Commit d01c3289 authored by Masatake YAMATO's avatar Masatake YAMATO Committed by Greg Kroah-Hartman
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pty: show associative slave of ptmx in fdinfo 



This patch adds "tty-index" field to /proc/PID/fdinfo/N if N
specifies /dev/ptmx. The field shows the index of associative
slave pts.

Though a minor number is given for each pts instance, ptmx is not.
It means there is no way in user-space to know the association between
file descriptors for pts/n and ptmx. (n = 0, 1, ...)

This is different from pipe. About pipe such association can be solved
by inode of pipefs.

Providing the way to know the association between pts/n and ptmx helps
users understand the status of running system. lsof can utilize this field.

Signed-off-by: default avatarMasatake YAMATO <yamato@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 199e717f

drivers/tty/pty.c

+7 −1
Original line number Diff line number Diff line
@@ -741,6 +741,11 @@ static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 
	}

}



static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)

{

	seq_printf(m, "tty-index:\t%d\n", tty->index);

}



static const struct tty_operations ptm_unix98_ops = {

	.lookup = ptm_unix98_lookup,

	.install = pty_unix98_install,
@@ -755,7 +760,8 @@ static const struct tty_operations ptm_unix98_ops = { 
	.ioctl = pty_unix98_ioctl,

	.compat_ioctl = pty_unix98_compat_ioctl,

	.resize = pty_resize,

	.cleanup = pty_cleanup

	.cleanup = pty_cleanup,

	.show_fdinfo = pty_show_fdinfo,

};



static const struct tty_operations pty_unix98_ops = {

drivers/tty/tty_io.c

+9 −0
Original line number Diff line number Diff line
@@ -462,6 +462,14 @@ static int hung_up_tty_fasync(int fd, struct file *file, int on) 
	return -ENOTTY;

}



static void tty_show_fdinfo(struct seq_file *m, struct file *file)

{

	struct tty_struct *tty = file_tty(file);



	if (tty && tty->ops && tty->ops->show_fdinfo)

		tty->ops->show_fdinfo(tty, m);

}



static const struct file_operations tty_fops = {

	.llseek		= no_llseek,

	.read		= tty_read,
@@ -472,6 +480,7 @@ static const struct file_operations tty_fops = { 
	.open		= tty_open,

	.release	= tty_release,

	.fasync		= tty_fasync,

	.show_fdinfo	= tty_show_fdinfo,

};



static const struct file_operations console_fops = {

include/linux/tty_driver.h

+2 −0
Original line number Diff line number Diff line
@@ -243,6 +243,7 @@ 
#include <linux/list.h>

#include <linux/cdev.h>

#include <linux/termios.h>

#include <linux/seq_file.h>



struct tty_struct;

struct tty_driver;
@@ -285,6 +286,7 @@ struct tty_operations { 
	int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);

	int (*get_icount)(struct tty_struct *tty,

				struct serial_icounter_struct *icount);

	void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);

#ifdef CONFIG_CONSOLE_POLL

	int (*poll_init)(struct tty_driver *driver, int line, char *options);

	int (*poll_get_char)(struct tty_driver *driver, int line);

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