summaryrefslogtreecommitdiff
path: root/drivers/tty
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2013-05-01 07:32:21 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-07 19:51:53 -0700
commitce5b62fd947369813666074f725aa0c1d819fc29 (patch)
treea1ea9a71634b7146ea63a645db1a46aa208779d2 /drivers/tty
parent8370884e1b78a1aa1c4c80872cea22c0269b93bd (diff)
tty: fix up atime/mtime mess, take three
commit b0b885657b6c8ef63a46bc9299b2a7715d19acde upstream. We first tried to avoid updating atime/mtime entirely (commit b0de59b5733d: "TTY: do not update atime/mtime on read/write"), and then limited it to only update it occasionally (commit 37b7f3c76595: "TTY: fix atime/mtime regression"), but it turns out that this was both insufficient and overkill. It was insufficient because we let people attach to the shared ptmx node to see activity without even reading atime/mtime, and it was overkill because the "only once a minute" means that you can't really tell an idle person from an active one with 'w'. So this tries to fix the problem properly. It marks the shared ptmx node as un-notifiable, and it lowers the "only once a minute" to a few seconds instead - still long enough that you can't time individual keystrokes, but short enough that you can tell whether somebody is active or not. Reported-by: Simon Kirby <sim@hostway.ca> Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/pty.c3
-rw-r--r--drivers/tty/tty_io.c4
2 files changed, 5 insertions, 2 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 636c539cb77a..cf9a1911d4ab 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -607,6 +607,9 @@ static int ptmx_open(struct inode *inode, struct file *filp)
nonseekable_open(inode, filp);
+ /* We refuse fsnotify events on ptmx, since it's a shared resource */
+ filp->f_mode |= FMODE_NONOTIFY;
+
retval = tty_alloc_file(filp);
if (retval)
return retval;
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index bf9f98750f4f..b28d6356a142 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -938,10 +938,10 @@ void start_tty(struct tty_struct *tty)
EXPORT_SYMBOL(start_tty);
+/* We limit tty time update visibility to every 8 seconds or so. */
static void tty_update_time(struct timespec *time)
{
- unsigned long sec = get_seconds();
- sec -= sec % 60;
+ unsigned long sec = get_seconds() & ~7;
if ((long)(sec - time->tv_sec) > 0)
time->tv_sec = sec;
}