path: root/drivers/tty/pty.c
diff options
authorMasatake YAMATO <yamato@redhat.com>2017-07-18 06:27:59 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-28 20:51:23 +0200
commitd01c3289e7d68162e32bc08c2b65dd1a216a7ef8 (patch)
tree34177b1e85f857b838fa75b08153d091472eb775 /drivers/tty/pty.c
parent199e717f252be0e31c97b9c7861dd6e2abfaa936 (diff)
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: Masatake YAMATO <yamato@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/pty.c')
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 284749fb0f6b..bb672ace562f 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -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 = {

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