of the information we have on p might
> +	 * become stale.  It's OK if the status message is a little bit
> +	 * lossy.
> +	 */
> +
> +	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,	pid, state,
> +			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
> +			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
> +			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
> +			 pcpu, rss);
> +
> +out:
> +	return len;
> +}
> 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 cbe5d535a69d..2e483708608c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,7 @@
>  #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))
> @@ -114,6 +115,7 @@
>  #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;
> @@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
>  static inline void n_tty_init(void) { }
>  #endif
>  
> +/* n_tty_status.c */
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);

No need for this to be in include/linux/tty.h, put it in the .h file in
drivers/tty/ please.

thanks,

greg k-h

Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Greg KH]

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 <walt@drummond.us>
> ---
>  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 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 000000000000..f0e053651368
> --- /dev/null
> +++ b/drivers/tty/n_tty_status.c
> @@ -0,0 +1,181 @@
> +// SPDX-License-Identifier: GPL-1.0+

We can not take GPL-1.0 code into the kernel anymore, sorry.  Please
consider using a sane license :)


> +/*
> + * 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>
> +#include <linux/sched/mm.h>
> +
> +/* Convert nanoseconds into centiseconds */
> +static inline long ns_to_cs(long l)
> +{
> +	return l / (NSEC_PER_MSEC * 10);
> +
> +}

Unneded blank line.


> +
> +/* We want the pid from the context of session */
> +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
> +{
> +	struct pid_namespace *ns;
> +
> +	spin_lock_irq(&tty->ctrl.lock);
> +	ns = ns_of_pid(tty->ctrl.session);
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
> +}
> +
> +/* This is the same odd "bitmap" described in
> + * fs/proc/array.c:get_task_state().  Consistency with standard
> + * implementations of VSTATUS requires a different set of state
> + * names.
> + */
> +static const char * const task_state_name_array[] = {
> +	"running",
> +	"sleeping",
> +	"disk sleep",
> +	"stopped",
> +	"tracing stop",
> +	"dead",
> +	"zombie",
> +	"parked",
> +	"idle",
> +};

How often is this going to get out-of-sync?  Should we use a real
enumerated type here?  Put the string somewhere else to keep this only
in one place?


> +
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));

What is this protecting from?  What is going to change that requires
this to be increased?

> +	return task_state_name_array[task_state_index(tsk)];
> +}
> +
> +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 tty_struct *tty)
> +{
> +	struct task_struct *new, *winner = NULL;
> +
> +	read_lock(&tasklist_lock);
> +	spin_lock_irq(&tty->ctrl.lock);
> +
> +	do_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new) {
> +		winner = compare(new, winner);
> +	} while_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new);
> +
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	if (winner)
> +		winner = get_task_struct(winner);
> +
> +	read_unlock(&tasklist_lock);
> +
> +	return winner;
> +}


What are these two functions trying to do?  A comment would be nice to
give us a hint as I am guessing I am going to have to maintain this for
forever :)

> +
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
> +{
> +	struct task_struct *p;
> +	struct mm_struct *mm;
> +	struct rusage rusage;
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct timespec64 utime, stime, rtime;
> +	char tname[TASK_COMM_LEN];
> +	unsigned int pid;
> +	char *state;
> +	unsigned long rss = 0;
> +	size_t len = 0;
> +
> +	get_avenrun(loadavg, FIXED_1/200, 0);

Why 200?

> +	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;
> +	}
> +
> +	/* Note that if p is refcounted */
> +	p = pick_process(tty);
> +	if (p == NULL) {
> +		len += scnprintf(msg + len, msglen - len,
> +				 "empty foreground process group\n");
> +		goto out;
> +	}
> +
> +	mm = get_task_mm(p);
> +	if (mm) {
> +		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
> +		mmput(mm);
> +	}
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	pid = __get_pid(p, tty);
> +	state = (char *) get_task_state_name(p);
> +	wallclock = ktime_get_ns() - p->start_time;
> +	put_task_struct(p);
> +
> +	/* After this point, any of the information we have on p might
> +	 * become stale.  It's OK if the status message is a little bit
> +	 * lossy.
> +	 */
> +
> +	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,	pid, state,
> +			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
> +			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
> +			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
> +			 pcpu, rss);
> +
> +out:
> +	return len;
> +}
> 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 cbe5d535a69d..2e483708608c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,7 @@
>  #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))
> @@ -114,6 +115,7 @@
>  #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;
> @@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
>  static inline void n_tty_init(void) { }
>  #endif
>  
> +/* n_tty_status.c */
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);

