Prevent buffer work scheduling when called from n_tty_close(). Since
the ldisc has been halted and the tty soon-to-be-destructed, pending
work would be accessing an invalid tty and ldisc state. Fixes this:
[ 38.051111] ------------[ cut here ]------------
[ 38.052113] WARNING: at /home/peter/src/kernels/next/drivers/tty/n_tty.c:160 n_tty_set_room.part.6+0x8b/0xa0()
[ 38.053916] Hardware name: Bochs
[ 38.054819] Modules linked in: netconsole configfs bnep rfcomm bluetooth parport_pc ppdev snd_hda_intel snd_hda_codec
snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq psmouse snd_timer serio_raw mac_hid snd_seq_device
snd microcode lp parport virtio_balloon soundcore i2c_piix4 snd_page_alloc floppy 8139too 8139cp
[ 38.059704] Pid: 1564, comm: pty_kill Tainted: G W 3.7.0-next-20121130+ttydebug-xeon #20121130+ttydebug
[ 38.061578] Call Trace:
[ 38.062491] [<ffffffff81058b4f>] warn_slowpath_common+0x7f/0xc0
[ 38.063448] [<ffffffff81058baa>] warn_slowpath_null+0x1a/0x20
[ 38.064439] [<ffffffff8142dc2b>] n_tty_set_room.part.6+0x8b/0xa0
[ 38.065381] [<ffffffff8142dc82>] n_tty_set_room+0x42/0x80
[ 38.066323] [<ffffffff8142e6f2>] reset_buffer_flags+0x102/0x160
[ 38.077508] [<ffffffff8142e76d>] n_tty_flush_buffer+0x1d/0x90
[ 38.078782] [<ffffffff81046569>] ? default_spin_lock_flags+0x9/0x10
[ 38.079734] [<ffffffff8142e804>] n_tty_close+0x24/0x60
[ 38.080730] [<ffffffff81431b61>] tty_ldisc_close.isra.2+0x41/0x60
[ 38.081680] [<ffffffff81431bbb>] tty_ldisc_kill+0x3b/0x80
[ 38.082618] [<ffffffff81432a07>] tty_ldisc_release+0x77/0xe0
[ 38.083549] [<ffffffff8142b781>] tty_release+0x451/0x4d0
[ 38.084525] [<ffffffff811950be>] __fput+0xae/0x230
[ 38.085472] [<ffffffff8119524e>] ____fput+0xe/0x10
[ 38.086401] [<ffffffff8107aa88>] task_work_run+0xc8/0xf0
[ 38.087334] [<ffffffff8105ea56>] do_exit+0x196/0x4b0
[ 38.088304] [<ffffffff8106c77b>] ? __dequeue_signal+0x6b/0xb0
[ 38.089240] [<ffffffff8105ef34>] do_group_exit+0x44/0xa0
[ 38.090182] [<ffffffff8106f43d>] get_signal_to_deliver+0x20d/0x4e0
[ 38.091125] [<ffffffff81016979>] do_signal+0x29/0x130
[ 38.092096] [<ffffffff81431a9e>] ? tty_ldisc_deref+0xe/0x10
[ 38.093030] [<ffffffff8142a317>] ? tty_write+0xb7/0xf0
[ 38.093976] [<ffffffff81193f53>] ? vfs_write+0xb3/0x180
[ 38.094904] [<ffffffff81016b20>] do_notify_resume+0x80/0xc0
[ 38.095830] [<ffffffff81700492>] int_signal+0x12/0x17
[ 38.096788] ---[ end trace 5f6f7a9651cd999b ]---
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 3f704a9..574d099 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -149,7 +149,7 @@ static void n_tty_set_room(struct tty_struct *tty)
tty->receive_room = left;
/* Did this open up the receive buffer? We may need to flip */
- if (left && !old_left) {
+ if (left && !old_left && !test_bit(TTY_CLOSING, &tty->flags)) {
WARN_RATELIMIT(tty->port->itty == NULL,
"scheduling with invalid itty\n");
/* see if ldisc has been killed - if so, this means that
--
1.8.0
--
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