diff options
Diffstat (limited to 'tty-dont-allow-reopen-when-ldisc-is-changing.patch')
| -rw-r--r-- | tty-dont-allow-reopen-when-ldisc-is-changing.patch | 84 |
1 files changed, 0 insertions, 84 deletions
diff --git a/tty-dont-allow-reopen-when-ldisc-is-changing.patch b/tty-dont-allow-reopen-when-ldisc-is-changing.patch deleted file mode 100644 index 02d6746fc..000000000 --- a/tty-dont-allow-reopen-when-ldisc-is-changing.patch +++ /dev/null @@ -1,84 +0,0 @@ -From jirislaby@gmail.com Thu Nov 25 12:16:42 2010 -From: Jiri Slaby <jslaby@suse.cz> -Subject: [PATCH 1/1] TTY: don't allow reopen when ldisc is changing -Date: Thu, 25 Nov 2010 18:16:23 +0100 - -There are many WARNINGs like the following reported nowadays: -WARNING: at drivers/tty/tty_io.c:1331 tty_open+0x2a2/0x49a() -Hardware name: Latitude E6500 -Modules linked in: -Pid: 1207, comm: plymouthd Not tainted 2.6.37-rc3-mmotm1123 #3 -Call Trace: - [<ffffffff8103b189>] warn_slowpath_common+0x80/0x98 - [<ffffffff8103b1b6>] warn_slowpath_null+0x15/0x17 - [<ffffffff8128a3ab>] tty_open+0x2a2/0x49a - [<ffffffff810fd53f>] chrdev_open+0x11d/0x146 -... - -This means tty_reopen is called without TTY_LDISC set. For further -considerations, note tty_lock is held in tty_open. TTY_LDISC is cleared in: -1) __tty_hangup from tty_ldisc_hangup to tty_ldisc_enable. During this -section tty_lock is held. - -2) tty_release via tty_ldisc_release till the end of tty existence. If -tty->count <= 1, tty_lock is taken, TTY_CLOSING bit set and then -tty_ldisc_release called. tty_reopen checks TTY_CLOSING before checking -TTY_LDISC. - -3) tty_set_ldisc from tty_ldisc_halt to tty_ldisc_enable. We: - * take tty_lock, set TTY_LDISC_CHANGING, put tty_lock - * call tty_ldisc_halt (clear TTY_LDISC), tty_lock is _not_ held - * do some other work - * take tty_lock, call tty_ldisc_enable (set TTY_LDISC), put - tty_lock - -So the only option I see is 3). The solution is to check -TTY_LDISC_CHANGING along with TTY_CLOSING in tty_reopen. - -Nicely reproducible with two processes: -while (1) { - fd = open("/dev/ttyS1", O_RDWR); - if (fd < 0) { - warn("open"); - continue; - } - close(fd); -} --------- -while (1) { - fd = open("/dev/ttyS1", O_RDWR); - ld1 = 0; ld2 = 2; - while (1) { - ioctl(fd, TIOCSETD, &ld1); - ioctl(fd, TIOCSETD, &ld2); - } - close(fd); -} - -Signed-off-by: Jiri Slaby <jslaby@suse.cz> -Reported-by: <Valdis.Kletnieks@vt.edu> -Cc: Kyle McMartin <kyle@mcmartin.ca> -Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> ---- - drivers/tty/tty_io.c | 3 ++- - 1 files changed, 2 insertions(+), 1 deletions(-) - -diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c -index c05c5af..878f6d6 100644 ---- a/drivers/tty/tty_io.c -+++ b/drivers/tty/tty_io.c -@@ -1310,7 +1310,8 @@ static int tty_reopen(struct tty_struct *tty) - { - struct tty_driver *driver = tty->driver; - -- if (test_bit(TTY_CLOSING, &tty->flags)) -+ if (test_bit(TTY_CLOSING, &tty->flags) || -+ test_bit(TTY_LDISC_CHANGING, &tty->flags)) - return -EIO; - - if (driver->type == TTY_DRIVER_TYPE_PTY && --- -1.7.3.1 - - - |