No need for this to be in include/linux/tty.h, put it in the .h file in
drivers/tty/ please.

thanks,

greg k-h

Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed o

[Greg KH]

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 <walt@drummond.us>
> ---
>  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 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 000000000000..f0e053651368
> --- /dev/null
> +++ b/drivers/tty/n_tty_status.c
> @@ -0,0 +1,181 @@
> +// SPDX-License-Identifier: GPL-1.0+

We can not take GPL-1.0 code into the kernel anymore, sorry.  Please
consider using a sane license :)


> +/*
> + * 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>
> +#include <linux/sched/mm.h>
> +
> +/* Convert nanoseconds into centiseconds */
> +static inline long ns_to_cs(long l)
> +{
> +	return l / (NSEC_PER_MSEC * 10);
> +
> +}

Unneded blank line.


> +
> +/* We want the pid from the context of session */
> +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
> +{
> +	struct pid_namespace *ns;
> +
> +	spin_lock_irq(&tty->ctrl.lock);
> +	ns = ns_of_pid(tty->ctrl.session);
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
> +}
> +
> +/* This is the same odd "bitmap" described in
> + * fs/proc/array.c:get_task_state().  Consistency with standard
> + * implementations of VSTATUS requires a different set of state
> + * names.
> + */
> +static const char * const task_state_name_array[] = {
> +	"running",
> +	"sleeping",
> +	"disk sleep",
> +	"stopped",
> +	"tracing stop",
> +	"dead",
> +	"zombie",
> +	"parked",
> +	"idle",
> +};

How often is this going to get out-of-sync?  Should we use a real
enumerated type here?  Put the string somewhere else to keep this only
in one place?


> +
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));

What is this protecting from?  What is going to change that requires
this to be increased?

> +	return task_state_name_array[task_state_index(tsk)];
> +}
> +
> +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 tty_struct *tty)
> +{
> +	struct task_struct *new, *winner = NULL;
> +
> +	read_lock(&tasklist_lock);
> +	spin_lock_irq(&tty->ctrl.lock);
> +
> +	do_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new) {
> +		winner = compare(new, winner);
> +	} while_each_pid_task(tty->ctrl.pgrp, PIDTYPE_PGID, new);
> +
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	if (winner)
> +		winner = get_task_struct(winner);
> +
> +	read_unlock(&tasklist_lock);
> +
> +	return winner;
> +}


What are these two functions trying to do?  A comment would be nice to
give us a hint as I am guessing I am going to have to maintain this for
forever :)

> +
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
> +{
> +	struct task_struct *p;
> +	struct mm_struct *mm;
> +	struct rusage rusage;
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct timespec64 utime, stime, rtime;
> +	char tname[TASK_COMM_LEN];
> +	unsigned int pid;
> +	char *state;
> +	unsigned long rss = 0;
> +	size_t len = 0;
> +
> +	get_avenrun(loadavg, FIXED_1/200, 0);

Why 200?

> +	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;
> +	}
> +
> +	/* Note that if p is refcounted */
> +	p = pick_process(tty);
> +	if (p = NULL) {
> +		len += scnprintf(msg + len, msglen - len,
> +				 "empty foreground process group\n");
> +		goto out;
> +	}
> +
> +	mm = get_task_mm(p);
> +	if (mm) {
> +		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
> +		mmput(mm);
> +	}
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	pid = __get_pid(p, tty);
> +	state = (char *) get_task_state_name(p);
> +	wallclock = ktime_get_ns() - p->start_time;
> +	put_task_struct(p);
> +
> +	/* After this point, any of the information we have on p might
> +	 * become stale.  It's OK if the status message is a little bit
> +	 * lossy.
> +	 */
> +
> +	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,	pid, state,
> +			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
> +			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
> +			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
> +			 pcpu, rss);
> +
> +out:
> +	return len;
> +}
> 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 cbe5d535a69d..2e483708608c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,7 @@
>  #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))
> @@ -114,6 +115,7 @@
>  #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;
> @@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
>  static inline void n_tty_init(void) { }
>  #endif
>  
> +/* n_tty_status.c */
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);

No need for this to be in include/linux/tty.h, put it in the .h file in
drivers/tty/ please.

