From b66f4fa509153ca9d313075806d5c6425dfa43c5 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Mon, 11 Mar 2013 16:44:32 -0400 Subject: [PATCH] n_tty: Fully initialize ldisc before restarting buffer work Buffer work may already be pending when the n_tty ldisc is re-opened, eg., when setting the ldisc (via TIOCSETD ioctl) and when hanging up the tty. Since n_tty_set_room() may restart buffer work, first ensure the ldisc is completely initialized. Factor n_tty_set_room() out of reset_buffer_flags() (only 2 callers) and reorganize n_tty_open() to set termios last; buffer work will be restarted there if necessary, after the char_map is properly initialized. Fixes this WARNING: [ 549.561769] ------------[ cut here ]------------ [ 549.598755] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room+0xff/0x130() [ 549.604058] scheduling buffer work for halted ldisc [ 549.607741] Pid: 9417, comm: trinity-child28 Tainted: G D W 3.7.0-next-20121217-sasha-00023-g8689ef9 #219 [ 549.652580] Call Trace: [ 549.662754] [] ? n_tty_set_room+0xff/0x130 [ 549.665458] [] warn_slowpath_common+0x87/0xb0 [ 549.668257] [] warn_slowpath_fmt+0x41/0x50 [ 549.671007] [] n_tty_set_room+0xff/0x130 [ 549.673268] [] reset_buffer_flags+0x137/0x150 [ 549.675607] [] n_tty_open+0x131/0x1c0 [ 549.677699] [] tty_ldisc_open.isra.5+0x54/0x70 [ 549.680147] [] tty_ldisc_hangup+0x11f/0x1e0 [ 549.682409] [] __tty_hangup+0x137/0x440 [ 549.684634] [] tty_vhangup+0x9/0x10 [ 549.686443] [] pty_close+0x14c/0x160 [ 549.688446] [] tty_release+0xd5/0x490 [ 549.690460] [] __fput+0x122/0x250 [ 549.692577] [] ____fput+0x9/0x10 [ 549.694534] [] task_work_run+0xb2/0xf0 [ 549.696349] [] do_exit+0x36d/0x580 [ 549.698286] [] ? syscall_trace_enter+0x24/0x2e0 [ 549.702729] [] do_group_exit+0x8a/0xc0 [ 549.706775] [] sys_exit_group+0x12/0x20 [ 549.711088] [] tracesys+0xe1/0xe6 [ 549.728001] ---[ end trace 73eb41728f11f87e ]--- Reported-by: Sasha Levin Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 0d3f715de7d2..d655416087b7 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -204,9 +204,8 @@ static void put_tty_queue(unsigned char c, struct n_tty_data *ldata) * Locking: tty_read_lock for read fields. */ -static void reset_buffer_flags(struct tty_struct *tty) +static void reset_buffer_flags(struct n_tty_data *ldata) { - struct n_tty_data *ldata = tty->disc_data; unsigned long flags; raw_spin_lock_irqsave(&ldata->read_lock, flags); @@ -219,7 +218,6 @@ static void reset_buffer_flags(struct tty_struct *tty) ldata->canon_head = ldata->canon_data = ldata->erasing = 0; bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); - n_tty_set_room(tty); } static void n_tty_packet_mode_flush(struct tty_struct *tty) @@ -247,7 +245,8 @@ static void n_tty_packet_mode_flush(struct tty_struct *tty) static void n_tty_flush_buffer(struct tty_struct *tty) { - reset_buffer_flags(tty); + reset_buffer_flags(tty->disc_data); + n_tty_set_room(tty); if (tty->link) n_tty_packet_mode_flush(tty); @@ -1633,14 +1632,14 @@ static int n_tty_open(struct tty_struct *tty) goto err_free_bufs; tty->disc_data = ldata; - /* indicate buffer work may resume */ - clear_bit(TTY_LDISC_HALTED, &tty->flags); - reset_buffer_flags(tty); - tty_unthrottle(tty); + reset_buffer_flags(tty->disc_data); ldata->column = 0; - n_tty_set_termios(tty, NULL); tty->minimum_to_wake = 1; tty->closing = 0; + /* indicate buffer work may resume */ + clear_bit(TTY_LDISC_HALTED, &tty->flags); + n_tty_set_termios(tty, NULL); + tty_unthrottle(tty); return 0; err_free_bufs: -- 2.20.1