thanks,

greg k-h

Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Arseny Maslennikov]

[-- Attachment #1: Type: text/plain, Size: 11305 bytes --]

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
> 
> 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 <walt@drummond.us>
> ---
>  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
> 
> <...>
> @@ -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:

Perhaps we want to guard this (example pseudocode follows):

		if (*our ldisc is not n_tty*)
			return an error like -ENOTTY;

...since kerninfo is useless for non-UI ttys, e. g. serial device
drivers, and this ioctl could mess them up if this code path can be
taken. (I have not verified this kind of breakage is possible.) Please
see the complete rationale below, this paragraph is an illustrational
note for it.

> +		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 000000000000..f0e053651368
> --- /dev/null
> +++ b/drivers/tty/n_tty_status.c
> @@ -0,0 +1,181 @@
> +// 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>
> +#include <linux/sched/mm.h>
> +
> +/* Convert nanoseconds into centiseconds */
> +static inline long ns_to_cs(long l)
> +{
> +	return l / (NSEC_PER_MSEC * 10);
> +
> +}
> +
> +/* We want the pid from the context of session */
> +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
> +{
> +	struct pid_namespace *ns;
> +
> +	spin_lock_irq(&tty->ctrl.lock);
> +	ns = ns_of_pid(tty->ctrl.session);
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
> +}
> +
> +/* This is the same odd "bitmap" described in
> + * fs/proc/array.c:get_task_state().  Consistency with standard
> + * implementations of VSTATUS requires a different set of state
> + * names.

As far as I can remember, VSTATUS is not subject to any standard, so no
implementation is *standard* by any means. The 2 most popular libre &
open source BSD derivatives implement the VSTATUS message with different
details (e. g. OpenBSD does not check for column 0, FreeBSD does) and
use different message formats.
We are not obliged to copy the message format or the task state names
from another system (which most likely uses a different set of task
states, or might change its task state set independently of Linux),
especially since the message is not part of any API and is not even
readable by processes who read or write on the terminal.

(If the terminal is a pty, then there is a user process which has
possession of an fd to the pty master, but anyway it can not — and
should not — distinguish between terminal output produced by processes
or by the ldisc.)

> + */
> +static const char * const task_state_name_array[] = {
> +	"running",
> +	"sleeping",
> +	"disk sleep",
> +	"stopped",
> +	"tracing stop",
> +	"dead",
> +	"zombie",
> +	"parked",
> +	"idle",
> +};
> +
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));
> +	return task_state_name_array[task_state_index(tsk)];
> +}
> +
> <...>
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
> +{
> +	struct task_struct *p;
> +	struct mm_struct *mm;
> +	struct rusage rusage;
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct timespec64 utime, stime, rtime;
> +	char tname[TASK_COMM_LEN];
> +	unsigned int pid;
> +	char *state;
> +	unsigned long rss = 0;
> +	size_t len = 0;
> +
> +	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;
> +	}
> +
> +	/* Note that if p is refcounted */
> +	p = pick_process(tty);
> +	if (p == NULL) {
> +		len += scnprintf(msg + len, msglen - len,
> +				 "empty foreground process group\n");
> +		goto out;
> +	}
> +
> +	mm = get_task_mm(p);
> +	if (mm) {
> +		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
> +		mmput(mm);
> +	}
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	pid = __get_pid(p, tty);
> +	state = (char *) get_task_state_name(p);
> +	wallclock = ktime_get_ns() - p->start_time;
> +	put_task_struct(p);
> +
> +	/* After this point, any of the information we have on p might
> +	 * become stale.  It's OK if the status message is a little bit
> +	 * lossy.
> +	 */

...By the moment the user sees the status message, the presented
information is a bit stale anyway, but still relevant. :)

> +
> +	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);

Other reviewers have mentioned that this number does not make too much
sense, as we can see the dividend and the divisor in the message. It
would make more sense to display CPU consumption by the process in a
recent enough time window, or some other "hogginess" estimate, but I
doubt this information is available.

> +
> +	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,	pid, state,
> +			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
> +			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
> +			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
> +			 pcpu, rss);
> +
> +out:
> +	return len;
> +}
> 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,

Does this mean that nokerninfo is on by default? Do we have a reason to
do that?

As of this patch we require icanon and iexten to be set for the message
to be composed and printed. An experiment shows PTY encapsulation
programs like openssh turn off both those flags on the tty they run on
before they take control (contrary to what has been said in LWN), so
they are unimpacted.

The termios(3) page from man-pages states:
   Raw mode
       cfmakeraw() sets the terminal to something like the "raw"  mode
       of  the old Version 7 terminal driver: input is available char‐
       acter by character, echoing is disabled, and all  special  pro‐
       cessing  of  terminal  input and output characters is disabled.
       The terminal attributes are set as follows:

           termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                           | INLCR | IGNCR | ICRNL | IXON);
           termios_p->c_oflag &= ~OPOST;
           termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
           termios_p->c_cflag &= ~(CSIZE | PARENB);
           termios_p->c_cflag |= CS8;

So any program which uses this API effectively turns off kerninfo as
implemented here.

There are 2 ways n_tty_status() can be called as of this patch: either
from inside n_tty or via TIOCSTAT. The first path can't be taken on ttys
whose ldisc is not N_TTY, the second path we can fix as proposed in the
comment to the TIOCSTAT hunk if needed. IOW, we can make this safe for
device drivers.

Given all this, is there any other reason to enable nokerninfo (i. e.
disable status message) by default?

>  	.c_cc = INIT_C_CC,
>  	.c_ispeed = 38400,
>  	.c_ospeed = 38400,
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index cbe5d535a69d..2e483708608c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,7 @@
>  #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))
> @@ -114,6 +115,7 @@
>  #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;
> @@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
>  static inline void n_tty_init(void) { }
>  #endif
>  
> +/* n_tty_status.c */
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);
> +
>  /* tty_audit.c */
>  #ifdef CONFIG_AUDIT
>  extern void tty_audit_exit(void);
> -- 
> 2.30.2

Thanks!

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Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Arseny Maslennikov]

[-- Attachment #1: Type: text/plain, Size: 11305 bytes --]

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
> 
> 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 <walt@drummond.us>
> ---
>  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
> 
> <...>
> @@ -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:

Perhaps we want to guard this (example pseudocode follows):

		if (*our ldisc is not n_tty*)
			return an error like -ENOTTY;

...since kerninfo is useless for non-UI ttys, e. g. serial device
drivers, and this ioctl could mess them up if this code path can be
taken. (I have not verified this kind of breakage is possible.) Please
see the complete rationale below, this paragraph is an illustrational
note for it.

> +		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 000000000000..f0e053651368
> --- /dev/null
> +++ b/drivers/tty/n_tty_status.c
> @@ -0,0 +1,181 @@
> +// 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>
> +#include <linux/sched/mm.h>
> +
> +/* Convert nanoseconds into centiseconds */
> +static inline long ns_to_cs(long l)
> +{
> +	return l / (NSEC_PER_MSEC * 10);
> +
> +}
> +
> +/* We want the pid from the context of session */
> +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
> +{
> +	struct pid_namespace *ns;
> +
> +	spin_lock_irq(&tty->ctrl.lock);
> +	ns = ns_of_pid(tty->ctrl.session);
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
> +}
> +
> +/* This is the same odd "bitmap" described in
> + * fs/proc/array.c:get_task_state().  Consistency with standard
> + * implementations of VSTATUS requires a different set of state
> + * names.

As far as I can remember, VSTATUS is not subject to any standard, so no
implementation is *standard* by any means. The 2 most popular libre &
open source BSD derivatives implement the VSTATUS message with different
details (e. g. OpenBSD does not check for column 0, FreeBSD does) and
use different message formats.
We are not obliged to copy the message format or the task state names
from another system (which most likely uses a different set of task
states, or might change its task state set independently of Linux),
especially since the message is not part of any API and is not even
readable by processes who read or write on the terminal.

(If the terminal is a pty, then there is a user process which has
possession of an fd to the pty master, but anyway it can not — and
should not — distinguish between terminal output produced by processes
or by the ldisc.)

> + */
> +static const char * const task_state_name_array[] = {
> +	"running",
> +	"sleeping",
> +	"disk sleep",
> +	"stopped",
> +	"tracing stop",
> +	"dead",
> +	"zombie",
> +	"parked",
> +	"idle",
> +};
> +
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));
> +	return task_state_name_array[task_state_index(tsk)];
> +}
> +
> <...>
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
> +{
> +	struct task_struct *p;
> +	struct mm_struct *mm;
> +	struct rusage rusage;
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct timespec64 utime, stime, rtime;
> +	char tname[TASK_COMM_LEN];
> +	unsigned int pid;
> +	char *state;
> +	unsigned long rss = 0;
> +	size_t len = 0;
> +
> +	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;
> +	}
> +
> +	/* Note that if p is refcounted */
> +	p = pick_process(tty);
> +	if (p == NULL) {
> +		len += scnprintf(msg + len, msglen - len,
> +				 "empty foreground process group\n");
> +		goto out;
> +	}
> +
> +	mm = get_task_mm(p);
> +	if (mm) {
> +		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
> +		mmput(mm);
> +	}
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	pid = __get_pid(p, tty);
> +	state = (char *) get_task_state_name(p);
> +	wallclock = ktime_get_ns() - p->start_time;
> +	put_task_struct(p);
> +
> +	/* After this point, any of the information we have on p might
> +	 * become stale.  It's OK if the status message is a little bit
> +	 * lossy.
> +	 */

...By the moment the user sees the status message, the presented
information is a bit stale anyway, but still relevant. :)

> +
> +	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);

Other reviewers have mentioned that this number does not make too much
sense, as we can see the dividend and the divisor in the message. It
would make more sense to display CPU consumption by the process in a
recent enough time window, or some other "hogginess" estimate, but I
doubt this information is available.

> +
> +	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,	pid, state,
> +			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
> +			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
> +			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
> +			 pcpu, rss);
> +
> +out:
> +	return len;
> +}
> 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,

Does this mean that nokerninfo is on by default? Do we have a reason to
do that?

As of this patch we require icanon and iexten to be set for the message
to be composed and printed. An experiment shows PTY encapsulation
programs like openssh turn off both those flags on the tty they run on
before they take control (contrary to what has been said in LWN), so
they are unimpacted.

The termios(3) page from man-pages states:
   Raw mode
       cfmakeraw() sets the terminal to something like the "raw"  mode
       of  the old Version 7 terminal driver: input is available char‐
       acter by character, echoing is disabled, and all  special  pro‐
       cessing  of  terminal  input and output characters is disabled.
       The terminal attributes are set as follows:

           termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                           | INLCR | IGNCR | ICRNL | IXON);
           termios_p->c_oflag &= ~OPOST;
           termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
           termios_p->c_cflag &= ~(CSIZE | PARENB);
           termios_p->c_cflag |= CS8;

So any program which uses this API effectively turns off kerninfo as
implemented here.

There are 2 ways n_tty_status() can be called as of this patch: either
from inside n_tty or via TIOCSTAT. The first path can't be taken on ttys
whose ldisc is not N_TTY, the second path we can fix as proposed in the
comment to the TIOCSTAT hunk if needed. IOW, we can make this safe for
device drivers.

Given all this, is there any other reason to enable nokerninfo (i. e.
disable status message) by default?

>  	.c_cc = INIT_C_CC,
>  	.c_ispeed = 38400,
>  	.c_ospeed = 38400,
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index cbe5d535a69d..2e483708608c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,7 @@
>  #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))
> @@ -114,6 +115,7 @@
>  #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;
> @@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
>  static inline void n_tty_init(void) { }
>  #endif
>  
> +/* n_tty_status.c */
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);
> +
>  /* tty_audit.c */
>  #ifdef CONFIG_AUDIT
>  extern void tty_audit_exit(void);
> -- 
> 2.30.2

Thanks!

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Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed o

[Arseny Maslennikov]

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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
> 
> 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 <walt@drummond.us>
> ---
>  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
> 
> <...>
> @@ -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:

Perhaps we want to guard this (example pseudocode follows):

		if (*our ldisc is not n_tty*)
			return an error like -ENOTTY;

...since kerninfo is useless for non-UI ttys, e. g. serial device
drivers, and this ioctl could mess them up if this code path can be
taken. (I have not verified this kind of breakage is possible.) Please
see the complete rationale below, this paragraph is an illustrational
note for it.

> +		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 000000000000..f0e053651368
> --- /dev/null
> +++ b/drivers/tty/n_tty_status.c
> @@ -0,0 +1,181 @@
> +// 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>
> +#include <linux/sched/mm.h>
> +
> +/* Convert nanoseconds into centiseconds */
> +static inline long ns_to_cs(long l)
> +{
> +	return l / (NSEC_PER_MSEC * 10);
> +
> +}
> +
> +/* We want the pid from the context of session */
> +static inline pid_t __get_pid(struct task_struct *tsk, struct tty_struct *tty)
> +{
> +	struct pid_namespace *ns;
> +
> +	spin_lock_irq(&tty->ctrl.lock);
> +	ns = ns_of_pid(tty->ctrl.session);
> +	spin_unlock_irq(&tty->ctrl.lock);
> +
> +	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
> +}
> +
> +/* This is the same odd "bitmap" described in
> + * fs/proc/array.c:get_task_state().  Consistency with standard
> + * implementations of VSTATUS requires a different set of state
> + * names.

As far as I can remember, VSTATUS is not subject to any standard, so no
implementation is *standard* by any means. The 2 most popular libre &
open source BSD derivatives implement the VSTATUS message with different
details (e. g. OpenBSD does not check for column 0, FreeBSD does) and
use different message formats.
We are not obliged to copy the message format or the task state names
from another system (which most likely uses a different set of task
states, or might change its task state set independently of Linux),
especially since the message is not part of any API and is not even
readable by processes who read or write on the terminal.

(If the terminal is a pty, then there is a user process which has
possession of an fd to the pty master, but anyway it can not — and
should not — distinguish between terminal output produced by processes
or by the ldisc.)

> + */
> +static const char * const task_state_name_array[] = {
> +	"running",
> +	"sleeping",
> +	"disk sleep",
> +	"stopped",
> +	"tracing stop",
> +	"dead",
> +	"zombie",
> +	"parked",
> +	"idle",
> +};
> +
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_name_array));
> +	return task_state_name_array[task_state_index(tsk)];
> +}
> +
> <...>
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen)
> +{
> +	struct task_struct *p;
> +	struct mm_struct *mm;
> +	struct rusage rusage;
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct timespec64 utime, stime, rtime;
> +	char tname[TASK_COMM_LEN];
> +	unsigned int pid;
> +	char *state;
> +	unsigned long rss = 0;
> +	size_t len = 0;
> +
> +	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;
> +	}
> +
> +	/* Note that if p is refcounted */
> +	p = pick_process(tty);
> +	if (p == NULL) {
> +		len += scnprintf(msg + len, msglen - len,
> +				 "empty foreground process group\n");
> +		goto out;
> +	}
> +
> +	mm = get_task_mm(p);
> +	if (mm) {
> +		rss = get_mm_rss(mm) * PAGE_SIZE / 1024;
> +		mmput(mm);
> +	}
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	pid = __get_pid(p, tty);
> +	state = (char *) get_task_state_name(p);
> +	wallclock = ktime_get_ns() - p->start_time;
> +	put_task_struct(p);
> +
> +	/* After this point, any of the information we have on p might
> +	 * become stale.  It's OK if the status message is a little bit
> +	 * lossy.
> +	 */

...By the moment the user sees the status message, the presented
information is a bit stale anyway, but still relevant. :)

> +
> +	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);

Other reviewers have mentioned that this number does not make too much
sense, as we can see the dividend and the divisor in the message. It
would make more sense to display CPU consumption by the process in a
recent enough time window, or some other "hogginess" estimate, but I
doubt this information is available.

> +
> +	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,	pid, state,
> +			 rtime.tv_sec, ns_to_cs(rtime.tv_nsec),
> +			 utime.tv_sec, ns_to_cs(utime.tv_nsec),
> +			 stime.tv_sec, ns_to_cs(stime.tv_nsec),
> +			 pcpu, rss);
> +
> +out:
> +	return len;
> +}
> 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,

Does this mean that nokerninfo is on by default? Do we have a reason to
do that?

As of this patch we require icanon and iexten to be set for the message
to be composed and printed. An experiment shows PTY encapsulation
programs like openssh turn off both those flags on the tty they run on
before they take control (contrary to what has been said in LWN), so
they are unimpacted.

The termios(3) page from man-pages states:
   Raw mode
       cfmakeraw() sets the terminal to something like the "raw"  mode
       of  the old Version 7 terminal driver: input is available char‐
       acter by character, echoing is disabled, and all  special  pro‐
       cessing  of  terminal  input and output characters is disabled.
       The terminal attributes are set as follows:

           termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                           | INLCR | IGNCR | ICRNL | IXON);
           termios_p->c_oflag &= ~OPOST;
           termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
           termios_p->c_cflag &= ~(CSIZE | PARENB);
           termios_p->c_cflag |= CS8;

So any program which uses this API effectively turns off kerninfo as
implemented here.

There are 2 ways n_tty_status() can be called as of this patch: either
from inside n_tty or via TIOCSTAT. The first path can't be taken on ttys
whose ldisc is not N_TTY, the second path we can fix as proposed in the
comment to the TIOCSTAT hunk if needed. IOW, we can make this safe for
device drivers.

Given all this, is there any other reason to enable nokerninfo (i. e.
disable status message) by default?

>  	.c_cc = INIT_C_CC,
>  	.c_ispeed = 38400,
>  	.c_ospeed = 38400,
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index cbe5d535a69d..2e483708608c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,7 @@
>  #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))
> @@ -114,6 +115,7 @@
>  #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;
> @@ -389,6 +391,9 @@ extern void __init n_tty_init(void);
>  static inline void n_tty_init(void) { }
>  #endif
>  
> +/* n_tty_status.c */
> +size_t n_tty_get_status(struct tty_struct *tty, char *msg, size_t msglen);
> +
>  /* tty_audit.c */
>  #ifdef CONFIG_AUDIT
>  extern void tty_audit_exit(void);
> -- 
> 2.30.2

Thanks!

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Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Arseny Maslennikov]

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On Mon, Feb 07, 2022 at 12:25:21AM +0300, Arseny Maslennikov wrote:
> On Sun, Feb 06, 2022 at 07:48:54AM -0800, Walt Drummond wrote:
> > @@ -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:
> 
> Perhaps we want to guard this (example pseudocode follows):
> 
> 		if (*our ldisc is not n_tty*)
> 			return an error like -ENOTTY;
> 
> ...since kerninfo is useless for non-UI ttys, e. g. serial device
> drivers, and this ioctl could mess them up if this code path can be
> taken. (I have not verified this kind of breakage is possible.) Please
> see the complete rationale below, this paragraph is an illustrational
> note for it.

Oh wait, this *is* n_tty_ioctl(), so the ioctl is n_tty-specific. This
makes the case below even clearer.
I've been clumsy, sorry about that.

> > 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,
> 
> Does this mean that nokerninfo is on by default? Do we have a reason to
> do that?
> 
> As of this patch we require icanon and iexten to be set for the message
> to be composed and printed. An experiment shows PTY encapsulation
> programs like openssh turn off both those flags on the tty they run on
> before they take control (contrary to what has been said in LWN), so
> they are unimpacted.
> 
> The termios(3) page from man-pages states:
>    Raw mode
>        cfmakeraw() sets the terminal to something like the "raw"  mode
>        of  the old Version 7 terminal driver: input is available char‐
>        acter by character, echoing is disabled, and all  special  pro‐
>        cessing  of  terminal  input and output characters is disabled.
>        The terminal attributes are set as follows:
> 
>            termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
>                            | INLCR | IGNCR | ICRNL | IXON);
>            termios_p->c_oflag &= ~OPOST;
>            termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
>            termios_p->c_cflag &= ~(CSIZE | PARENB);
>            termios_p->c_cflag |= CS8;
> 
> So any program which uses this API effectively turns off kerninfo as
> implemented here.
> 
> There are 2 ways n_tty_status() can be called as of this patch: either
> from inside n_tty or via TIOCSTAT. The first path can't be taken on ttys
> whose ldisc is not N_TTY, ...

The second path is OK as well.

> Given all this, is there any other reason to enable nokerninfo (i. e.
> disable status message) by default?

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Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Arseny Maslennikov]

[-- Attachment #1: Type: text/plain, Size: 3100 bytes --]

On Mon, Feb 07, 2022 at 12:25:21AM +0300, Arseny Maslennikov wrote:
> On Sun, Feb 06, 2022 at 07:48:54AM -0800, Walt Drummond wrote:
> > @@ -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:
> 
> Perhaps we want to guard this (example pseudocode follows):
> 
> 		if (*our ldisc is not n_tty*)
> 			return an error like -ENOTTY;
> 
> ...since kerninfo is useless for non-UI ttys, e. g. serial device
> drivers, and this ioctl could mess them up if this code path can be
> taken. (I have not verified this kind of breakage is possible.) Please
> see the complete rationale below, this paragraph is an illustrational
> note for it.

Oh wait, this *is* n_tty_ioctl(), so the ioctl is n_tty-specific. This
makes the case below even clearer.
I've been clumsy, sorry about that.

> > 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,
> 
> Does this mean that nokerninfo is on by default? Do we have a reason to
> do that?
> 
> As of this patch we require icanon and iexten to be set for the message
> to be composed and printed. An experiment shows PTY encapsulation
> programs like openssh turn off both those flags on the tty they run on
> before they take control (contrary to what has been said in LWN), so
> they are unimpacted.
> 
> The termios(3) page from man-pages states:
>    Raw mode
>        cfmakeraw() sets the terminal to something like the "raw"  mode
>        of  the old Version 7 terminal driver: input is available char‐
>        acter by character, echoing is disabled, and all  special  pro‐
>        cessing  of  terminal  input and output characters is disabled.
>        The terminal attributes are set as follows:
> 
>            termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
>                            | INLCR | IGNCR | ICRNL | IXON);
>            termios_p->c_oflag &= ~OPOST;
>            termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
>            termios_p->c_cflag &= ~(CSIZE | PARENB);
>            termios_p->c_cflag |= CS8;
> 
> So any program which uses this API effectively turns off kerninfo as
> implemented here.
> 
> There are 2 ways n_tty_status() can be called as of this patch: either
> from inside n_tty or via TIOCSTAT. The first path can't be taken on ttys
> whose ldisc is not N_TTY, ...

The second path is OK as well.

> Given all this, is there any other reason to enable nokerninfo (i. e.
> disable status message) by default?

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Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed o

[Arseny Maslennikov]

[-- Attachment #1: Type: text/plain, Size: 3100 bytes --]

On Mon, Feb 07, 2022 at 12:25:21AM +0300, Arseny Maslennikov wrote:
> On Sun, Feb 06, 2022 at 07:48:54AM -0800, Walt Drummond wrote:
> > @@ -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:
> 
> Perhaps we want to guard this (example pseudocode follows):
> 
> 		if (*our ldisc is not n_tty*)
> 			return an error like -ENOTTY;
> 
> ...since kerninfo is useless for non-UI ttys, e. g. serial device
> drivers, and this ioctl could mess them up if this code path can be
> taken. (I have not verified this kind of breakage is possible.) Please
> see the complete rationale below, this paragraph is an illustrational
> note for it.

Oh wait, this *is* n_tty_ioctl(), so the ioctl is n_tty-specific. This
makes the case below even clearer.
I've been clumsy, sorry about that.

> > 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,
> 
> Does this mean that nokerninfo is on by default? Do we have a reason to
> do that?
> 
> As of this patch we require icanon and iexten to be set for the message
> to be composed and printed. An experiment shows PTY encapsulation
> programs like openssh turn off both those flags on the tty they run on
> before they take control (contrary to what has been said in LWN), so
> they are unimpacted.
> 
> The termios(3) page from man-pages states:
>    Raw mode
>        cfmakeraw() sets the terminal to something like the "raw"  mode
>        of  the old Version 7 terminal driver: input is available char‐
>        acter by character, echoing is disabled, and all  special  pro‐
>        cessing  of  terminal  input and output characters is disabled.
>        The terminal attributes are set as follows:
> 
>            termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
>                            | INLCR | IGNCR | ICRNL | IXON);
>            termios_p->c_oflag &= ~OPOST;
>            termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
>            termios_p->c_cflag &= ~(CSIZE | PARENB);
>            termios_p->c_cflag |= CS8;
> 
> So any program which uses this API effectively turns off kerninfo as
> implemented here.
> 
> There are 2 ways n_tty_status() can be called as of this patch: either
> from inside n_tty or via TIOCSTAT. The first path can't be taken on ttys
> whose ldisc is not N_TTY, ...

The second path is OK as well.

> Given all this, is there any other reason to enable nokerninfo (i. e.
> disable status message) by default?

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Re: [PATCH v2 3/3] vstatus: Display an informational message when the VSTATUS character is pressed or TIOCSTAT ioctl is called.

[Jiri Slaby]

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 <walt@drummond.us>
> ---

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.

[Jiri Slaby]

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 <walt@drummond.us>
> ---

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 o

[Jiri Slaby]

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 <walt@drummond.us>
> ---

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